chore: add test for MetadataFiles option

Signed-off-by: Pratyush singhal <psinghal20@gmail.com>

builder/googlecompute/config_test.go

@@ -431,6 +431,7 @@ func testConfig(t *testing.T) (config map[string]interface{}, tempAccountFile st
 		"image_licenses": []string{
 			"test-license",
 		},
+		"metadata_files": map[string]string{},
 		"zone":           "us-east1-a",
 	}
 
@@ -484,6 +485,21 @@ func testAccountFile(t *testing.T) string {
 	return tf.Name()
 }
 
+const testMetadataFileContent = `testMetadata`
+
+func testMetadataFile(t *testing.T) string {
+	tf, err := ioutil.TempFile("", "packer")
+	if err != nil {
+		t.Fatalf("err: %s", err)
+	}
+	defer tf.Close()
+	if _, err := tf.Write([]byte(testMetadataFileContent)); err != nil {
+		t.Fatalf("err: %s", err)
+	}
+
+	return tf.Name()
+}
+
 // This is just some dummy data that doesn't actually work (it was revoked
 // a long time ago).
 const testAccountContent = `{}`

builder/googlecompute/step_create_instance_test.go

@@ -325,3 +325,20 @@ func TestCreateInstanceMetadata_noPublicKey(t *testing.T) {
 	// ensure the ssh metadata hasn't changed
 	assert.Equal(t, metadata["sshKeys"], sshKeys, "Instance metadata should not have been modified")
 }
+
+func TestCreateInstanceMetadata_metadataFile(t *testing.T) {
+	state := testState(t)
+	c := state.Get("config").(*Config)
+	image := StubImage("test-image", "test-project", []string{}, 100)
+	content := testMetadataFileContent
+	fileName := testMetadataFile(t)
+	c.MetadataFiles["user-data"] = fileName
+
+	// create our metadata
+	metadata, err := c.createInstanceMetadata(image, "", state)
+
+	assert.True(t, err == nil, "Metadata creation should have succeeded.")
+
+	// ensure the user-data key in metadata is updated with file content
+	assert.Equal(t, metadata["user-data"], content, "user-data field of the instance metadata should have been updated.")
+}