Merge pull request #105 from mfelsche/m/traffic0

fix 400 errors on lizzy traffic

lizzy/apps/common.py

@@ -14,7 +14,8 @@ def __init__(self, application: str,
         self.extra_parameters = extra_parameters or []  # type: Iterable[str]
 
     def _execute(self, subcommand: str, *args: Iterable[str],
-                 expect_json: bool=False):
+                 expect_json: bool=False,
+                 accept_empty: bool=True):
         command = [self.application, subcommand]
         command.extend(self.extra_parameters)
         if expect_json:
@@ -30,11 +31,13 @@ def _execute(self, subcommand: str, *args: Iterable[str],
         stdout, _ = process.communicate()
         output = stdout.decode()
         if process.returncode == 0:
-            if expect_json:
+            if expect_json and (output or not accept_empty):
                 try:
                     return json.loads(output)
                 except ValueError:
                     raise ExecutionError('JSON ERROR', output)
+            elif not output and not accept_empty:
+                raise ExecutionError('EMPTY OUTPUT', output)
             else:
                 return output
         else:

tests/test_application.py

@@ -0,0 +1,70 @@
+import pytest
+from unittest.mock import MagicMock
+import json
+
+from lizzy.apps.common import Application
+from lizzy.exceptions import ExecutionError
+
+
+@pytest.fixture
+def popen(monkeypatch):
+    mock_popen = MagicMock()
+    mock_popen.return_value = mock_popen
+    mock_popen.returncode = 0
+    monkeypatch.setattr('lizzy.apps.common.Popen', mock_popen)
+    return mock_popen
+
+
+def test_json_output(monkeypatch, popen):
+    expected = {"foo": "bar"}
+    popen.communicate.return_value = json.dumps(expected).encode(), b'stderr'
+
+    app = Application("foo")
+    output = app._execute("bar", "a", "b", "c", expect_json=True, accept_empty=True)
+    assert output == expected
+
+    output = app._execute("bar", "a", "b", "c", expect_json=False, accept_empty=True)
+    assert output == json.dumps(expected)
+
+    output = app._execute("bar", "a", "b", "c", expect_json=True, accept_empty=False)
+    assert output == expected
+
+    output = app._execute("bar", "a", "b", "c", expect_json=False, accept_empty=False)
+    assert output == json.dumps(expected)
+
+
+def test_empty_output(monkeypatch, popen):
+    expected = ""
+    popen.communicate.return_value = expected.encode(), b'stderr'
+
+    app = Application("foo")
+
+    output = app._execute("bar", "a", "b", "c", expect_json=False, accept_empty=True)
+    assert output == expected
+
+    output = app._execute("bar", "a", "b", "c", expect_json=True, accept_empty=True)
+    assert output == expected
+
+    with pytest.raises(ExecutionError):
+        app._execute("bar", "a", "b", "c", expect_json=True, accept_empty=False)
+
+    with pytest.raises(ExecutionError):
+        app._execute("bar", "a", "b", "c", expect_json=False, accept_empty=False)
+
+
+def test_invalid_json_output(monkeypatch, popen):
+    expected = "[[}"
+    popen.communicate.return_value = expected.encode(), b'stderr'
+
+    app = Application("foo")
+    output = app._execute("bar", "a", "b", "c", expect_json=False, accept_empty=True)
+    assert output == expected
+
+    output = app._execute("bar", "a", "b", "c", expect_json=False, accept_empty=False)
+    assert output == expected
+
+    with pytest.raises(ExecutionError):
+        app._execute("bar", "a", "b", "c", expect_json=True, accept_empty=False)
+
+    with pytest.raises(ExecutionError):
+        app._execute("bar", "a", "b", "c", expect_json=True, accept_empty=True)