1 files changed, 30 insertions, 6 deletions
diff --git a/test/style/conversion/function.test.cpp b/test/style/conversion/function.test.cpp
index 1eff94d939..a48be2c075 100644
--- a/test/style/conversion/function.test.cpp
+++ b/test/style/conversion/function.test.cpp
@@ -1,9 +1,9 @@
 #include <mbgl/test/util.hpp>
 
-#include <mbgl/style/conversion.hpp>
-#include <mbgl/style/rapidjson_conversion.hpp>
+#include <mbgl/style/conversion/json.hpp>
 #include <mbgl/style/conversion/constant.hpp>
 #include <mbgl/style/conversion/function.hpp>
+#include <mbgl/style/conversion/data_driven_property_value.hpp>
 #include <mbgl/util/rapidjson.hpp>
 
 using namespace mbgl;
@@ -13,10 +13,8 @@ using namespace mbgl::style::conversion;
 TEST(StyleConversion, Function) {
     Error error;
 
-    auto parseFunction = [&](const std::string& src) {
-        JSDocument doc;
-        doc.Parse<0>(src);
-        return convert<CameraFunction<float>, JSValue>(doc, error);
+    auto parseFunction = [&](const std::string& json) {
+        return convertJSON<CameraFunction<float>>(json, error);
     };
 
     auto fn1 = parseFunction(R"({"stops":[]})");
@@ -54,3 +52,29 @@ TEST(StyleConversion, Function) {
     ASSERT_FALSE(fn9);
     ASSERT_EQ("function base must be a number", error.message);
 }
+
+TEST(StyleConversion, CompositeFunctionExpression) {
+    Error error;
+
+    auto parseFunction = [&](const std::string& src) {
+        JSDocument doc;
+        doc.Parse<0>(src);
+        return convert<DataDrivenPropertyValue<float>>(doc, error);
+    };
+
+    auto fn1 = parseFunction(R"(["interpolate", ["linear"], ["zoom"], 0, ["number", ["get", "x"]], 10, 10])");
+    ASSERT_TRUE(fn1);
+    
+    auto fn2 = parseFunction(R"(["coalesce", ["interpolate", ["linear"], ["zoom"], 0, ["number", ["get", "x"]], 10, 10], 0])");
+    ASSERT_TRUE(fn2);
+
+    auto fn3 = parseFunction(R"(["let", "a", 0, ["interpolate", ["linear"], ["zoom"], 0, ["number", ["get", "x"]], 10, 10] ])");
+    ASSERT_TRUE(fn3);
+
+    auto fn4 = parseFunction(R"(["coalesce", ["let", "a", 0, ["interpolate", ["linear"], ["zoom"], 0, ["number", ["get", "x"]], 10, 10], 0 ])");
+    ASSERT_TRUE(fn4);
+
+    auto fn5 = parseFunction(R"(["coalesce", ["interpolate", ["linear"], ["number", ["get", "x"]], 0, ["zoom"], 10, 10], 0])");
+    ASSERT_FALSE(fn5);
+    ASSERT_EQ(R"("zoom" expression may only be used as input to a top-level "step" or "interpolate" expression.)", error.message);
+}