Commit unit tests for content-type order

Signed-off-by: Alex Ellis <alexellis2@gmail.com>

gateway/tests/proxy_test.go

@@ -0,0 +1,46 @@
+package tests
+
+import (
+	"net/http"
+	"testing"
+
+	"github.com/openfaas/faas/gateway/handlers"
+)
+
+func Test_GetContentType_UsesResponseValue(t *testing.T) {
+	request := http.Header{}
+	request.Add("Content-Type", "text/plain")
+	response := http.Header{}
+	response.Add("Content-Type", "text/html")
+
+	contentType := handlers.GetContentType(request, response, "default")
+	if contentType != response.Get("Content-Type") {
+		t.Errorf("Got: %s, want: %s", contentType, response.Get("Content-Type"))
+	}
+}
+
+func Test_GetContentType_UsesRequest_WhenResponseEmpty(t *testing.T) {
+	request := http.Header{}
+	request.Add("Content-Type", "text/plain")
+	response := http.Header{}
+	response.Add("Content-Type", "")
+
+	contentType := handlers.GetContentType(request, response, "default")
+	if contentType != request.Get("Content-Type") {
+		t.Errorf("Got: %s, want: %s", contentType, request.Get("Content-Type"))
+	}
+
+}
+
+func Test_GetContentType_UsesDefaultWhenRequestResponseEmpty(t *testing.T) {
+	request := http.Header{}
+	request.Add("Content-Type", "")
+	response := http.Header{}
+	response.Add("Content-Type", "")
+
+	contentType := handlers.GetContentType(request, response, "default")
+	if contentType != "default" {
+		t.Errorf("Got: %s, want: %s", contentType, "default")
+	}
+
+}