[core] Return enum layer property values as string

The output of Layer::getProperty is a mapbox::base::Value which is
equivalent to JSON. When setting the value of an enum property via JSON
its value would be a string, so it would be natural to return a string
too.

Also, the numbers generated depend on the enum definition. They are not
part of the style spec.

1 files changed, 3 insertions, 3 deletions

diff --git a/test/map/map.test.cpp b/test/map/map.test.cpp
index 5872f4ecd5..6f0f126d3d 100644
--- a/test/map/map.test.cpp
+++ b/test/map/map.test.cpp
@@ -1006,6 +1006,6 @@ TEST(Map, UniversalStyleGetter) {
     StyleProperty lineCap = lineLayer->getProperty("line-cap");
     ASSERT_TRUE(lineCap.value);
     EXPECT_EQ(StyleProperty::Kind::Constant, lineCap.kind);
-    ASSERT_TRUE(lineCap.value.getInt());
-    EXPECT_EQ(mbgl::underlying_type(mbgl::style::LineCapType::Butt), *lineCap.value.getInt());
-}
\ No newline at end of file
+    ASSERT_TRUE(lineCap.value.getString());
+    EXPECT_EQ(std::string("butt"), *lineCap.value.getString());
+}