[render-test] Add instruction for verifying file size

For a given absolute or relative path, measure the size of the file.

This is useful for measuring if the cache has increased as expected
after moving a camera or decreased after cleaning up.

In a more hackish manner, could be used for collecting binary size
statistics of shared libraries.

3 files changed, 98 insertions, 1 deletions

diff --git a/render-test/metadata.hpp b/render-test/metadata.hpp
index d25b81c7ab..e881bce208 100644
--- a/render-test/metadata.hpp
+++ b/render-test/metadata.hpp
@@ -31,6 +31,14 @@ struct TestPaths {
     }
 };
 
+struct FileSizeProbe {
+    FileSizeProbe() = default;
+    FileSizeProbe(std::string path_, uintmax_t size_) : path(std::move(path_)), size(size_) {}
+
+    std::string path;
+    uintmax_t size;
+};
+
 struct MemoryProbe {
     MemoryProbe() = default;
     MemoryProbe(size_t peak_, size_t allocations_)
@@ -43,7 +51,8 @@ struct MemoryProbe {
 
 class TestMetrics {
 public:
-    bool isEmpty() const { return memory.empty(); }
+    bool isEmpty() const { return fileSize.empty() && memory.empty(); }
+    std::map<std::string, FileSizeProbe> fileSize;
     std::map<std::string, MemoryProbe> memory;
 };
 
diff --git a/render-test/parser.cpp b/render-test/parser.cpp
index e9df704941..613fc566ea 100644
--- a/render-test/parser.cpp
+++ b/render-test/parser.cpp
@@ -273,6 +273,21 @@ std::string serializeMetrics(const TestMetrics& metrics) {
     rapidjson::Writer<rapidjson::StringBuffer> writer(s);
 
     writer.StartObject();
+
+    // Start fileSize section.
+    writer.Key("fileSize");
+    writer.StartArray();
+    for (const auto& fileSizeProbe : metrics.fileSize) {
+        assert(!fileSizeProbe.first.empty());
+        writer.StartArray();
+        writer.String(fileSizeProbe.first.c_str());
+        writer.String(fileSizeProbe.second.path);
+        writer.Uint64(fileSizeProbe.second.size);
+        writer.EndArray();
+    }
+    // End fileSize section.
+    writer.EndArray();
+
     // Start memory section.
     writer.Key("memory");
     writer.StartArray();
@@ -286,6 +301,7 @@ std::string serializeMetrics(const TestMetrics& metrics) {
     }
     // End memory section.
     writer.EndArray();
+
     writer.EndObject();
 
     return s.GetString();
@@ -439,6 +455,29 @@ TestMetrics readExpectedMetrics(const mbgl::filesystem::path& path) {
     }
 
     const auto& document = maybeJson.get<mbgl::JSDocument>();
+
+    if (document.HasMember("fileSize")) {
+        const mbgl::JSValue& fileSizeValue = document["fileSize"];
+        assert(fileSizeValue.IsArray());
+        for (auto& probeValue : fileSizeValue.GetArray()) {
+            assert(probeValue.IsArray());
+            assert(probeValue.Size() >= 3u);
+            assert(probeValue[0].IsString());
+            assert(probeValue[1].IsString());
+            assert(probeValue[2].IsNumber());
+
+            std::string mark{probeValue[0].GetString(), probeValue[0].GetStringLength()};
+            assert(!mark.empty());
+
+            std::string filePath{probeValue[1].GetString(), probeValue[1].GetStringLength()};
+            assert(!filePath.empty());
+
+            result.fileSize.emplace(std::piecewise_construct,
+                                    std::forward_as_tuple(std::move(mark)),
+                                    std::forward_as_tuple(std::move(filePath), probeValue[2].GetUint64()));
+        }
+    }
+
     if (document.HasMember("memory")) {
         const mbgl::JSValue& memoryValue = document["memory"];
         assert(memoryValue.IsArray());
diff --git a/render-test/runner.cpp b/render-test/runner.cpp
index 5df167431f..6b726a8eeb 100644
--- a/render-test/runner.cpp
+++ b/render-test/runner.cpp
@@ -242,6 +242,31 @@ bool TestRunner::checkRenderTestResults(mbgl::PremultipliedImage&& actualImage,
             break;
         }
     }
+    // Check file size metrics.
+    for (const auto& expected : metadata.expectedMetrics.fileSize) {
+        auto actual = metadata.metrics.fileSize.find(expected.first);
+        if (actual == metadata.metrics.fileSize.end()) {
+            metadata.errorMessage = "Failed to find fileSize probe: " + expected.first;
+            return false;
+        }
+        if (actual->second.path != expected.second.path) {
+            std::stringstream ss;
+            ss << "Comparing different files at probe \"" << expected.first << "\": " << actual->second.path
+               << ", expected is " << expected.second.path << ".";
+            metadata.errorMessage = ss.str();
+
+            return false;
+        }
+
+        if (actual->second.size != expected.second.size) {
+            std::stringstream ss;
+            ss << "File size does not match at probe \"" << expected.first << "\": " << actual->second.size
+               << ", expected is " << expected.second.size << ".";
+
+            metadata.errorMessage = ss.str();
+            return false;
+        }
+    }
     // Check memory metrics.
     for (const auto& expected : metadata.expectedMetrics.memory) {
         auto actual = metadata.metrics.memory.find(expected.first);
@@ -313,6 +338,7 @@ bool TestRunner::runOperations(const std::string& key, TestMetadata& metadata) {
     static const std::string removeSourceOp("removeSource");
     static const std::string setPaintPropertyOp("setPaintProperty");
     static const std::string setLayoutPropertyOp("setLayoutProperty");
+    static const std::string fileSizeProbeOp("probeFileSize");
     static const std::string memoryProbeOp("probeMemory");
     static const std::string memoryProbeStartOp("probeMemoryStart");
     static const std::string memoryProbeEndOp("probeMemoryEnd");
@@ -562,6 +588,29 @@ bool TestRunner::runOperations(const std::string& key, TestMetadata& metadata) {
             const mbgl::JSValue* propertyValue = &operationArray[3];
             layer->setLayoutProperty(propertyName, propertyValue);
         }
+    // probeFileSize
+    } else if (operationArray[0].GetString() == fileSizeProbeOp) {
+        assert(operationArray.Size() >= 3u);
+        assert(operationArray[1].IsString());
+        assert(operationArray[2].IsString());
+
+        std::string mark = std::string(operationArray[1].GetString(), operationArray[1].GetStringLength());
+        mbgl::filesystem::path path = std::string(operationArray[2].GetString(), operationArray[2].GetStringLength());
+        assert(!path.empty());
+
+        if (!path.is_absolute()) {
+            path = metadata.paths.defaultExpectations() / path;
+        }
+
+        if (mbgl::filesystem::exists(path)) {
+            auto size = mbgl::filesystem::file_size(path);
+            metadata.metrics.fileSize.emplace(std::piecewise_construct,
+                                              std::forward_as_tuple(std::move(mark)),
+                                              std::forward_as_tuple(std::move(path), size));
+        } else {
+            metadata.errorMessage = std::string("File not found: ") + path.string();
+            return false;
+        }
     // probeMemoryStart
     } else if (operationArray[0].GetString() == memoryProbeStartOp) {
         assert(!AllocationIndex::isActive());