Better config test coverage

core/pvhotwatercore/common/config/__init__.py

@@ -14,6 +14,9 @@
 from tomlkit.container import Container
 from tomlkit.items import Item
 
+# Valid config files will end with this
+VALID_CONFIG_EXTENSION = ".toml"
+
 
 class Config:
     """Represents a single config file.
@@ -74,13 +77,19 @@ def __init__(self, filename: str) -> None:
             filename (str): Filename of toml config file, without a path
 
         Raises:
-            ValueError: if filename contains a path separator
+            ValueError: if filename contains a path separator or does not have the
+                right extension
         """
         if os.sep in filename:
             raise ValueError("Filename cannot contain a path. "
                              "The config search path should be established statically"
                              "with Config.set_config_path()")
 
+        if not filename.endswith(VALID_CONFIG_EXTENSION):
+            raise ValueError(
+                f"The filename must end in {VALID_CONFIG_EXTENSION}."
+            )
+
         Config._CONFIG_PATH_ACCESSED = True
 
         self._conf_file_path: str = os.path.join(Config._CONFIG_PATH, filename)

core/pvhotwatercore/common/tests/test_config/test_config.py

@@ -118,3 +118,29 @@ def test_config_load(tmp_conf_path):
     assert a['Test']['a'] == 2
     assert a['Test']['b'] == "bumble"
     assert a['Test']['today']['napoleon']['plan'] == "whateverIFeelLikeGosh"
+
+
+def test_instantiation_with_fullpath():
+    with pytest.raises(ValueError):
+        config.Config("a" + os.sep + "b.toml")  # Contains os.sep
+
+    try:
+        assert config.Config("b.toml") is not None
+    except FileNotFoundError:
+        pass
+
+
+def test_instantiation_with_badext():
+    with pytest.raises(ValueError):
+        config.Config("test.conf")
+    with pytest.raises(ValueError):
+        config.Config("test.yaml")
+    with pytest.raises(ValueError):
+        config.Config("test.json")
+    with pytest.raises(ValueError):
+        config.Config("test.ini")
+
+    try:
+        assert config.Config("test.toml") is not None
+    except FileNotFoundError:
+        pass