Strip junk after JSON return. (#15822)

Fixes #15601

test/units/plugins/action/test_action.py

@@ -33,6 +33,8 @@ try:
 except ImportError:
     import __builtin__ as builtins
 
+from nose.tools import eq_, raises
+
 from ansible.release import __version__ as ansible_version
 from ansible import constants as C
 from ansible.compat.six import text_type
@@ -630,3 +632,42 @@ class TestActionBase(unittest.TestCase):
             play_context.make_become_cmd.assert_called_once_with("ECHO SAME", executable=None)
         finally:
             C.BECOME_ALLOW_SAME_USER = become_allow_same_user
+
+# Note: Using nose's generator test cases here so we can't inherit from
+# unittest.TestCase
+class TestFilterNonJsonLines(object):
+    parsable_cases = (
+            (u'{"hello": "world"}', u'{"hello": "world"}'),
+            (u'{"hello": "world"}\n', u'{"hello": "world"}'),
+            (u'{"hello": "world"} ', u'{"hello": "world"} '),
+            (u'{"hello": "world"} \n', u'{"hello": "world"} '),
+            (u'Message of the Day\n{"hello": "world"}', u'{"hello": "world"}'),
+            (u'{"hello": "world"}\nEpilogue', u'{"hello": "world"}'),
+            (u'Several\nStrings\nbefore\n{"hello": "world"}\nAnd\nAfter\n', u'{"hello": "world"}'),
+            (u'{"hello": "world",\n"olá": "mundo"}', u'{"hello": "world",\n"olá": "mundo"}'),
+            (u'\nPrecedent\n{"hello": "world",\n"olá": "mundo"}\nAntecedent', u'{"hello": "world",\n"olá": "mundo"}'),
+            )
+
+    unparsable_cases = (
+            u'No json here',
+            u'"olá": "mundo"',
+            u'{"No json": "ending"',
+            u'{"wrong": "ending"]',
+            u'["wrong": "ending"}',
+            )
+
+    def check_filter_non_json_lines(self, stdout_line, parsed):
+        eq_(parsed, ActionBase._filter_non_json_lines(stdout_line))
+
+    def test_filter_non_json_lines(self):
+        for stdout_line, parsed in self.parsable_cases:
+            yield self.check_filter_non_json_lines, stdout_line, parsed
+
+    @raises(ValueError)
+    def check_unparsable_filter_non_json_lines(self, stdout_line):
+        ActionBase._filter_non_json_lines(stdout_line)
+
+    def test_unparsable_filter_non_json_lines(self):
+        for stdout_line in self.unparsable_cases:
+            yield self.check_unparsable_filter_non_json_lines, stdout_line
+