1 files changed, 18 insertions, 0 deletions
diff --git a/yarnlib/block_parser_tests.py b/yarnlib/block_parser_tests.py
index 0a1d441..7051e17 100644
--- a/yarnlib/block_parser_tests.py
+++ b/yarnlib/block_parser_tests.py
@@ -104,3 +104,21 @@ class BlockParserTests(unittest.TestCase):
         self.assertEqual(impls[1].regexp, 'bar')
         self.assertEqual(impls[1].shell, 'cat /dev/null')
 
+    def test_raises_error_for_implements_with_no_args(self):
+        self.assertRaises(
+            yarnlib.BlockError,
+            self.parser.parse_blocks,
+            ['IMPLEMENTS'])
+
+    def test_raises_error_for_implements_with_one_args(self):
+        self.assertRaises(
+            yarnlib.BlockError,
+            self.parser.parse_blocks,
+            ['IMPLEMENTS GIVEN'])
+
+    def test_raises_error_for_implements_with_first_args_not_a_keyword(self):
+        self.assertRaises(
+            yarnlib.BlockError,
+            self.parser.parse_blocks,
+            ['IMPLEMENTS foo'])
+