Add Variables.append()

2 files changed, 27 insertions, 0 deletions

diff --git a/yarnutils/vars.py b/yarnutils/vars.py
index 9349a2d..b221ba6 100644
--- a/yarnutils/vars.py
+++ b/yarnutils/vars.py
@@ -51,3 +51,12 @@ class Variables(object):
 
     def save(self):
         self._save(self._dict)
+
+    def append(self, key, value):
+        if key in self._dict:
+            if not isinstance(self[key], list):
+                raise Exception('Value for {} is not a list'.format(key))
+        if key not in self._dict:
+            self._dict[key] = []
+        self._dict[key].append(value)
+        self.save()
diff --git a/yarnutils/vars_tests.py b/yarnutils/vars_tests.py
index 821d2a5..b42a1eb 100644
--- a/yarnutils/vars_tests.py
+++ b/yarnutils/vars_tests.py
@@ -60,3 +60,21 @@ class VariablesTests(unittest.TestCase):
         vars2 = yarnutils.Variables(self.tempdir)
         self.assertEqual(vars1['foo'], vars2['foo'])
         self.assertEqual(vars2['foo'], [0])
+
+    def test_appends_to_unset_key(self):
+        vars = yarnutils.Variables(self.tempdir)
+        vars.append('foo', 0)
+        self.assertEqual(vars['foo'], [0])
+
+    def test_append_saves(self):
+        vars1 = yarnutils.Variables(self.tempdir)
+        vars1.append('foo', 0)
+        vars2 = yarnutils.Variables(self.tempdir)
+        self.assertEqual(vars1['foo'], vars2['foo'])
+        self.assertEqual(vars2['foo'], [0])
+
+    def test_append_gives_error_if_appending_to_nonlist_value(self):
+        vars = yarnutils.Variables(self.tempdir)
+        vars['foo'] = 0
+        with self.assertRaises(Exception):
+            vars.append('foo', 0)