Warning: Missing argument 3 for template_preprocess() for theme functions overridden by templates

#1: 2030457-1.patch queued for re-testing.

Thank you very much @Mark Carver! Test is looking very good, just found some tiny nitpicks:

+++ b/core/modules/system/lib/Drupal/system/Tests/Theme/ThemeTest.phpundefined
@@ -162,6 +162,14 @@ function testTemplateOverride() {
+    $this->assertText('Theme function overridden', 'Theme hook function overridden by defined \'template\'.');

Instead of escaping the single quotes, surround the assertion message in double quotes.

+++ b/core/modules/system/lib/Drupal/system/Tests/Theme/ThemeTest.phpundefined
@@ -162,6 +162,14 @@ function testTemplateOverride() {
+   * Ensures that a function only based theme hook can be overridden with a template.

For a summary line this is slightly too long, should fit in 80 characters. Additional description can be added in a paragraph below if needed, but this can probably just be shortened. See http://drupal.org/node/1354#functions.

+++ b/core/modules/system/lib/Drupal/system/Tests/Theme/ThemeTest.phpundefined
@@ -162,6 +162,14 @@ function testTemplateOverride() {
+    $this->assertText('Theme function overridden', 'Theme hook function overridden by defined \'template\'.');

+++ b/core/modules/system/tests/themes/test_theme/theme-test-function-template-override.html.twigundefined
@@ -0,0 +1,2 @@
+Theme function overridden

I would love for this test output to end in a period, just to make it consistent with other theme test output.

+++ b/core/modules/system/tests/modules/theme_test/theme_test.moduleundefined
@@ -97,6 +106,13 @@ function theme_test_template_test_page_callback() {
+  return theme('theme_test_function_template_override');

Please return a render array from the page callback :) See #2006152: [meta] Don't call theme() directly anywhere outside drupal_render().

Looking better :)

+++ b/core/modules/system/lib/Drupal/system/Tests/Theme/ThemeTest.phpundefined
@@ -162,11 +162,12 @@ function testTemplateOverride() {
+   * Ensures that a theme hook implemented via only a function can be
+   * successfully overridden with a template file from a theme.

+++ b/core/modules/system/tests/modules/theme_test/theme_test.moduleundefined
@@ -106,10 +106,14 @@ function theme_test_template_test_page_callback() {
+ * Menu callback for testing that a theme hook implemented via only a function
+ * can be overridden with a template file from a theme.

Both of these are now too long to be summary lines. Summary lines can't wrap - per https://drupal.org/node/1354#drupal "All summaries (first lines of docblocks) must be under 80 characters…"

+++ b/core/modules/system/tests/modules/theme_test/theme_test.moduleundefined
@@ -97,6 +106,17 @@ function theme_test_template_test_page_callback() {
+function theme_test_function_template_override_callback() {
+  $theme_test_function_template_override = array(
+    '#theme' => 'theme_test_function_template_override',
+  );
+  return drupal_render($theme_test_function_template_override);
+}

You don't need to drupal_render() here, you can just return a render array from the page callback. return array('#theme' => …);

I have no more nits to pick, this looks good to me. Thanks @Mark Carver!

Re-titling.

(double post)

Updated issue summary.

+++ b/core/modules/system/tests/modules/theme_test/lib/Drupal/theme_test/ThemeTestController.phpundefined
@@ -0,0 +1,34 @@
+  /**
+   * Creates the controller.
+   */
+  public static function create(ContainerInterface $container) {
+    return new static();
+  }

This docblock should just use {@inheritdoc}. Other than that, RTBC :)

Ref. https://drupal.org/node/1354#inheritdoc

Thanks, looks good :)

Updated issue summary.