[core] make forcing cache/network only more explicit

Previously, we used the existence of a `prior*` field in the Resource object as an indication for whether we should consult the cache or not. However, this is prone to error, since a failed cache lookup won't set any prior fields. Therefore, we manually set `priorExpires` to 0. This in turn triggered another bug where generated wrong expiration timestamps when the server response we got was expired (or expired between sending and receiving).

This commit changes the flags so that we can now explicitly request CacheOnly/NetworkOnly (or All) loading methods, rather than the implicit Optional/Required naming scheme.

3 files changed, 129 insertions, 129 deletions

diff --git a/test/algorithm/mock.hpp b/test/algorithm/mock.hpp
index d87f55343b..b8eb020105 100644
--- a/test/algorithm/mock.hpp
+++ b/test/algorithm/mock.hpp
@@ -26,7 +26,7 @@ struct MockBucket {};
 struct MockTileData {
     MockTileData(const mbgl::OverscaledTileID& tileID_) : tileID(tileID_) {}
 
-    bool hasTriedOptional() const {
+    bool hasTriedCache() const {
         return triedOptional;
     }
 
diff --git a/test/algorithm/update_renderables.test.cpp b/test/algorithm/update_renderables.test.cpp
index 2d37992579..7d6a0fcb13 100644
--- a/test/algorithm/update_renderables.test.cpp
+++ b/test/algorithm/update_renderables.test.cpp
@@ -45,7 +45,7 @@ std::ostream& operator<<(std::ostream& os, const CreateTileDataAction& action) {
 
 struct RetainTileDataAction {
     const OverscaledTileID tileID;
-    const Resource::Necessity necessity;
+    const TileNecessity necessity;
 
     bool operator==(const RetainTileDataAction& rhs) const {
         return tileID == rhs.tileID && necessity == rhs.necessity;
@@ -56,7 +56,7 @@ std::ostream& operator<<(std::ostream& os, const RetainTileDataAction& action) {
     return os << "RetainTileDataAction{ { " << int(action.tileID.overscaledZ) << ", " << int(action.tileID.wrap) << ", { "
               << int(action.tileID.canonical.z) << ", " << action.tileID.canonical.x << ", "
               << action.tileID.canonical.y << " } }, "
-              << (action.necessity == Resource::Necessity::Required ? "Required" : "Optional") << " }\n";
+              << (action.necessity == TileNecessity::Required ? "Required" : "Optional") << " }\n";
 }
 
 struct RenderTileAction {
@@ -102,7 +102,7 @@ auto createTileDataFn(ActionLog& log, T& dataTiles) {
 
 template <typename = int>
 auto retainTileDataFn(ActionLog& log) {
-    return [&](auto& tileData, Resource::Necessity necessity) {
+    return [&](auto& tileData, TileNecessity necessity) {
         log.emplace_back(RetainTileDataAction{ tileData.tileID, necessity });
     };
 }
@@ -132,7 +132,7 @@ TEST(UpdateRenderables, SingleTile) {
                                  source.idealTiles, source.zoomRange, 1);
     EXPECT_EQ(ActionLog({
                   GetTileDataAction{ { 1, 0, { 1, 1, 1 } }, Found },       // found ideal tile
-                  RetainTileDataAction{ { 1, 0, { 1, 1, 1 } }, Resource::Necessity::Required }, //
+                  RetainTileDataAction{ { 1, 0, { 1, 1, 1 } }, TileNecessity::Required }, //
                   RenderTileAction{ { 1, 1, 1 }, *tile_1_1_1_1 },       // render ideal tile
               }),
               log);
@@ -143,7 +143,7 @@ TEST(UpdateRenderables, SingleTile) {
                                  source.idealTiles, source.zoomRange, 1);
     EXPECT_EQ(ActionLog({
                   GetTileDataAction{ { 1, 0, { 1, 1, 1 } }, Found },       // found ideal tile
-                  RetainTileDataAction{ { 1, 0, { 1, 1, 1 } }, Resource::Necessity::Required }, //
+                  RetainTileDataAction{ { 1, 0, { 1, 1, 1 } }, TileNecessity::Required }, //
                   RenderTileAction{ { 1, 1, 1 }, *tile_1_1_1_1 },       // render ideal tile
               }),
               log);
@@ -156,7 +156,7 @@ TEST(UpdateRenderables, SingleTile) {
     EXPECT_EQ(ActionLog({
                   GetTileDataAction{ { 1, 0, { 1, 0, 1 } }, NotFound },    // missing ideal tile
                   CreateTileDataAction{ { 1, 0, { 1, 0, 1 } } },           // create ideal tile
-                  RetainTileDataAction{ { 1, 0, { 1, 0, 1 } }, Resource::Necessity::Required }, //
+                  RetainTileDataAction{ { 1, 0, { 1, 0, 1 } }, TileNecessity::Required }, //
                   GetTileDataAction{ { 2, 0, { 2, 0, 2 } }, NotFound },    // four child tiles
                   GetTileDataAction{ { 2, 0, { 2, 0, 3 } }, NotFound },    // ...
                   GetTileDataAction{ { 2, 0, { 2, 1, 2 } }, NotFound },    // ...
@@ -164,7 +164,7 @@ TEST(UpdateRenderables, SingleTile) {
                   GetTileDataAction{ { 0, 0, { 0, 0, 0 } }, NotFound },    // parent tile
 
                   GetTileDataAction{ { 1, 0, { 1, 1, 1 } }, Found },       // found ideal tile
-                  RetainTileDataAction{ { 1, 0, { 1, 1, 1 } }, Resource::Necessity::Required }, //
+                  RetainTileDataAction{ { 1, 0, { 1, 1, 1 } }, TileNecessity::Required }, //
                   RenderTileAction{ { 1, 1, 1 }, *tile_1_1_1_1 },       // render found tile
               }),
               log);
@@ -176,17 +176,17 @@ TEST(UpdateRenderables, SingleTile) {
                                  source.idealTiles, source.zoomRange, 1);
     EXPECT_EQ(ActionLog({
                   GetTileDataAction{ { 1, 0, { 1, 0, 1 } }, Found },       // missing ideal tile
-                  RetainTileDataAction{ { 1, 0, { 1, 0, 1 } }, Resource::Necessity::Required }, //
+                  RetainTileDataAction{ { 1, 0, { 1, 0, 1 } }, TileNecessity::Required }, //
                   GetTileDataAction{ { 2, 0, { 2, 0, 2 } }, NotFound },    // four child tiles
                   GetTileDataAction{ { 2, 0, { 2, 0, 3 } }, NotFound },    // ...
                   GetTileDataAction{ { 2, 0, { 2, 1, 2 } }, NotFound },    // ...
                   GetTileDataAction{ { 2, 0, { 2, 1, 3 } }, NotFound },    // ...
                   GetTileDataAction{ { 0, 0, { 0, 0, 0 } }, NotFound },    // parent tile
                   CreateTileDataAction{ { 0, 0, { 0, 0, 0 } } },           // load parent tile
-                  RetainTileDataAction{ { 0, 0, { 0, 0, 0 } }, Resource::Necessity::Optional }, //
+                  RetainTileDataAction{ { 0, 0, { 0, 0, 0 } }, TileNecessity::Optional }, //
 
                   GetTileDataAction{ { 1, 0, { 1, 1, 1 } }, Found },       // found ideal tile
-                  RetainTileDataAction{ { 1, 0, { 1, 1, 1 } }, Resource::Necessity::Required }, //
+                  RetainTileDataAction{ { 1, 0, { 1, 1, 1 } }, TileNecessity::Required }, //
                   RenderTileAction{ { 1, 1, 1 }, *tile_1_1_1_1 },       // render found tile
               }),
               log);
@@ -199,11 +199,11 @@ TEST(UpdateRenderables, SingleTile) {
                                  source.idealTiles, source.zoomRange, 1);
     EXPECT_EQ(ActionLog({
                   GetTileDataAction{ { 1, 0, { 1, 0, 1 } }, Found },       // newly added tile
-                  RetainTileDataAction{ { 1, 0, { 1, 0, 1 } }, Resource::Necessity::Required }, //
+                  RetainTileDataAction{ { 1, 0, { 1, 0, 1 } }, TileNecessity::Required }, //
                   RenderTileAction{ { 1, 0, 1 }, *tile_1_1_0_1 },       // render ideal tile
 
                   GetTileDataAction{ { 1, 0, { 1, 1, 1 } }, Found },       // ideal tile
-                  RetainTileDataAction{ { 1, 0, { 1, 1, 1 } }, Resource::Necessity::Required }, //
+                  RetainTileDataAction{ { 1, 0, { 1, 1, 1 } }, TileNecessity::Required }, //
                   RenderTileAction{ { 1, 1, 1 }, *tile_1_1_1_1 },       // render found tile
               }),
               log);
@@ -218,21 +218,21 @@ TEST(UpdateRenderables, SingleTile) {
                                  source.idealTiles, source.zoomRange, 1);
     EXPECT_EQ(ActionLog({
                   GetTileDataAction{ { 1, 0, { 1, 0, 0 } }, Found },       // found tile, not ready
-                  RetainTileDataAction{ { 1, 0, { 1, 0, 0 } }, Resource::Necessity::Required }, //
+                  RetainTileDataAction{ { 1, 0, { 1, 0, 0 } }, TileNecessity::Required }, //
                   GetTileDataAction{ { 2, 0, { 2, 0, 0 } }, NotFound },    // four child tiles
                   GetTileDataAction{ { 2, 0, { 2, 0, 1 } }, NotFound },    // ...
                   GetTileDataAction{ { 2, 0, { 2, 1, 0 } }, NotFound },    // ...
                   GetTileDataAction{ { 2, 0, { 2, 1, 1 } }, NotFound },    // ...
                   GetTileDataAction{ { 0, 0, { 0, 0, 0 } }, Found },       // parent tile
-                  RetainTileDataAction{ { 0, 0, { 0, 0, 0 } }, Resource::Necessity::Optional }, //
+                  RetainTileDataAction{ { 0, 0, { 0, 0, 0 } }, TileNecessity::Optional }, //
                   // optional parent tile was already created before, but is not renderable
 
                   GetTileDataAction{ { 1, 0, { 1, 0, 1 } }, Found },       // ideal tile
-                  RetainTileDataAction{ { 1, 0, { 1, 0, 1 } }, Resource::Necessity::Required }, //
+                  RetainTileDataAction{ { 1, 0, { 1, 0, 1 } }, TileNecessity::Required }, //
                   RenderTileAction{ { 1, 0, 1 }, *tile_1_1_0_1 },       // render ideal tile
 
                   GetTileDataAction{ { 1, 0, { 1, 1, 1 } }, Found },       // ideal tile
-                  RetainTileDataAction{ { 1, 0, { 1, 1, 1 } }, Resource::Necessity::Required }, //
+                  RetainTileDataAction{ { 1, 0, { 1, 1, 1 } }, TileNecessity::Required }, //
                   RenderTileAction{ { 1, 1, 1 }, *tile_1_1_1_1 },       // render ideal tile
               }),
               log);
@@ -244,15 +244,15 @@ TEST(UpdateRenderables, SingleTile) {
                                  source.idealTiles, source.zoomRange, 1);
     EXPECT_EQ(ActionLog({
                   GetTileDataAction{ { 1, 0, { 1, 0, 0 } }, Found },       // found tile, now ready
-                  RetainTileDataAction{ { 1, 0, { 1, 0, 0 } }, Resource::Necessity::Required }, //
+                  RetainTileDataAction{ { 1, 0, { 1, 0, 0 } }, TileNecessity::Required }, //
                   RenderTileAction{ { 1, 0, 0 }, *tile_1_1_0_0 },       //
 
                   GetTileDataAction{ { 1, 0, { 1, 0, 1 } }, Found },       // ideal tile
-                  RetainTileDataAction{ { 1, 0, { 1, 0, 1 } }, Resource::Necessity::Required }, //
+                  RetainTileDataAction{ { 1, 0, { 1, 0, 1 } }, TileNecessity::Required }, //
                   RenderTileAction{ { 1, 0, 1 }, *tile_1_1_0_1 },       //
 
                   GetTileDataAction{ { 1, 0, { 1, 1, 1 } }, Found },       // ideal tile
-                  RetainTileDataAction{ { 1, 0, { 1, 1, 1 } }, Resource::Necessity::Required }, //
+                  RetainTileDataAction{ { 1, 0, { 1, 1, 1 } }, TileNecessity::Required }, //
                   RenderTileAction{ { 1, 1, 1 }, *tile_1_1_1_1 },       //
               }),
               log);
@@ -278,24 +278,24 @@ TEST(UpdateRenderables, UseParentTile) {
     EXPECT_EQ(ActionLog({
                   GetTileDataAction{ { 1, 0, { 1, 0, 1 } }, NotFound },    // missing ideal tile
                   CreateTileDataAction{ { 1, 0, { 1, 0, 1 } } },           //
-                  RetainTileDataAction{ { 1, 0, { 1, 0, 1 } }, Resource::Necessity::Required }, //
+                  RetainTileDataAction{ { 1, 0, { 1, 0, 1 } }, TileNecessity::Required }, //
                   GetTileDataAction{ { 2, 0, { 2, 0, 2 } }, NotFound },    // child tile
                   GetTileDataAction{ { 2, 0, { 2, 0, 3 } }, NotFound },    // ...
                   GetTileDataAction{ { 2, 0, { 2, 1, 2 } }, NotFound },    // ...
                   GetTileDataAction{ { 2, 0, { 2, 1, 3 } }, NotFound },    // ...
                   GetTileDataAction{ { 0, 0, { 0, 0, 0 } }, Found },       // parent found!
-                  RetainTileDataAction{ { 0, 0, { 0, 0, 0 } }, Resource::Necessity::Optional }, //
+                  RetainTileDataAction{ { 0, 0, { 0, 0, 0 } }, TileNecessity::Optional }, //
                   RenderTileAction{ { 0, 0, 0 }, *tile_0_0_0_0 },       // render parent
                   GetTileDataAction{ { 1, 0, { 1, 1, 0 } }, NotFound },    // missing ideal tile
                   CreateTileDataAction{ { 1, 0, { 1, 1, 0 } } },           //
-                  RetainTileDataAction{ { 1, 0, { 1, 1, 0 } }, Resource::Necessity::Required }, //
+                  RetainTileDataAction{ { 1, 0, { 1, 1, 0 } }, TileNecessity::Required }, //
                   GetTileDataAction{ { 2, 0, { 2, 2, 0 } }, NotFound },    // child tile
                   GetTileDataAction{ { 2, 0, { 2, 2, 1 } }, NotFound },    // ...
                   GetTileDataAction{ { 2, 0, { 2, 3, 0 } }, NotFound },    // ...
                   GetTileDataAction{ { 2, 0, { 2, 3, 1 } }, NotFound },    // ...
                   GetTileDataAction{ { 1, 0, { 1, 1, 1 } }, NotFound },    // missing tile
                   CreateTileDataAction{ { 1, 0, { 1, 1, 1 } } },           //
-                  RetainTileDataAction{ { 1, 0, { 1, 1, 1 } }, Resource::Necessity::Required }, //
+                  RetainTileDataAction{ { 1, 0, { 1, 1, 1 } }, TileNecessity::Required }, //
                   GetTileDataAction{ { 2, 0, { 2, 2, 2 } }, NotFound },    // child tile
                   GetTileDataAction{ { 2, 0, { 2, 2, 3 } }, NotFound },    // ...
                   GetTileDataAction{ { 2, 0, { 2, 3, 2 } }, NotFound },    // ...
@@ -321,7 +321,7 @@ TEST(UpdateRenderables, DontUseWrongParentTile) {
     EXPECT_EQ(ActionLog({
                   GetTileDataAction{ { 2, 0, { 2, 0, 0 } }, NotFound },    // missing ideal tile
                   CreateTileDataAction{ { 2, 0, { 2, 0, 0 } } },           //
-                  RetainTileDataAction{ { 2, 0, { 2, 0, 0 } }, Resource::Necessity::Required }, //
+                  RetainTileDataAction{ { 2, 0, { 2, 0, 0 } }, TileNecessity::Required }, //
                   GetTileDataAction{ { 3, 0, { 3, 0, 0 } }, NotFound },    // child tile
                   GetTileDataAction{ { 3, 0, { 3, 0, 1 } }, NotFound },    // ...
                   GetTileDataAction{ { 3, 0, { 3, 1, 0 } }, NotFound },    // ...
@@ -338,14 +338,14 @@ TEST(UpdateRenderables, DontUseWrongParentTile) {
                                  source.idealTiles, source.zoomRange, 2);
     EXPECT_EQ(ActionLog({
                   GetTileDataAction{ { 2, 0, { 2, 0, 0 } }, Found },       // non-ready ideal tile
-                  RetainTileDataAction{ { 2, 0, { 2, 0, 0 } }, Resource::Necessity::Required }, //
+                  RetainTileDataAction{ { 2, 0, { 2, 0, 0 } }, TileNecessity::Required }, //
                   GetTileDataAction{ { 3, 0, { 3, 0, 0 } }, NotFound },    // child tile
                   GetTileDataAction{ { 3, 0, { 3, 0, 1 } }, NotFound },    // ...
                   GetTileDataAction{ { 3, 0, { 3, 1, 0 } }, NotFound },    // ...
                   GetTileDataAction{ { 3, 0, { 3, 1, 1 } }, NotFound },    // ...
                   GetTileDataAction{ { 1, 0, { 1, 0, 0 } }, NotFound },    // parent tile, missing
                   CreateTileDataAction{ { 1, 0, { 1, 0, 0 } } },           // find optional parent
-                  RetainTileDataAction{ { 1, 0, { 1, 0, 0 } }, Resource::Necessity::Optional }, //
+                  RetainTileDataAction{ { 1, 0, { 1, 0, 0 } }, TileNecessity::Optional }, //
                   GetTileDataAction{ { 0, 0, { 0, 0, 0 } }, NotFound },    // parent tile, missing
               }),
               log);
@@ -357,25 +357,25 @@ TEST(UpdateRenderables, DontUseWrongParentTile) {
                                  source.idealTiles, source.zoomRange, 2);
     EXPECT_EQ(ActionLog({
                   GetTileDataAction{ { 2, 0, { 2, 0, 0 } }, Found },       // non-ready ideal tile
-                  RetainTileDataAction{ { 2, 0, { 2, 0, 0 } }, Resource::Necessity::Required }, //
+                  RetainTileDataAction{ { 2, 0, { 2, 0, 0 } }, TileNecessity::Required }, //
                   // this tile was added by the previous invocation of updateRenderables
                   GetTileDataAction{ { 3, 0, { 3, 0, 0 } }, NotFound },    // child tile
                   GetTileDataAction{ { 3, 0, { 3, 0, 1 } }, NotFound },    // ...
                   GetTileDataAction{ { 3, 0, { 3, 1, 0 } }, NotFound },    // ...
                   GetTileDataAction{ { 3, 0, { 3, 1, 1 } }, NotFound },    // ...
                   GetTileDataAction{ { 1, 0, { 1, 0, 0 } }, Found },       // parent tile not ready
-                  RetainTileDataAction{ { 1, 0, { 1, 0, 0 } }, Resource::Necessity::Optional }, //
+                  RetainTileDataAction{ { 1, 0, { 1, 0, 0 } }, TileNecessity::Optional }, //
                   GetTileDataAction{ { 0, 0, { 0, 0, 0 } }, NotFound },    // missing parent tile
 
                   GetTileDataAction{ { 2, 0, { 2, 2, 0 } }, NotFound },    // missing ideal tile
                   CreateTileDataAction{ { 2, 0, { 2, 2, 0 } } },           //
-                  RetainTileDataAction{ { 2, 0, { 2, 2, 0 } }, Resource::Necessity::Required }, //
+                  RetainTileDataAction{ { 2, 0, { 2, 2, 0 } }, TileNecessity::Required }, //
                   GetTileDataAction{ { 3, 0, { 3, 4, 0 } }, NotFound },    // child tile
                   GetTileDataAction{ { 3, 0, { 3, 4, 1 } }, NotFound },    // ...
                   GetTileDataAction{ { 3, 0, { 3, 5, 0 } }, NotFound },    // ...
                   GetTileDataAction{ { 3, 0, { 3, 5, 1 } }, NotFound },    // ...
                   GetTileDataAction{ { 1, 0, { 1, 1, 0 } }, Found },       // found parent tile
-                  RetainTileDataAction{ { 1, 0, { 1, 1, 0 } }, Resource::Necessity::Optional }, //
+                  RetainTileDataAction{ { 1, 0, { 1, 1, 0 } }, TileNecessity::Optional }, //
                   RenderTileAction{ { 1, 1, 0 }, *tile_1_1_1_0 },       // render parent tile
               }),
               log);
@@ -402,13 +402,13 @@ TEST(UpdateRenderables, UseParentTileWhenChildNotReady) {
                                  source.idealTiles, source.zoomRange, 1);
     EXPECT_EQ(ActionLog({
                   GetTileDataAction{ { 1, 0, { 1, 0, 1 } }, Found },       // found, but not ready
-                  RetainTileDataAction{ { 1, 0, { 1, 0, 1 } }, Resource::Necessity::Required }, //
+                  RetainTileDataAction{ { 1, 0, { 1, 0, 1 } }, TileNecessity::Required }, //
                   GetTileDataAction{ { 2, 0, { 2, 0, 2 } }, NotFound },    // child tile
                   GetTileDataAction{ { 2, 0, { 2, 0, 3 } }, NotFound },    // ...
                   GetTileDataAction{ { 2, 0, { 2, 1, 2 } }, NotFound },    // ...
                   GetTileDataAction{ { 2, 0, { 2, 1, 3 } }, NotFound },    // ...
                   GetTileDataAction{ { 0, 0, { 0, 0, 0 } }, Found },       // parent tile, ready
-                  RetainTileDataAction{ { 0, 0, { 0, 0, 0 } }, Resource::Necessity::Optional }, //
+                  RetainTileDataAction{ { 0, 0, { 0, 0, 0 } }, TileNecessity::Optional }, //
                   RenderTileAction{ { 0, 0, 0 }, *tile_0_0_0_0 },       // render parent tile
               }),
               log);
@@ -420,7 +420,7 @@ TEST(UpdateRenderables, UseParentTileWhenChildNotReady) {
                                  source.idealTiles, source.zoomRange, 1);
     EXPECT_EQ(ActionLog({
                   GetTileDataAction{ { 1, 0, { 1, 0, 1 } }, Found },       // found and ready
-                  RetainTileDataAction{ { 1, 0, { 1, 0, 1 } }, Resource::Necessity::Required }, //
+                  RetainTileDataAction{ { 1, 0, { 1, 0, 1 } }, TileNecessity::Required }, //
                   RenderTileAction{ { 1, 0, 1 }, *tile_1_1_0_1 },       // render ideal tile
               }),
               log);
@@ -448,17 +448,17 @@ TEST(UpdateRenderables, UseOverlappingParentTile) {
     EXPECT_EQ(ActionLog({
                   GetTileDataAction{ { 1, 0, { 1, 0, 0 } }, NotFound },    // ideal tile not found
                   CreateTileDataAction{ { 1, 0, { 1, 0, 0 } } },           //
-                  RetainTileDataAction{ { 1, 0, { 1, 0, 0 } }, Resource::Necessity::Required }, //
+                  RetainTileDataAction{ { 1, 0, { 1, 0, 0 } }, TileNecessity::Required }, //
                   GetTileDataAction{ { 2, 0, { 2, 0, 0 } }, NotFound },    // child tile
                   GetTileDataAction{ { 2, 0, { 2, 0, 1 } }, NotFound },    // ...
                   GetTileDataAction{ { 2, 0, { 2, 1, 0 } }, NotFound },    // ...
                   GetTileDataAction{ { 2, 0, { 2, 1, 1 } }, NotFound },    // ...
                   GetTileDataAction{ { 0, 0, { 0, 0, 0 } }, Found },       // parent tile found
-                  RetainTileDataAction{ { 0, 0, { 0, 0, 0 } }, Resource::Necessity::Optional }, //
+                  RetainTileDataAction{ { 0, 0, { 0, 0, 0 } }, TileNecessity::Optional }, //
                   RenderTileAction{ { 0, 0, 0 }, *tile_0_0_0_0 },       //
 
                   GetTileDataAction{ { 1, 0, { 1, 0, 1 } }, Found },       // ideal tile found
-                  RetainTileDataAction{ { 1, 0, { 1, 0, 1 } }, Resource::Necessity::Required }, //
+                  RetainTileDataAction{ { 1, 0, { 1, 0, 1 } }, TileNecessity::Required }, //
                   RenderTileAction{ { 1, 0, 1 }, *tile_1_1_0_1 },       //
               }),
               log);
@@ -484,13 +484,13 @@ TEST(UpdateRenderables, UseChildTiles) {
     EXPECT_EQ(ActionLog({
                   GetTileDataAction{ { 0, 0, { 0, 0, 0 } }, NotFound },    // ideal tile, missing
                   CreateTileDataAction{ { 0, 0, { 0, 0, 0 } } },           //
-                  RetainTileDataAction{ { 0, 0, { 0, 0, 0 } }, Resource::Necessity::Required }, //
+                  RetainTileDataAction{ { 0, 0, { 0, 0, 0 } }, TileNecessity::Required }, //
                   GetTileDataAction{ { 1, 0, { 1, 0, 0 } }, Found },       // child tile found
-                  RetainTileDataAction{ { 1, 0, { 1, 0, 0 } }, Resource::Necessity::Optional }, //
+                  RetainTileDataAction{ { 1, 0, { 1, 0, 0 } }, TileNecessity::Optional }, //
                   RenderTileAction{ { 1, 0, 0 }, *tile_1_1_0_0 },       // render child tile
                   GetTileDataAction{ { 1, 0, { 1, 0, 1 } }, NotFound },    // child tile not found
                   GetTileDataAction{ { 1, 0, { 1, 1, 0 } }, Found },       // child tile found
-                  RetainTileDataAction{ { 1, 0, { 1, 1, 0 } }, Resource::Necessity::Optional }, //
+                  RetainTileDataAction{ { 1, 0, { 1, 1, 0 } }, TileNecessity::Optional }, //
                   RenderTileAction{ { 1, 1, 0 }, *tile_1_1_1_0 },       // render child tile
                   GetTileDataAction{ { 1, 0, { 1, 1, 1 } }, NotFound },    // child tile not found
                   // no parent tile of 0 to consider
@@ -518,15 +518,15 @@ TEST(UpdateRenderables, PreferChildTiles) {
     EXPECT_EQ(ActionLog({
                   GetTileDataAction{ { 1, 0, { 1, 0, 0 } }, NotFound },    // ideal tile, not found
                   CreateTileDataAction{ { 1, 0, { 1, 0, 0 } } },           //
-                  RetainTileDataAction{ { 1, 0, { 1, 0, 0 } }, Resource::Necessity::Required }, //
+                  RetainTileDataAction{ { 1, 0, { 1, 0, 0 } }, TileNecessity::Required }, //
                   GetTileDataAction{ { 2, 0, { 2, 0, 0 } }, Found },       // child tile, found
-                  RetainTileDataAction{ { 2, 0, { 2, 0, 0 } }, Resource::Necessity::Optional }, //
+                  RetainTileDataAction{ { 2, 0, { 2, 0, 0 } }, TileNecessity::Optional }, //
                   RenderTileAction{ { 2, 0, 0 }, *tile_2_2_0_0 },       //
                   GetTileDataAction{ { 2, 0, { 2, 0, 1 } }, NotFound },    // child tile, not found
                   GetTileDataAction{ { 2, 0, { 2, 1, 0 } }, NotFound },    // ...
                   GetTileDataAction{ { 2, 0, { 2, 1, 1 } }, NotFound },    // ...
                   GetTileDataAction{ { 0, 0, { 0, 0, 0 } }, Found },       // parent tile, found
-                  RetainTileDataAction{ { 0, 0, { 0, 0, 0 } }, Resource::Necessity::Optional }, //
+                  RetainTileDataAction{ { 0, 0, { 0, 0, 0 } }, TileNecessity::Optional }, //
                   RenderTileAction{ { 0, 0, 0 }, *tile_0_0_0_0 },       //
               }),
               log);
@@ -541,17 +541,17 @@ TEST(UpdateRenderables, PreferChildTiles) {
     EXPECT_EQ(ActionLog({
                   GetTileDataAction{ { 1, 0, { 1, 0, 0 } }, Found }, // ideal tile, not ready
                   // ideal tile was added in previous invocation, but is not yet ready
-                  RetainTileDataAction{ { 1, 0, { 1, 0, 0 } }, Resource::Necessity::Required }, //
+                  RetainTileDataAction{ { 1, 0, { 1, 0, 0 } }, TileNecessity::Required }, //
                   GetTileDataAction{ { 2, 0, { 2, 0, 0 } }, Found },       // child tile, found
-                  RetainTileDataAction{ { 2, 0, { 2, 0, 0 } }, Resource::Necessity::Optional }, //
+                  RetainTileDataAction{ { 2, 0, { 2, 0, 0 } }, TileNecessity::Optional }, //
                   RenderTileAction{ { 2, 0, 0 }, *tile_2_2_0_0 },       //
                   GetTileDataAction{ { 2, 0, { 2, 0, 1 } }, Found },       // ...
-                  RetainTileDataAction{ { 2, 0, { 2, 0, 1 } }, Resource::Necessity::Optional }, // ...
+                  RetainTileDataAction{ { 2, 0, { 2, 0, 1 } }, TileNecessity::Optional }, // ...
                   RenderTileAction{ { 2, 0, 1 }, *tile_2_2_0_1 },       //
                   GetTileDataAction{ { 2, 0, { 2, 1, 0 } }, NotFound },    // child tile, not found
                   GetTileDataAction{ { 2, 0, { 2, 1, 1 } }, NotFound },    // ...
                   GetTileDataAction{ { 0, 0, { 0, 0, 0 } }, Found },       // parent tile, found
-                  RetainTileDataAction{ { 0, 0, { 0, 0, 0 } }, Resource::Necessity::Optional }, //
+                  RetainTileDataAction{ { 0, 0, { 0, 0, 0 } }, TileNecessity::Optional }, //
                   RenderTileAction{ { 0, 0, 0 }, *tile_0_0_0_0 },       //
               }),
               log);
@@ -564,19 +564,19 @@ TEST(UpdateRenderables, PreferChildTiles) {
     EXPECT_EQ(ActionLog({
                   GetTileDataAction{ { 1, 0, { 1, 0, 0 } }, Found }, // ideal tile, not ready
                   // ideal tile was added in first invocation, but is not yet ready
-                  RetainTileDataAction{ { 1, 0, { 1, 0, 0 } }, Resource::Necessity::Required }, //
+                  RetainTileDataAction{ { 1, 0, { 1, 0, 0 } }, TileNecessity::Required }, //
                   GetTileDataAction{ { 2, 0, { 2, 0, 0 } }, Found },       // child tile, found
-                  RetainTileDataAction{ { 2, 0, { 2, 0, 0 } }, Resource::Necessity::Optional }, //
+                  RetainTileDataAction{ { 2, 0, { 2, 0, 0 } }, TileNecessity::Optional }, //
                   RenderTileAction{ { 2, 0, 0 }, *tile_2_2_0_0 },       //
                   GetTileDataAction{ { 2, 0, { 2, 0, 1 } }, Found },       // ...
-                  RetainTileDataAction{ { 2, 0, { 2, 0, 1 } }, Resource::Necessity::Optional }, //
+                  RetainTileDataAction{ { 2, 0, { 2, 0, 1 } }, TileNecessity::Optional }, //
                   RenderTileAction{ { 2, 0, 1 }, *tile_2_2_0_1 },       //
                   GetTileDataAction{ { 2, 0, { 2, 1, 0 } }, Found },       // ...
-                  RetainTileDataAction{ { 2, 0, { 2, 1, 0 } }, Resource::Necessity::Optional }, //
+                  RetainTileDataAction{ { 2, 0, { 2, 1, 0 } }, TileNecessity::Optional }, //
                   RenderTileAction{ { 2, 1, 0 }, *tile_2_2_1_0 },       //
                   GetTileDataAction{ { 2, 0, { 2, 1, 1 } }, NotFound },    // child tile, not found
                   GetTileDataAction{ { 0, 0, { 0, 0, 0 } }, Found },       // parent tile, found
-                  RetainTileDataAction{ { 0, 0, { 0, 0, 0 } }, Resource::Necessity::Optional }, //
+                  RetainTileDataAction{ { 0, 0, { 0, 0, 0 } }, TileNecessity::Optional }, //
                   RenderTileAction{ { 0, 0, 0 }, *tile_0_0_0_0 },       //
               }),
               log);
@@ -590,18 +590,18 @@ TEST(UpdateRenderables, PreferChildTiles) {
     EXPECT_EQ(ActionLog({
                   GetTileDataAction{ { 1, 0, { 1, 0, 0 } }, Found }, // ideal tile, not ready
                   // ideal tile was added in first invocation, but is not yet ready
-                  RetainTileDataAction{ { 1, 0, { 1, 0, 0 } }, Resource::Necessity::Required }, //
+                  RetainTileDataAction{ { 1, 0, { 1, 0, 0 } }, TileNecessity::Required }, //
                   GetTileDataAction{ { 2, 0, { 2, 0, 0 } }, Found },       // child tile, found
-                  RetainTileDataAction{ { 2, 0, { 2, 0, 0 } }, Resource::Necessity::Optional }, //
+                  RetainTileDataAction{ { 2, 0, { 2, 0, 0 } }, TileNecessity::Optional }, //
                   RenderTileAction{ { 2, 0, 0 }, *tile_2_2_0_0 },       //
                   GetTileDataAction{ { 2, 0, { 2, 0, 1 } }, Found },       // ...
-                  RetainTileDataAction{ { 2, 0, { 2, 0, 1 } }, Resource::Necessity::Optional }, //
+                  RetainTileDataAction{ { 2, 0, { 2, 0, 1 } }, TileNecessity::Optional }, //
                   RenderTileAction{ { 2, 0, 1 }, *tile_2_2_0_1 },       //
                   GetTileDataAction{ { 2, 0, { 2, 1, 0 } }, Found },       // ...
-                  RetainTileDataAction{ { 2, 0, { 2, 1, 0 } }, Resource::Necessity::Optional }, //
+                  RetainTileDataAction{ { 2, 0, { 2, 1, 0 } }, TileNecessity::Optional }, //
                   RenderTileAction{ { 2, 1, 0 }, *tile_2_2_1_0 },       //
                   GetTileDataAction{ { 2, 0, { 2, 1, 1 } }, Found },       // ...
-                  RetainTileDataAction{ { 2, 0, { 2, 1, 1 } }, Resource::Necessity::Optional }, //
+                  RetainTileDataAction{ { 2, 0, { 2, 1, 1 } }, TileNecessity::Optional }, //
                   RenderTileAction{ { 2, 1, 1 }, *tile_2_2_1_1 },       //
               }),
               log);
@@ -628,15 +628,15 @@ TEST(UpdateRenderables, UseParentAndChildTiles) {
     EXPECT_EQ(ActionLog({
                   GetTileDataAction{ { 1, 0, { 1, 0, 0 } }, NotFound },    // ideal tile, missing
                   CreateTileDataAction{ { 1, 0, { 1, 0, 0 } } },           //
-                  RetainTileDataAction{ { 1, 0, { 1, 0, 0 } }, Resource::Necessity::Required }, //
+                  RetainTileDataAction{ { 1, 0, { 1, 0, 0 } }, TileNecessity::Required }, //
                   GetTileDataAction{ { 2, 0, { 2, 0, 0 } }, Found },       // child tile
-                  RetainTileDataAction{ { 2, 0, { 2, 0, 0 } }, Resource::Necessity::Optional }, //
+                  RetainTileDataAction{ { 2, 0, { 2, 0, 0 } }, TileNecessity::Optional }, //
                   RenderTileAction{ { 2, 0, 0 }, *tile_2_2_0_0 },       //
                   GetTileDataAction{ { 2, 0, { 2, 0, 1 } }, NotFound },    //
                   GetTileDataAction{ { 2, 0, { 2, 1, 0 } }, NotFound },    //
                   GetTileDataAction{ { 2, 0, { 2, 1, 1 } }, NotFound },    //
                   GetTileDataAction{ { 0, 0, { 0, 0, 0 } }, Found },       // parent tile
-                  RetainTileDataAction{ { 0, 0, { 0, 0, 0 } }, Resource::Necessity::Optional }, //
+                  RetainTileDataAction{ { 0, 0, { 0, 0, 0 } }, TileNecessity::Optional }, //
                   RenderTileAction{ { 0, 0, 0 }, *tile_0_0_0_0 },       //
               }),
               log);
@@ -648,13 +648,13 @@ TEST(UpdateRenderables, UseParentAndChildTiles) {
                                  source.idealTiles, source.zoomRange, 1);
     EXPECT_EQ(ActionLog({
                   GetTileDataAction{ { 1, 0, { 1, 0, 0 } }, Found },       // ideal tile, not ready
-                  RetainTileDataAction{ { 1, 0, { 1, 0, 0 } }, Resource::Necessity::Required }, //
+                  RetainTileDataAction{ { 1, 0, { 1, 0, 0 } }, TileNecessity::Required }, //
                   GetTileDataAction{ { 2, 0, { 2, 0, 0 } }, NotFound },    //
                   GetTileDataAction{ { 2, 0, { 2, 0, 1 } }, NotFound },    //
                   GetTileDataAction{ { 2, 0, { 2, 1, 0 } }, NotFound },    //
                   GetTileDataAction{ { 2, 0, { 2, 1, 1 } }, NotFound },    //
                   GetTileDataAction{ { 0, 0, { 0, 0, 0 } }, Found },       // parent tile
-                  RetainTileDataAction{ { 0, 0, { 0, 0, 0 } }, Resource::Necessity::Optional }, //
+                  RetainTileDataAction{ { 0, 0, { 0, 0, 0 } }, TileNecessity::Optional }, //
                   RenderTileAction{ { 0, 0, 0 }, *tile_0_0_0_0 },       //
               }),
               log);
@@ -679,7 +679,7 @@ TEST(UpdateRenderables, DontUseTilesLowerThanMinzoom) {
     EXPECT_EQ(ActionLog({
                   GetTileDataAction{ { 2, 0, { 2, 0, 0 } }, NotFound },    // ideal tile, missing
                   CreateTileDataAction{ { 2, 0, { 2, 0, 0 } } },           //
-                  RetainTileDataAction{ { 2, 0, { 2, 0, 0 } }, Resource::Necessity::Required }, //
+                  RetainTileDataAction{ { 2, 0, { 2, 0, 0 } }, TileNecessity::Required }, //
                   GetTileDataAction{ { 3, 0, { 3, 0, 0 } }, NotFound },    //
                   GetTileDataAction{ { 3, 0, { 3, 0, 1 } }, NotFound },    //
                   GetTileDataAction{ { 3, 0, { 3, 1, 0 } }, NotFound },    //
@@ -709,7 +709,7 @@ TEST(UpdateRenderables, UseOverzoomedTileAfterMaxzoom) {
         ActionLog({
             GetTileDataAction{ { 2, 0, { 2, 0, 0 } }, NotFound },    // ideal tile, missing
             CreateTileDataAction{ { 2, 0, { 2, 0, 0 } } },           //
-            RetainTileDataAction{ { 2, 0, { 2, 0, 0 } }, Resource::Necessity::Required }, //
+            RetainTileDataAction{ { 2, 0, { 2, 0, 0 } }, TileNecessity::Required }, //
             GetTileDataAction{ { 3, 0, { 2, 0, 0 } }, NotFound },    // overzoomed tile, not children!
             GetTileDataAction{ { 1, 0, { 1, 0, 0 } }, NotFound },    //
             GetTileDataAction{ { 0, 0, { 0, 0, 0 } }, NotFound },    //
@@ -724,11 +724,11 @@ TEST(UpdateRenderables, UseOverzoomedTileAfterMaxzoom) {
     EXPECT_EQ(
         ActionLog({
             GetTileDataAction{ { 2, 0, { 2, 0, 0 } }, Found },       // ideal tile, missing
-            RetainTileDataAction{ { 2, 0, { 2, 0, 0 } }, Resource::Necessity::Required }, //
+            RetainTileDataAction{ { 2, 0, { 2, 0, 0 } }, TileNecessity::Required }, //
             GetTileDataAction{ { 3, 0, { 2, 0, 0 } }, NotFound },    // overzoomed tile, not children!
             GetTileDataAction{ { 1, 0, { 1, 0, 0 } }, NotFound },    //
             CreateTileDataAction{ { 1, 0, { 1, 0, 0 } } },           //
-            RetainTileDataAction{ { 1, 0, { 1, 0, 0 } }, Resource::Necessity::Optional }, //
+            RetainTileDataAction{ { 1, 0, { 1, 0, 0 } }, TileNecessity::Optional }, //
             GetTileDataAction{ { 0, 0, { 0, 0, 0 } }, NotFound },    //
         }),
         log);
@@ -742,10 +742,10 @@ TEST(UpdateRenderables, UseOverzoomedTileAfterMaxzoom) {
     EXPECT_EQ(ActionLog({
                   GetTileDataAction{ { 3, 0, { 2, 0, 0 } }, NotFound },    // ideal tile, missing
                   CreateTileDataAction{ { 3, 0, { 2, 0, 0 } } },           //
-                  RetainTileDataAction{ { 3, 0, { 2, 0, 0 } }, Resource::Necessity::Required }, //
+                  RetainTileDataAction{ { 3, 0, { 2, 0, 0 } }, TileNecessity::Required }, //
                   GetTileDataAction{ { 4, 0, { 2, 0, 0 } }, NotFound },    //
                   GetTileDataAction{ { 2, 0, { 2, 0, 0 } }, Found },       //
-                  RetainTileDataAction{ { 2, 0, { 2, 0, 0 } }, Resource::Necessity::Optional }, //
+                  RetainTileDataAction{ { 2, 0, { 2, 0, 0 } }, TileNecessity::Optional }, //
                   RenderTileAction{ { 2, 0, 0 }, *tile_2_2_0_0 },       //
               }),
               log);
@@ -758,7 +758,7 @@ TEST(UpdateRenderables, UseOverzoomedTileAfterMaxzoom) {
                                  source.idealTiles, source.zoomRange, 3);
     EXPECT_EQ(ActionLog({
                   GetTileDataAction{ { 3, 0, { 2, 0, 0 } }, Found },       //
-                  RetainTileDataAction{ { 3, 0, { 2, 0, 0 } }, Resource::Necessity::Required }, //
+                  RetainTileDataAction{ { 3, 0, { 2, 0, 0 } }, TileNecessity::Required }, //
                   RenderTileAction{ { 2, 0, 0 }, *tile_3_2_0_0 },       //
               }),
               log);
@@ -769,7 +769,7 @@ TEST(UpdateRenderables, UseOverzoomedTileAfterMaxzoom) {
                                  source.idealTiles, source.zoomRange, 2);
     EXPECT_EQ(ActionLog({
                   GetTileDataAction{ { 2, 0, { 2, 0, 0 } }, Found },       //
-                  RetainTileDataAction{ { 2, 0, { 2, 0, 0 } }, Resource::Necessity::Required }, //
+                  RetainTileDataAction{ { 2, 0, { 2, 0, 0 } }, TileNecessity::Required }, //
                   RenderTileAction{ { 2, 0, 0 }, *tile_2_2_0_0 },       //
               }),
               log);
@@ -785,9 +785,9 @@ TEST(UpdateRenderables, UseOverzoomedTileAfterMaxzoom) {
     EXPECT_EQ(ActionLog({
                   GetTileDataAction{ { 2, 0, { 2, 0, 0 } }, NotFound },    //
                   CreateTileDataAction{ { 2, 0, { 2, 0, 0 } } },           //
-                  RetainTileDataAction{ { 2, 0, { 2, 0, 0 } }, Resource::Necessity::Required }, //
+                  RetainTileDataAction{ { 2, 0, { 2, 0, 0 } }, TileNecessity::Required }, //
                   GetTileDataAction{ { 3, 0, { 2, 0, 0 } }, Found },       // use overzoomed tile!
-                  RetainTileDataAction{ { 3, 0, { 2, 0, 0 } }, Resource::Necessity::Optional }, //
+                  RetainTileDataAction{ { 3, 0, { 2, 0, 0 } }, TileNecessity::Optional }, //
                   RenderTileAction{ { 2, 0, 0 }, *tile_3_2_0_0 },       //
               }),
               log);
@@ -811,7 +811,7 @@ TEST(UpdateRenderables, AscendToNonOverzoomedTiles) {
                                  source.idealTiles, source.zoomRange, 3);
     EXPECT_EQ(ActionLog({
                   GetTileDataAction{ { 3, 0, { 2, 0, 0 } }, Found },       //
-                  RetainTileDataAction{ { 3, 0, { 2, 0, 0 } }, Resource::Necessity::Required }, //
+                  RetainTileDataAction{ { 3, 0, { 2, 0, 0 } }, TileNecessity::Required }, //
                   RenderTileAction{ { 2, 0, 0 }, *tile_3_2_0_0 },       //
               }),
               log);
@@ -827,10 +827,10 @@ TEST(UpdateRenderables, AscendToNonOverzoomedTiles) {
     EXPECT_EQ(ActionLog({
                   GetTileDataAction{ { 3, 0, { 2, 0, 0 } }, NotFound },    //
                   CreateTileDataAction{ { 3, 0, { 2, 0, 0 } } },           //
-                  RetainTileDataAction{ { 3, 0, { 2, 0, 0 } }, Resource::Necessity::Required }, //
+                  RetainTileDataAction{ { 3, 0, { 2, 0, 0 } }, TileNecessity::Required }, //
                   GetTileDataAction{ { 4, 0, { 2, 0, 0 } }, NotFound }, // prefer using a child first
                   GetTileDataAction{ { 2, 0, { 2, 0, 0 } }, Found },    //
-                  RetainTileDataAction{ { 2, 0, { 2, 0, 0 } }, Resource::Necessity::Optional }, //
+                  RetainTileDataAction{ { 2, 0, { 2, 0, 0 } }, TileNecessity::Optional }, //
                   RenderTileAction{ { 2, 0, 0 }, *tile_2_2_0_0 },       //
               }),
               log);
@@ -845,11 +845,11 @@ TEST(UpdateRenderables, AscendToNonOverzoomedTiles) {
                                  source.idealTiles, source.zoomRange, 3);
     EXPECT_EQ(ActionLog({
                   GetTileDataAction{ { 3, 0, { 2, 0, 0 } }, Found },       // ideal tile, not ready
-                  RetainTileDataAction{ { 3, 0, { 2, 0, 0 } }, Resource::Necessity::Required }, //
+                  RetainTileDataAction{ { 3, 0, { 2, 0, 0 } }, TileNecessity::Required }, //
                   GetTileDataAction{ { 4, 0, { 2, 0, 0 } }, NotFound },    //
                   GetTileDataAction{ { 2, 0, { 2, 0, 0 } }, NotFound },    //
                   GetTileDataAction{ { 1, 0, { 1, 0, 0 } }, Found },       //
-                  RetainTileDataAction{ { 1, 0, { 1, 0, 0 } }, Resource::Necessity::Optional }, //
+                  RetainTileDataAction{ { 1, 0, { 1, 0, 0 } }, TileNecessity::Optional }, //
                   RenderTileAction{ { 1, 0, 0 }, *tile_1_1_0_0 },       //
               }),
               log);
@@ -861,13 +861,13 @@ TEST(UpdateRenderables, AscendToNonOverzoomedTiles) {
                                  source.idealTiles, source.zoomRange, 3);
     EXPECT_EQ(ActionLog({
                   GetTileDataAction{ { 3, 0, { 2, 0, 0 } }, Found },       // ideal tile, not ready
-                  RetainTileDataAction{ { 3, 0, { 2, 0, 0 } }, Resource::Necessity::Required }, //
+                  RetainTileDataAction{ { 3, 0, { 2, 0, 0 } }, TileNecessity::Required }, //
                   GetTileDataAction{ { 4, 0, { 2, 0, 0 } }, NotFound },    //
                   GetTileDataAction{ { 2, 0, { 2, 0, 0 } }, NotFound },    //
                   CreateTileDataAction{ { 2, 0, { 2, 0, 0 } } },           //
-                  RetainTileDataAction{ { 2, 0, { 2, 0, 0 } }, Resource::Necessity::Optional }, //
+                  RetainTileDataAction{ { 2, 0, { 2, 0, 0 } }, TileNecessity::Optional }, //
                   GetTileDataAction{ { 1, 0, { 1, 0, 0 } }, Found },       //
-                  RetainTileDataAction{ { 1, 0, { 1, 0, 0 } }, Resource::Necessity::Optional }, //
+                  RetainTileDataAction{ { 1, 0, { 1, 0, 0 } }, TileNecessity::Optional }, //
                   RenderTileAction{ { 1, 0, 0 }, *tile_1_1_0_0 },       //
               }),
               log);
@@ -889,7 +889,7 @@ TEST(UpdateRenderables, DoNotAscendMultipleTimesIfNotFound) {
     EXPECT_EQ(ActionLog({
                   GetTileDataAction{ { 8, 0, { 8, 0, 0 } }, NotFound },    // ideal tile
                   CreateTileDataAction{ { 8, 0, { 8, 0, 0 } } },           //
-                  RetainTileDataAction{ { 8, 0, { 8, 0, 0 } }, Resource::Necessity::Required }, //
+                  RetainTileDataAction{ { 8, 0, { 8, 0, 0 } }, TileNecessity::Required }, //
                   GetTileDataAction{ { 9, 0, { 9, 0, 0 } }, NotFound },    // child tile
                   GetTileDataAction{ { 9, 0, { 9, 0, 1 } }, NotFound },    // ...
                   GetTileDataAction{ { 9, 0, { 9, 1, 0 } }, NotFound },    // ...
@@ -905,7 +905,7 @@ TEST(UpdateRenderables, DoNotAscendMultipleTimesIfNotFound) {
 
                   GetTileDataAction{ { 8, 0, { 8, 1, 0 } }, NotFound },    // ideal tile
                   CreateTileDataAction{ { 8, 0, { 8, 1, 0 } } },           //
-                  RetainTileDataAction{ { 8, 0, { 8, 1, 0 } }, Resource::Necessity::Required }, //
+                  RetainTileDataAction{ { 8, 0, { 8, 1, 0 } }, TileNecessity::Required }, //
                   GetTileDataAction{ { 9, 0, { 9, 2, 0 } }, NotFound },    // child tile
                   GetTileDataAction{ { 9, 0, { 9, 2, 1 } }, NotFound },    // ...
                   GetTileDataAction{ { 9, 0, { 9, 3, 0 } }, NotFound },    // ...
@@ -923,7 +923,7 @@ TEST(UpdateRenderables, DoNotAscendMultipleTimesIfNotFound) {
                                  source.idealTiles, source.zoomRange, 8);
     EXPECT_EQ(ActionLog({
                   GetTileDataAction{ { 8, 0, { 8, 0, 0 } }, Found },       // ideal tile, not ready
-                  RetainTileDataAction{ { 8, 0, { 8, 0, 0 } }, Resource::Necessity::Required }, //
+                  RetainTileDataAction{ { 8, 0, { 8, 0, 0 } }, TileNecessity::Required }, //
                   GetTileDataAction{ { 9, 0, { 9, 0, 0 } }, NotFound },    // child tile
                   GetTileDataAction{ { 9, 0, { 9, 0, 1 } }, NotFound },    // ...
                   GetTileDataAction{ { 9, 0, { 9, 1, 0 } }, NotFound },    // ...
@@ -932,11 +932,11 @@ TEST(UpdateRenderables, DoNotAscendMultipleTimesIfNotFound) {
                   GetTileDataAction{ { 6, 0, { 6, 0, 0 } }, NotFound },    // ...
                   GetTileDataAction{ { 5, 0, { 5, 0, 0 } }, NotFound },    // ...
                   GetTileDataAction{ { 4, 0, { 4, 0, 0 } }, Found },       // stops ascent
-                  RetainTileDataAction{ { 4, 0, { 4, 0, 0 } }, Resource::Necessity::Optional }, //
+                  RetainTileDataAction{ { 4, 0, { 4, 0, 0 } }, TileNecessity::Optional }, //
                   RenderTileAction{ { 4, 0, 0 }, *tile_4_0_0_0 },       //
 
                   GetTileDataAction{ { 8, 0, { 8, 1, 0 } }, Found },       // ideal tile, not ready
-                  RetainTileDataAction{ { 8, 0, { 8, 1, 0 } }, Resource::Necessity::Required }, //
+                  RetainTileDataAction{ { 8, 0, { 8, 1, 0 } }, TileNecessity::Required }, //
                   GetTileDataAction{ { 9, 0, { 9, 2, 0 } }, NotFound },    // child tile
                   GetTileDataAction{ { 9, 0, { 9, 2, 1 } }, NotFound },    // ...
                   GetTileDataAction{ { 9, 0, { 9, 3, 0 } }, NotFound },    // ...
@@ -963,13 +963,13 @@ TEST(UpdateRenderables, DontRetainUnusedNonIdealTiles) {
                                  source.idealTiles, source.zoomRange, 2);
     EXPECT_EQ(ActionLog({
                   GetTileDataAction{ { 2, 0, { 2, 0, 0 } }, Found },       // ideal tile, not ready
-                  RetainTileDataAction{ { 2, 0, { 2, 0, 0 } }, Resource::Necessity::Required }, //
+                  RetainTileDataAction{ { 2, 0, { 2, 0, 0 } }, TileNecessity::Required }, //
                   GetTileDataAction{ { 3, 0, { 3, 0, 0 } }, NotFound },    //
                   GetTileDataAction{ { 3, 0, { 3, 0, 1 } }, NotFound },    //
                   GetTileDataAction{ { 3, 0, { 3, 1, 0 } }, NotFound },    //
                   GetTileDataAction{ { 3, 0, { 3, 1, 1 } }, NotFound },    //
                   GetTileDataAction{ { 1, 0, { 1, 0, 0 } }, Found },       // parent tile, not ready
-                  RetainTileDataAction{ { 1, 0, { 1, 0, 0 } }, Resource::Necessity::Optional }, //
+                  RetainTileDataAction{ { 1, 0, { 1, 0, 0 } }, TileNecessity::Optional }, //
                   GetTileDataAction{ { 0, 0, { 0, 0, 0 } }, NotFound },    //
               }),
               log);
@@ -996,7 +996,7 @@ TEST(UpdateRenderables, WrappedTiles) {
     EXPECT_EQ(ActionLog({
                   GetTileDataAction{ { 1, -1, { 1, 1, 0 } }, NotFound },    // ideal tile 1/-1/0 (wrapped to -1)
                   CreateTileDataAction{ { 1, -1, { 1, 1, 0 } } },           //
-                  RetainTileDataAction{ { 1, -1, { 1, 1, 0 } }, Resource::Necessity::Required }, //
+                  RetainTileDataAction{ { 1, -1, { 1, 1, 0 } }, TileNecessity::Required }, //
                   GetTileDataAction{ { 2, -1, { 2, 2, 0 } }, NotFound },    //
                   GetTileDataAction{ { 2, -1, { 2, 2, 1 } }, NotFound },    //
                   GetTileDataAction{ { 2, -1, { 2, 3, 0 } }, NotFound },    //
@@ -1005,18 +1005,18 @@ TEST(UpdateRenderables, WrappedTiles) {
 
                   GetTileDataAction{ { 1, 0, { 1, 0, 0 } }, NotFound },    // ideal tile 1/0/0
                   CreateTileDataAction{ { 1, 0, { 1, 0, 0 } } },           //
-                  RetainTileDataAction{ { 1, 0, { 1, 0, 0 } }, Resource::Necessity::Required }, //
+                  RetainTileDataAction{ { 1, 0, { 1, 0, 0 } }, TileNecessity::Required }, //
                   GetTileDataAction{ { 2, 0, { 2, 0, 0 } }, NotFound },    //
                   GetTileDataAction{ { 2, 0, { 2, 0, 1 } }, NotFound },    //
                   GetTileDataAction{ { 2, 0, { 2, 1, 0 } }, NotFound },    //
                   GetTileDataAction{ { 2, 0, { 2, 1, 1 } }, NotFound },    //
                   GetTileDataAction{ { 0, 0, { 0, 0, 0 } }, Found },       //
-                  RetainTileDataAction{ { 0, 0, { 0, 0, 0 } }, Resource::Necessity::Optional }, //
+                  RetainTileDataAction{ { 0, 0, { 0, 0, 0 } }, TileNecessity::Optional }, //
                   RenderTileAction{ { 0, 0, 0 }, *tile_0_0_0_0 },       //
 
                   GetTileDataAction{ { 1, 0, { 1, 1, 0 } }, NotFound },       // ideal tile 1/1/0, doesn't match 1/-/1/0
                   CreateTileDataAction{ { 1, 0, { 1, 1, 0 } } },
-                  RetainTileDataAction{ { 1, 0, { 1, 1, 0 } }, Resource::Necessity::Required }, //
+                  RetainTileDataAction{ { 1, 0, { 1, 1, 0 } }, TileNecessity::Required }, //
                   GetTileDataAction{ { 2, 0, { 2, 2, 0 } }, NotFound },    //
                   GetTileDataAction{ { 2, 0, { 2, 2, 1 } }, NotFound },    //
                   GetTileDataAction{ { 2, 0, { 2, 3, 0 } }, NotFound },    //
@@ -1025,7 +1025,7 @@ TEST(UpdateRenderables, WrappedTiles) {
 
                   GetTileDataAction{ { 1, 1, { 1, 0, 0 } }, NotFound },       // ideal tile 1/2/0 (wrapped to 1)
                   CreateTileDataAction{ { 1, 1, { 1, 0, 0 } } },
-                  RetainTileDataAction{ { 1, 1, { 1, 0, 0 } }, Resource::Necessity::Required }, //
+                  RetainTileDataAction{ { 1, 1, { 1, 0, 0 } }, TileNecessity::Required }, //
                   GetTileDataAction{ { 2, 1, { 2, 0, 0 } }, NotFound },    //
                   GetTileDataAction{ { 2, 1, { 2, 0, 1 } }, NotFound },    //
                   GetTileDataAction{ { 2, 1, { 2, 1, 0 } }, NotFound },    //
@@ -1050,7 +1050,7 @@ TEST(UpdateRenderables, RepeatedRenderWithMissingOptionals) {
     EXPECT_EQ(ActionLog({
                   GetTileDataAction{ { 6, 0, { 6, 0, 0 } }, NotFound },    // ideal tile, not found
                   CreateTileDataAction{ { 6, 0, { 6, 0, 0 } } },           //
-                  RetainTileDataAction{ { 6, 0, { 6, 0, 0 } }, Resource::Necessity::Required }, //
+                  RetainTileDataAction{ { 6, 0, { 6, 0, 0 } }, TileNecessity::Required }, //
                   GetTileDataAction{ { 7, 0, { 7, 0, 0 } }, NotFound },    // children
                   GetTileDataAction{ { 7, 0, { 7, 0, 1 } }, NotFound },    // ...
                   GetTileDataAction{ { 7, 0, { 7, 1, 0 } }, NotFound },    // ...
@@ -1070,7 +1070,7 @@ TEST(UpdateRenderables, RepeatedRenderWithMissingOptionals) {
                                  source.idealTiles, source.zoomRange, 6);
     EXPECT_EQ(ActionLog({
                   GetTileDataAction{ { 6, 0, { 6, 0, 0 } }, Found },       // ideal tile, not ready
-                  RetainTileDataAction{ { 6, 0, { 6, 0, 0 } }, Resource::Necessity::Required }, //
+                  RetainTileDataAction{ { 6, 0, { 6, 0, 0 } }, TileNecessity::Required }, //
                   GetTileDataAction{ { 7, 0, { 7, 0, 0 } }, NotFound },    // children
                   GetTileDataAction{ { 7, 0, { 7, 0, 1 } }, NotFound },    // ...
                   GetTileDataAction{ { 7, 0, { 7, 1, 0 } }, NotFound },    // ...
@@ -1091,14 +1091,14 @@ TEST(UpdateRenderables, RepeatedRenderWithMissingOptionals) {
                                  source.idealTiles, source.zoomRange, 6);
     EXPECT_EQ(ActionLog({
                   GetTileDataAction{ { 6, 0, { 6, 0, 0 } }, Found },       // ideal tile, not ready
-                  RetainTileDataAction{ { 6, 0, { 6, 0, 0 } }, Resource::Necessity::Required }, //
+                  RetainTileDataAction{ { 6, 0, { 6, 0, 0 } }, TileNecessity::Required }, //
                   GetTileDataAction{ { 7, 0, { 7, 0, 0 } }, NotFound },    // children
                   GetTileDataAction{ { 7, 0, { 7, 0, 1 } }, NotFound },    // ...
                   GetTileDataAction{ { 7, 0, { 7, 1, 0 } }, NotFound },    // ...
                   GetTileDataAction{ { 7, 0, { 7, 1, 1 } }, NotFound },    // ...
                   GetTileDataAction{ { 5, 0, { 5, 0, 0 } }, NotFound },    // ascent
                   CreateTileDataAction{ { 5, 0, { 5, 0, 0 } } },           //
-                  RetainTileDataAction{ { 5, 0, { 5, 0, 0 } }, Resource::Necessity::Optional }, //
+                  RetainTileDataAction{ { 5, 0, { 5, 0, 0 } }, TileNecessity::Optional }, //
                   GetTileDataAction{ { 4, 0, { 4, 0, 0 } }, NotFound },    // ...
                   GetTileDataAction{ { 3, 0, { 3, 0, 0 } }, NotFound },    // ...
                   GetTileDataAction{ { 2, 0, { 2, 0, 0 } }, NotFound },    // ...
@@ -1113,13 +1113,13 @@ TEST(UpdateRenderables, RepeatedRenderWithMissingOptionals) {
                                  source.idealTiles, source.zoomRange, 6);
     EXPECT_EQ(ActionLog({
                   GetTileDataAction{ { 6, 0, { 6, 0, 0 } }, Found },       // ideal tile, not ready
-                  RetainTileDataAction{ { 6, 0, { 6, 0, 0 } }, Resource::Necessity::Required }, //
+                  RetainTileDataAction{ { 6, 0, { 6, 0, 0 } }, TileNecessity::Required }, //
                   GetTileDataAction{ { 7, 0, { 7, 0, 0 } }, NotFound },    // children
                   GetTileDataAction{ { 7, 0, { 7, 0, 1 } }, NotFound },    // ...
                   GetTileDataAction{ { 7, 0, { 7, 1, 0 } }, NotFound },    // ...
                   GetTileDataAction{ { 7, 0, { 7, 1, 1 } }, NotFound },    // ...
                   GetTileDataAction{ { 5, 0, { 5, 0, 0 } }, Found },       // ascent
-                  RetainTileDataAction{ { 5, 0, { 5, 0, 0 } }, Resource::Necessity::Optional }, //
+                  RetainTileDataAction{ { 5, 0, { 5, 0, 0 } }, TileNecessity::Optional }, //
                   GetTileDataAction{ { 4, 0, { 4, 0, 0 } }, NotFound },    // ...
                   GetTileDataAction{ { 3, 0, { 3, 0, 0 } }, NotFound },    // ...
                   GetTileDataAction{ { 2, 0, { 2, 0, 0 } }, NotFound },    // ...
@@ -1135,16 +1135,16 @@ TEST(UpdateRenderables, RepeatedRenderWithMissingOptionals) {
                                  source.idealTiles, source.zoomRange, 6);
     EXPECT_EQ(ActionLog({
                   GetTileDataAction{ { 6, 0, { 6, 0, 0 } }, Found },       // ideal tile, not ready
-                  RetainTileDataAction{ { 6, 0, { 6, 0, 0 } }, Resource::Necessity::Required }, //
+                  RetainTileDataAction{ { 6, 0, { 6, 0, 0 } }, TileNecessity::Required }, //
                   GetTileDataAction{ { 7, 0, { 7, 0, 0 } }, NotFound },    // children
                   GetTileDataAction{ { 7, 0, { 7, 0, 1 } }, NotFound },    // ...
                   GetTileDataAction{ { 7, 0, { 7, 1, 0 } }, NotFound },    // ...
                   GetTileDataAction{ { 7, 0, { 7, 1, 1 } }, NotFound },    // ...
                   GetTileDataAction{ { 5, 0, { 5, 0, 0 } }, Found },       // ascent
-                  RetainTileDataAction{ { 5, 0, { 5, 0, 0 } }, Resource::Necessity::Optional }, //
+                  RetainTileDataAction{ { 5, 0, { 5, 0, 0 } }, TileNecessity::Optional }, //
                   GetTileDataAction{ { 4, 0, { 4, 0, 0 } }, NotFound },    // ...
                   CreateTileDataAction{ { 4, 0, { 4, 0, 0 } } },           //
-                  RetainTileDataAction{ { 4, 0, { 4, 0, 0 } }, Resource::Necessity::Optional }, //
+                  RetainTileDataAction{ { 4, 0, { 4, 0, 0 } }, TileNecessity::Optional }, //
                   GetTileDataAction{ { 3, 0, { 3, 0, 0 } }, NotFound },    // ...
                   GetTileDataAction{ { 2, 0, { 2, 0, 0 } }, NotFound },    // ...
                   GetTileDataAction{ { 1, 0, { 1, 0, 0 } }, NotFound },    // ...
@@ -1159,18 +1159,18 @@ TEST(UpdateRenderables, RepeatedRenderWithMissingOptionals) {
                                  source.idealTiles, source.zoomRange, 6);
     EXPECT_EQ(ActionLog({
                   GetTileDataAction{ { 6, 0, { 6, 0, 0 } }, Found },       // ideal tile, not ready
-                  RetainTileDataAction{ { 6, 0, { 6, 0, 0 } }, Resource::Necessity::Required }, //
+                  RetainTileDataAction{ { 6, 0, { 6, 0, 0 } }, TileNecessity::Required }, //
                   GetTileDataAction{ { 7, 0, { 7, 0, 0 } }, NotFound },    // children
                   GetTileDataAction{ { 7, 0, { 7, 0, 1 } }, NotFound },    // ...
                   GetTileDataAction{ { 7, 0, { 7, 1, 0 } }, NotFound },    // ...
                   GetTileDataAction{ { 7, 0, { 7, 1, 1 } }, NotFound },    // ...
                   GetTileDataAction{ { 5, 0, { 5, 0, 0 } }, Found },       // ascent
-                  RetainTileDataAction{ { 5, 0, { 5, 0, 0 } }, Resource::Necessity::Optional }, //
+                  RetainTileDataAction{ { 5, 0, { 5, 0, 0 } }, TileNecessity::Optional }, //
                   GetTileDataAction{ { 4, 0, { 4, 0, 0 } }, Found },       // ...
-                  RetainTileDataAction{ { 4, 0, { 4, 0, 0 } }, Resource::Necessity::Optional }, //
+                  RetainTileDataAction{ { 4, 0, { 4, 0, 0 } }, TileNecessity::Optional }, //
                   GetTileDataAction{ { 3, 0, { 3, 0, 0 } }, NotFound },    // ...
                   CreateTileDataAction{ { 3, 0, { 3, 0, 0 } } },           //
-                  RetainTileDataAction{ { 3, 0, { 3, 0, 0 } }, Resource::Necessity::Optional }, //
+                  RetainTileDataAction{ { 3, 0, { 3, 0, 0 } }, TileNecessity::Optional }, //
                   GetTileDataAction{ { 2, 0, { 2, 0, 0 } }, NotFound },    // ...
                   GetTileDataAction{ { 1, 0, { 1, 0, 0 } }, NotFound },    // ...
                   GetTileDataAction{ { 0, 0, { 0, 0, 0 } }, NotFound },    // ...
@@ -1184,20 +1184,20 @@ TEST(UpdateRenderables, RepeatedRenderWithMissingOptionals) {
                                  source.idealTiles, source.zoomRange, 6);
     EXPECT_EQ(ActionLog({
                   GetTileDataAction{ { 6, 0, { 6, 0, 0 } }, Found },       // ideal tile, not ready
-                  RetainTileDataAction{ { 6, 0, { 6, 0, 0 } }, Resource::Necessity::Required }, //
+                  RetainTileDataAction{ { 6, 0, { 6, 0, 0 } }, TileNecessity::Required }, //
                   GetTileDataAction{ { 7, 0, { 7, 0, 0 } }, NotFound },    // children
                   GetTileDataAction{ { 7, 0, { 7, 0, 1 } }, NotFound },    // ...
                   GetTileDataAction{ { 7, 0, { 7, 1, 0 } }, NotFound },    // ...
                   GetTileDataAction{ { 7, 0, { 7, 1, 1 } }, NotFound },    // ...
                   GetTileDataAction{ { 5, 0, { 5, 0, 0 } }, Found },       // ascent
-                  RetainTileDataAction{ { 5, 0, { 5, 0, 0 } }, Resource::Necessity::Optional }, //
+                  RetainTileDataAction{ { 5, 0, { 5, 0, 0 } }, TileNecessity::Optional }, //
                   GetTileDataAction{ { 4, 0, { 4, 0, 0 } }, Found },       // ...
-                  RetainTileDataAction{ { 4, 0, { 4, 0, 0 } }, Resource::Necessity::Optional }, //
+                  RetainTileDataAction{ { 4, 0, { 4, 0, 0 } }, TileNecessity::Optional }, //
                   GetTileDataAction{ { 3, 0, { 3, 0, 0 } }, Found },       // ...
-                  RetainTileDataAction{ { 3, 0, { 3, 0, 0 } }, Resource::Necessity::Optional }, //
+                  RetainTileDataAction{ { 3, 0, { 3, 0, 0 } }, TileNecessity::Optional }, //
                   GetTileDataAction{ { 2, 0, { 2, 0, 0 } }, NotFound },    // ...
                   CreateTileDataAction{ { 2, 0, { 2, 0, 0 } } },           //
-                  RetainTileDataAction{ { 2, 0, { 2, 0, 0 } }, Resource::Necessity::Optional }, //
+                  RetainTileDataAction{ { 2, 0, { 2, 0, 0 } }, TileNecessity::Optional }, //
                   GetTileDataAction{ { 1, 0, { 1, 0, 0 } }, NotFound },    // ...
                   GetTileDataAction{ { 0, 0, { 0, 0, 0 } }, NotFound },    // ...
               }),
@@ -1211,17 +1211,17 @@ TEST(UpdateRenderables, RepeatedRenderWithMissingOptionals) {
                                  source.idealTiles, source.zoomRange, 6);
     EXPECT_EQ(ActionLog({
                   GetTileDataAction{ { 6, 0, { 6, 0, 0 } }, Found },       // ideal tile, not ready
-                  RetainTileDataAction{ { 6, 0, { 6, 0, 0 } }, Resource::Necessity::Required }, //
+                  RetainTileDataAction{ { 6, 0, { 6, 0, 0 } }, TileNecessity::Required }, //
                   GetTileDataAction{ { 7, 0, { 7, 0, 0 } }, NotFound },    // children
                   GetTileDataAction{ { 7, 0, { 7, 0, 1 } }, NotFound },    // ...
                   GetTileDataAction{ { 7, 0, { 7, 1, 0 } }, NotFound },    // ...
                   GetTileDataAction{ { 7, 0, { 7, 1, 1 } }, NotFound },    // ...
                   GetTileDataAction{ { 5, 0, { 5, 0, 0 } }, Found },       // ascent
-                  RetainTileDataAction{ { 5, 0, { 5, 0, 0 } }, Resource::Necessity::Optional }, //
+                  RetainTileDataAction{ { 5, 0, { 5, 0, 0 } }, TileNecessity::Optional }, //
                   GetTileDataAction{ { 4, 0, { 4, 0, 0 } }, Found },       // ...
-                  RetainTileDataAction{ { 4, 0, { 4, 0, 0 } }, Resource::Necessity::Optional }, //
+                  RetainTileDataAction{ { 4, 0, { 4, 0, 0 } }, TileNecessity::Optional }, //
                   GetTileDataAction{ { 3, 0, { 3, 0, 0 } }, Found },       // ...
-                  RetainTileDataAction{ { 3, 0, { 3, 0, 0 } }, Resource::Necessity::Optional }, //
+                  RetainTileDataAction{ { 3, 0, { 3, 0, 0 } }, TileNecessity::Optional }, //
                   RenderTileAction{ { 3, 0, 0 }, *tile_3_3_0_0 },       //
               }),
               log);
@@ -1246,11 +1246,11 @@ TEST(UpdateRenderables, LoadRequiredIfIdealTileCantBeFound) {
                                  source.idealTiles, source.zoomRange, 6);
     EXPECT_EQ(ActionLog({
                   GetTileDataAction{ { 6, 0, { 6, 0, 0 } }, Found }, // ideal tile, not found
-                  RetainTileDataAction{ { 6, 0, { 6, 0, 0 } }, Resource::Necessity::Required }, //
+                  RetainTileDataAction{ { 6, 0, { 6, 0, 0 } }, TileNecessity::Required }, //
                   GetTileDataAction{ { 7, 0, { 6, 0, 0 } }, NotFound }, // overzoomed child
                   GetTileDataAction{ { 5, 0, { 5, 0, 0 } }, NotFound }, // ascent
                   CreateTileDataAction{ { 5, 0, { 5, 0, 0 } } },
-                  RetainTileDataAction{ { 5, 0, { 5, 0, 0 } }, Resource::Necessity::Required },
+                  RetainTileDataAction{ { 5, 0, { 5, 0, 0 } }, TileNecessity::Required },
                   GetTileDataAction{ { 4, 0, { 4, 0, 0 } }, NotFound }, // ...
                   GetTileDataAction{ { 3, 0, { 3, 0, 0 } }, NotFound }, // ...
                   GetTileDataAction{ { 2, 0, { 2, 0, 0 } }, NotFound }, // ...
diff --git a/test/storage/default_file_source.test.cpp b/test/storage/default_file_source.test.cpp
index b5686b5ffe..c11d442270 100644
--- a/test/storage/default_file_source.test.cpp
+++ b/test/storage/default_file_source.test.cpp
@@ -251,7 +251,7 @@ TEST(DefaultFileSource, OptionalNonExpired) {
     util::RunLoop loop;
     DefaultFileSource fs(":memory:", ".");
 
-    const Resource optionalResource { Resource::Unknown, "http://127.0.0.1:3000/test", {}, Resource::Optional };
+    const Resource optionalResource { Resource::Unknown, "http://127.0.0.1:3000/test", {}, Resource::LoadingMethod::CacheOnly };
 
     using namespace std::chrono_literals;
 
@@ -281,7 +281,7 @@ TEST(DefaultFileSource, OptionalExpired) {
     util::RunLoop loop;
     DefaultFileSource fs(":memory:", ".");
 
-    const Resource optionalResource { Resource::Unknown, "http://127.0.0.1:3000/test", {}, Resource::Optional };
+    const Resource optionalResource { Resource::Unknown, "http://127.0.0.1:3000/test", {}, Resource::LoadingMethod::CacheOnly };
 
     using namespace std::chrono_literals;
 
@@ -327,7 +327,7 @@ TEST(DefaultFileSource, OptionalNotFound) {
     util::RunLoop loop;
     DefaultFileSource fs(":memory:", ".");
 
-    const Resource optionalResource { Resource::Unknown, "http://127.0.0.1:3000/test", {}, Resource::Optional };
+    const Resource optionalResource { Resource::Unknown, "http://127.0.0.1:3000/test", {}, Resource::LoadingMethod::CacheOnly };
 
     using namespace std::chrono_literals;
 
@@ -348,13 +348,13 @@ TEST(DefaultFileSource, OptionalNotFound) {
     loop.run();
 }
 
-// Test that we can make a request with etag data that doesn't first try to load
-// from cache like a regular request
+// Test that a network only request doesn't attempt to load data from the cache.
 TEST(DefaultFileSource, TEST_REQUIRES_SERVER(NoCacheRefreshEtagNotModified)) {
     util::RunLoop loop;
     DefaultFileSource fs(":memory:", ".");
 
     Resource resource { Resource::Unknown, "http://127.0.0.1:3000/revalidate-same" };
+    resource.loadingMethod = Resource::LoadingMethod::NetworkOnly;
     resource.priorEtag.emplace("snowfall");
 
     using namespace std::chrono_literals;
@@ -383,13 +383,13 @@ TEST(DefaultFileSource, TEST_REQUIRES_SERVER(NoCacheRefreshEtagNotModified)) {
     loop.run();
 }
 
-// Test that we can make a request with etag data that doesn't first try to load
-// from cache like a regular request
+// Test that a network only request doesn't attempt to load data from the cache.
 TEST(DefaultFileSource, TEST_REQUIRES_SERVER(NoCacheRefreshEtagModified)) {
     util::RunLoop loop;
     DefaultFileSource fs(":memory:", ".");
 
     Resource resource { Resource::Unknown, "http://127.0.0.1:3000/revalidate-same" };
+    resource.loadingMethod = Resource::LoadingMethod::NetworkOnly;
     resource.priorEtag.emplace("sunshine");
 
     using namespace std::chrono_literals;
@@ -418,15 +418,13 @@ TEST(DefaultFileSource, TEST_REQUIRES_SERVER(NoCacheRefreshEtagModified)) {
     loop.run();
 }
 
-// Test that we can make a request that doesn't first try to load
-// from cache like a regular request.
+// Test that a network only request doesn't attempt to load data from the cache.
 TEST(DefaultFileSource, TEST_REQUIRES_SERVER(NoCacheFull)) {
     util::RunLoop loop;
     DefaultFileSource fs(":memory:", ".");
 
     Resource resource { Resource::Unknown, "http://127.0.0.1:3000/revalidate-same" };
-    // Setting any prior field results in skipping the cache.
-    resource.priorExpires.emplace(Seconds(0));
+    resource.loadingMethod = Resource::LoadingMethod::NetworkOnly;
 
     using namespace std::chrono_literals;
 
@@ -461,6 +459,7 @@ TEST(DefaultFileSource, TEST_REQUIRES_SERVER(NoCacheRefreshModifiedNotModified))
     DefaultFileSource fs(":memory:", ".");
 
     Resource resource { Resource::Unknown, "http://127.0.0.1:3000/revalidate-modified" };
+    resource.loadingMethod = Resource::LoadingMethod::NetworkOnly;
     resource.priorModified.emplace(Seconds(1420070400)); // January 1, 2015
 
     using namespace std::chrono_literals;
@@ -496,6 +495,7 @@ TEST(DefaultFileSource, TEST_REQUIRES_SERVER(NoCacheRefreshModifiedModified)) {
     DefaultFileSource fs(":memory:", ".");
 
     Resource resource { Resource::Unknown, "http://127.0.0.1:3000/revalidate-modified" };
+    resource.loadingMethod = Resource::LoadingMethod::NetworkOnly;
     resource.priorModified.emplace(Seconds(1417392000)); // December 1, 2014
 
     using namespace std::chrono_literals;
@@ -578,7 +578,7 @@ TEST(DefaultFileSource, TEST_REQUIRES_SERVER(RespondToStaleMustRevalidate)) {
     DefaultFileSource fs(":memory:", ".");
 
     Resource resource { Resource::Unknown, "http://127.0.0.1:3000/revalidate-same" };
-    resource.necessity = Resource::Necessity::Optional;
+    resource.loadingMethod = Resource::LoadingMethod::CacheOnly;
 
     // using namespace std::chrono_literals;
 
@@ -621,7 +621,7 @@ TEST(DefaultFileSource, TEST_REQUIRES_SERVER(RespondToStaleMustRevalidate)) {
     // Now run this request again, with the data we gathered from the previous stale/unusable
     // request. We're replacing the data so that we can check that the DefaultFileSource doesn't
     // attempt another database access if we already have the value.
-    resource.necessity = Resource::Necessity::Required;
+    resource.loadingMethod = Resource::LoadingMethod::NetworkOnly;
     resource.priorData = std::make_shared<std::string>("Prior value");
 
     req = fs.request(resource, [&](Response res) {