Add proper Media Type handling in js.Build

See #732

resources/resource_transformers/js/build_test.go

@@ -0,0 +1,69 @@
+// Copyright 2020 The Hugo Authors. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package js
+
+import (
+	"testing"
+
+	qt "github.com/frankban/quicktest"
+)
+
+// This test is added to test/warn against breaking the "stability" of the
+// cache key. It's sometimes needed to break this, but should be avoided if possible.
+func TestOptionKey(t *testing.T) {
+	c := qt.New(t)
+
+	opts := internalOptions{
+		TargetPath: "foo",
+	}
+
+	key := (&buildTransformation{options: opts}).Key()
+
+	c.Assert(key.Value(), qt.Equals, "jsbuild_9405671309963492201")
+}
+
+func TestToInternalOptions(t *testing.T) {
+	c := qt.New(t)
+
+	o := Options{
+		TargetPath:  "v1",
+		Target:      "v2",
+		JSXFactory:  "v3",
+		JSXFragment: "v4",
+		Externals:   []string{"react"},
+		Minify:      true,
+	}
+
+	c.Assert(toInternalOptions(o), qt.DeepEquals, internalOptions{
+		TargetPath:  "v1",
+		Minify:      true,
+		Target:      "v2",
+		JSXFactory:  "v3",
+		JSXFragment: "v4",
+		Externals:   []string{"react"},
+		Defines:     nil,
+		TSConfig:    "",
+	})
+
+	c.Assert(toInternalOptions(Options{}), qt.DeepEquals, internalOptions{
+		TargetPath:  "",
+		Minify:      false,
+		Target:      "esnext",
+		JSXFactory:  "",
+		JSXFragment: "",
+		Externals:   nil,
+		Defines:     nil,
+		TSConfig:    "",
+	})
+}