adding unit test for CodeclimateJSONFormatter

src/ansiblelint/formatters/__init__.py

@@ -149,8 +149,15 @@ def format(self, match: "MatchError") -> str:
 
 
 class CodeclimateJSONFormatter(BaseFormatter):
+    """Formatter for emitting violations in Codeclimate JSON report format.
+    Reference: https://github.com/codeclimate/platform/blob/master/spec/analyzers/SPEC.md#data-type
+    """
 
     def format(self, matches: List["MatchError"]) -> str:
+
+        if not isinstance(matches, list):
+            raise RuntimeError("The CodeclimatJSONFormatter was expecting a list of MatchError.")
+
         result = []
         for match in matches:
             issue = {}

test/TestCodeclimateJSONFormatter.py

@@ -0,0 +1,60 @@
+# Copyright (c) 2016 Will Thames <will@thames.id.au>
+#
+# Permission is hereby granted, free of charge, to any person obtaining a copy
+# of this software and associated documentation files (the "Software"), to deal
+# in the Software without restriction, including without limitation the rights
+# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+# copies of the Software, and to permit persons to whom the Software is
+# furnished to do so, subject to the following conditions:
+#
+# The above copyright notice and this permission notice shall be included in
+# all copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+# THE SOFTWARE.
+# pylint: disable=preferred-module  # FIXME: remove once migrated per GH-725
+import pathlib
+import json
+import unittest
+
+from ansiblelint.errors import MatchError
+from ansiblelint.formatters import CodeclimateJSONFormatter
+from ansiblelint.rules import AnsibleLintRule
+
+
+class TestCodeclimateJSONFormatter(unittest.TestCase):
+
+    def setUp(self):
+        self.rule = AnsibleLintRule()
+        self.rule.id = "TCF0001"
+        self.matches = []
+        self.matches.append(MatchError(
+            message="message",
+            linenumber=1,
+            details="hello",
+            filename="filename.yml",
+            rule=self.rule
+        ))
+        self.matches.append(MatchError(
+            message="message",
+            linenumber=2,
+            details="hello",
+            filename="filename.yml",
+            rule=self.rule
+        ))
+        self.formatter = CodeclimateJSONFormatter(pathlib.Path.cwd(), display_relative_path=True)
+
+    def test_format_list(self):
+        self.formatter.format(self.matches)
+
+    def test_result_is_json(self):
+        json.loads(self.formatter.format(self.matches))
+
+    def test_single_match(self):
+        with self.assertRaises(RuntimeError):
+            self.formatter.format(self.matches[0])