Support loading closed config file descriptor.

Refactored fix supplied in #735 and added tests.

mkdocs/config/base.py

@@ -106,7 +106,11 @@ def _open_config_file(config_file):
     if config_file is None:
         config_file = os.path.abspath('mkdocs.yml')
 
-    log.debug("Loading configuration file: %s", config_file)
+    # If closed file descriptor, get file path to reopen later.
+    if hasattr(config_file, 'closed') and config_file.closed:
+        config_file = config_file.name
+
+    log.debug("Loading configuration file: {0}".format(config_file))
 
     # If it is a string, we can assume it is a path and attempt to open it.
     if isinstance(config_file, utils.string_types):
@@ -116,6 +120,9 @@ def _open_config_file(config_file):
             raise exceptions.ConfigurationError(
                 "Config file '{0}' does not exist.".format(config_file))
 
+    # Ensure file descriptor is at begining
+    config_file.seek(0)
+
     return config_file
 
 

mkdocs/tests/config/base_tests.py

@@ -35,12 +35,85 @@ class ConfigBaseTests(unittest.TestCase):
 
         self.assertEqual(len(warnings), 0)
 
-    def test_load_missing_required(self):
+    def test_load_from_file(self):
         """
         Users can explicitly set the config file using the '--config' option.
         Allows users to specify a config other than the default `mkdocs.yml`.
         """
 
+        config_file = tempfile.NamedTemporaryFile('w', delete=False)
+        try:
+            config_file.write("site_name: MkDocs Test\n")
+            config_file.flush()
+            config_file.close()
+
+            cfg = base.load_config(config_file=config_file.name)
+            self.assertIsInstance(cfg, base.Config)
+            self.assertEqual(cfg['site_name'], 'MkDocs Test')
+        finally:
+            os.remove(config_file.name)
+
+    def test_load_from_missing_file(self):
+
+        self.assertRaises(exceptions.ConfigurationError,
+                          base.load_config, config_file='missing_file.yml')
+
+    def test_load_from_open_file(self):
+        """
+        `load_config` can accept an open file descriptor.
+        """
+        
+        config_file = tempfile.NamedTemporaryFile('r+', delete=False)
+        try:
+            config_file.write("site_name: MkDocs Test\n")
+            config_file.flush()
+
+            cfg = base.load_config(config_file=config_file)
+            self.assertIsInstance(cfg, base.Config)
+            self.assertEqual(cfg['site_name'], 'MkDocs Test')
+            # load_config will always close the file
+            self.assertTrue(config_file.closed)
+        finally:
+            os.remove(config_file.name)
+
+    def test_load_from_closed_file(self):
+        """
+        The `serve` command with auto-reload may pass in a closed file descriptor.
+        Ensure `load_config` reloads the closed file.
+        """
+
+        config_file = tempfile.NamedTemporaryFile('w', delete=False)
+        try:
+            config_file.write("site_name: MkDocs Test\n")
+            config_file.flush()
+            config_file.close()
+
+            cfg = base.load_config(config_file=config_file)
+            self.assertIsInstance(cfg, base.Config)
+            self.assertEqual(cfg['site_name'], 'MkDocs Test')
+        finally:
+            os.remove(config_file.name)
+
+    def test_load_from_deleted_file(self):
+        """
+        Deleting the config file could trigger a server reload.
+        """
+
+        config_file = tempfile.NamedTemporaryFile('w', delete=False)
+        try:
+            config_file.write("site_name: MkDocs Test\n")
+            config_file.flush()
+            config_file.close()
+        finally:
+            os.remove(config_file.name)
+        self.assertRaises(exceptions.ConfigurationError,
+                          base.load_config, config_file=config_file)
+
+    def test_load_missing_required(self):
+        """
+        `site_name` is a required setting.
+        """
+
         config_file = tempfile.NamedTemporaryFile('w', delete=False)
         try:
             config_file.write(