Fixes #161 -- is_default and has_value take into consideration value override set via environment variables

Author: jbasko

.bumpversion.cfg

@@ -1,5 +1,5 @@
 [bumpversion]
-current_version = 1.32.0
+current_version = 1.32.1
 commit = true
 tag = false
 

configmanager/__init__.py

@@ -1,4 +1,4 @@
-__version__ = '1.32.0'
+__version__ = '1.32.1'
 
 from .managers import Config
 from .items import Item

configmanager/items.py

@@ -175,23 +175,38 @@ def default(self, value):
             return
         self._default = self.type.deserialize(value)
 
+    def _get_envvar_value(self):
+        """
+        Internal helper to get item value from an environment variable
+        if item is controlled by one, and if the variable is set.
+
+        Returns not_set otherwise.
+        """
+        envvar_name = None
+
+        if self.envvar is True:
+            envvar_name = self.envvar_name
+            if envvar_name is None:
+                envvar_name = '_'.join(self.get_path()).upper()
+        elif self.envvar:
+            envvar_name = self.envvar
+
+        if envvar_name and envvar_name in os.environ:
+            return self.type.deserialize(os.environ[envvar_name])
+        else:
+            return not_set
+
     def get(self, fallback=not_set):
         """
         Returns config value.
 
         See Also:
             :meth:`.set` and :attr:`.value`
         """
-        if self.envvar:
-            if self.envvar is True:
-                envvar_name = self.envvar_name
-                if envvar_name is None:
-                    envvar_name = '_'.join(self.get_path()).upper()
-                if envvar_name in os.environ:
-                    return self.type.deserialize(os.environ[envvar_name])
-            else:
-                if self.envvar in os.environ:
-                    return self.type.deserialize(os.environ[self.envvar])
+
+        envvar_value = self._get_envvar_value()
+        if envvar_value is not not_set:
+            return envvar_value
 
         if self.has_value:
             if self._value is not not_set:
@@ -268,15 +283,26 @@ def reset(self):
     def is_default(self):
         """
         ``True`` if the item's value is its default value or if no value and no default value are set.
+
+        If the item is backed by an environment variable, this will be ``True`` only
+        if the environment variable is set and is different to the
+        default value of the item.
         """
-        return self._value is not_set or self._value == self.default
+        envvar_value = self._get_envvar_value()
+        if envvar_value is not not_set:
+            return envvar_value == self.default
+        else:
+            return self._value is not_set or self._value == self.default
 
     @property
     def has_value(self):
         """
         ``True`` if item has a default value or custom value set.
         """
-        return self.default is not not_set or self._value is not not_set
+        if self._get_envvar_value() is not not_set:
+            return True
+        else:
+            return self.default is not not_set or self._value is not not_set
 
     @property
     def section(self):

docs/index.rst

@@ -119,7 +119,7 @@ Similarly to reading, you find the appropriate persistence adapter, and use the
 
     config.json.dump('~/.config/helloworld/config.json', with_defaults=True)
 
-Unless you also pass ``with_defaults=True``, ::dump:: will not include items who don't have a custom value set.
+Unless you also pass ``with_defaults=True``, ``dump`` will exclude values for items who have no custom value set.
 
 How do I export all configuration values to a dictionary?
 ---------------------------------------------------------

tests/test_item.py

@@ -254,6 +254,17 @@ def test_is_default():
     assert e.is_default
 
 
+def test_is_default_respects_envvar(monkeypatch):
+    a = Item('a', default=5, envvar=True)
+    assert a.is_default
+
+    monkeypatch.setenv('A', '5')
+    assert a.is_default
+
+    monkeypatch.setenv('A', '6')
+    assert not a.is_default
+
+
 def test_has_value_returns_true_if_value_or_default_is_set():
     c = Item()
     assert not c.has_value
@@ -277,6 +288,14 @@ def test_has_value_returns_true_if_value_or_default_is_set():
     assert not e.has_value
 
 
+def test_has_value_respects_envvar(monkeypatch):
+    a = Item('a', envvar=True, type=int)
+    assert not a.has_value
+
+    monkeypatch.setenv('A', '5')
+    assert a.has_value
+
+
 def test_type_is_guessed_either_from_default_or_value():
     c = Item()
     assert c.type is Types.str