Ensure theme files do not override docs_dir files (#1672)

Fixes #1671.

Author: waylan

docs/about/release-notes.md

@@ -56,6 +56,7 @@ your global navigation uses more than one level, things will likely be broken.
 
 ### Other Changes and Additions to Version 1.1
 
+* Bugfix: Ensure theme files do not override `docs_dir` files (#1671).
 * Bugfix: Do not normalize URL fragments (#1655).
 * Add canonical tag to `readthedocs` theme (#1669).
 

mkdocs/structure/files.py

@@ -73,11 +73,13 @@ def filter(name):
                     return False
             return True
         for path in env.list_templates(filter_func=filter):
-            for dir in config['theme'].dirs:
-                # Find the first theme dir which contains path
-                if os.path.isfile(os.path.join(dir, path)):
-                    self.append(File(path, dir, config['site_dir'], config['use_directory_urls']))
-                    break
+            # Theme files do not override docs_dir files
+            if path not in self:
+                for dir in config['theme'].dirs:
+                    # Find the first theme dir which contains path
+                    if os.path.isfile(os.path.join(dir, path)):
+                        self.append(File(path, dir, config['site_dir'], config['use_directory_urls']))
+                        break
 
 
 class File(object):

mkdocs/tests/structure/file_tests.py

@@ -306,6 +306,34 @@ def test_files(self):
         self.assertTrue(extra_file.src_path in files)
         self.assertEqual(files.documentation_pages(), [fs[0], fs[1], extra_file])
 
+    @tempdir(files=[
+        'favicon.ico',
+        'index.md'
+    ])
+    @tempdir(files=[
+        'base.html',
+        'favicon.ico',
+        'style.css'
+    ])
+    def test_add_files_from_theme(self, tdir, ddir):
+        config = load_config(docs_dir=ddir, theme={'name': None, 'custom_dir': tdir})
+        env = config['theme'].get_env()
+        files = get_files(config)
+        self.assertEqual(
+            [file.src_path for file in files],
+            ['index.md', 'favicon.ico']
+        )
+        files.add_files_from_theme(env, config)
+        self.assertEqual(
+            [file.src_path for file in files],
+            ['index.md', 'favicon.ico', 'style.css']
+        )
+        # Ensure theme file does not override docs_dir file
+        self.assertEqual(
+            files.get_file_from_path('favicon.ico').abs_src_path,
+            os.path.normpath(os.path.join(ddir, 'favicon.ico'))
+        )
+
     def test_filter_paths(self):
         # Root level file
         self.assertFalse(_filter_paths('foo.md', 'foo.md', False, ['bar.md']))