Fix for #498. Proferences throw error when tabs yml file is empty

speedwagon/config/tabs.py

@@ -20,7 +20,7 @@ def data(self) -> List[CustomTabData]:
         """Get the data for custom tabs."""
 
     @abc.abstractmethod
-    def save(self, tabs: List[CustomTabData]):
+    def save(self, tabs: List[CustomTabData]) -> None:
         """Get the data for custom tabs."""
 
 
@@ -55,6 +55,8 @@ def read_file(yaml_file: str) -> str:
 
     def decode_tab_settings_yml_data(self, data: str) -> Dict[str, List[str]]:
         """Decode tab settings yml data."""
+        if len(data) == 0:
+            return {}
         tabs_config_data = yaml.load(data, Loader=yaml.SafeLoader)
         if not isinstance(tabs_config_data, dict):
             raise speedwagon.exceptions.FileFormatError("Failed to parse file")
@@ -105,7 +107,7 @@ def data(self) -> List[CustomTabData]:
             for tab_name, workflow_names in yml_data.items()
         ]
 
-    def save(self, tabs: List[CustomTabData]):
+    def save(self, tabs: List[CustomTabData]) -> None:
         """Write tabs to a yaml file."""
         self.file_writer_strategy.save(self.yaml_file, tabs)
 

tests/test_config.py

@@ -28,7 +28,7 @@ def data_reader():
 
     def test_yaml_errors_throws_tab_load_failure(self, monkeypatch):
         def data_reader():
-            return ""
+            return "garblygoock"
 
         config_loader = \
             speedwagon.config.tabs.CustomTabsYamlConfig(yaml_file="myfaketabs.yml")
@@ -39,7 +39,7 @@ def data_reader():
 
     def test_file_format_error_throws_tab_load_failure(self, monkeypatch):
         def data_reader():
-            return ""
+            return "garblygoock"
 
         config_loader = \
             speedwagon.config.tabs.CustomTabsYamlConfig(yaml_file="myfaketabs.yml")
@@ -95,6 +95,11 @@ def test_save(self):
         config_loader.save([])
         assert config_loader.file_writer_strategy.save.called is True
 
+    def test_load_empty_file(self):
+        config_loader = \
+            speedwagon.config.tabs.CustomTabsYamlConfig(yaml_file="tabs.yml")
+        config_loader.file_reader_strategy.read_file = Mock(return_value="")
+        assert config_loader.data() == []
 
 class TestTabsWriteStrategy:
     def test_write_data_is_called(self, monkeypatch):

tests/test_startup.py

@@ -85,7 +85,10 @@ def test_missing_workflow(monkeypatch, capsys):
     load.__class__ = dict
     monkeypatch.setattr(yaml, "load", load)
     def read_file(*args, **kwargs):
-        return ""
+        return """
+current:
+- Medusa Preingest Curation
+"""
     monkeypatch.setattr(
         speedwagon.config.tabs.TabsYamlFileReader,
         "read_file",
@@ -116,10 +119,12 @@ def test_get_custom_tabs_loads_workflows_from_file(monkeypatch):
         ]
     }
     load = Mock(name="load", return_value=tabs_config_data)
-    load.__class__ = dict
     monkeypatch.setattr(yaml, "load", load)
     def read_file(*args, **kwargs):
-        return ""
+        return """
+my workflow:
+- spam
+"""
     monkeypatch.setattr(
         speedwagon.config.tabs.TabsYamlFileReader,
         "read_file",