Allow explicit default with null value

readthedocs_build/config/config.py

@@ -376,6 +376,8 @@ def validate_requirements_file(self):
             return None
 
         requirements_file = self.raw_config['requirements_file']
+        if requirements_file is None:
+            return None
         base_path = os.path.dirname(self.source_file)
         with self.catch_validation_error('requirements_file'):
             validate_file(requirements_file, base_path)

readthedocs_build/config/test_config.py

@@ -49,6 +49,15 @@
 }
 
 
+config_with_explicit_defaults = {
+    'readthedocs.yml': '''
+name: docs
+type: sphinx
+requirements_file: null
+'''
+}
+
+
 multiple_config_dir = {
     'readthedocs.yml': '''
 name: first
@@ -113,6 +122,13 @@ def test_build_config_has_source_position(tmpdir):
     assert second.source_position == 1
 
 
+def test_build_config_has_explicit_default_null_value(tmpdir):
+    base = str(apply_fs(tmpdir, config_with_explicit_defaults))
+    build = load(base, env_config)[0]
+    assert isinstance(build, BuildConfig)
+    assert 'requirements_file' not in build
+
+
 def test_build_config_has_list_with_single_null_value(tmpdir):
     base = str(apply_fs(tmpdir, config_with_explicit_empty_list))
     build = load(base, env_config)[0]

readthedocs_build/config/test_parser.py

@@ -31,6 +31,24 @@ def test_parse_single_config():
     assert config[0]['base'] == 'path'
 
 
+def test_parse_null_value():
+    buf = StringIO(u'base: null')
+    config = parse(buf)
+    assert config[0]['base'] is None
+
+
+def test_parse_empty_value():
+    buf = StringIO(u'base:')
+    config = parse(buf)
+    assert config[0]['base'] is None
+
+
+def test_parse_empty_string_value():
+    buf = StringIO(u'base: ""')
+    config = parse(buf)
+    assert config[0]['base'] is ''
+
+
 def test_parse_empty_list():
     buf = StringIO(u'base: []')
     config = parse(buf)