Fix API error message and tests on Python 3.6

pytestqt/qt_compat.py

@@ -31,7 +31,7 @@ def _get_qt_api_from_env(self):
             api = api.lower()
             if api not in ('pyside', 'pyqt4', 'pyqt4v2', 'pyqt5'):  # pragma: no cover
                 msg = 'Invalid value for $PYTEST_QT_API: %s'
-                raise RuntimeError(msg % qt_api)
+                raise RuntimeError(msg % api)
         return api
 
     def _guess_qt_api(self):  # pragma: no cover

tests/test_basics.py

@@ -349,7 +349,30 @@ def test_foo(qtbot):
             '* 1 passed in *'
         ])
     else:
-        result.stderr.fnmatch_lines([
-            '*ImportError:*'
-        ])
+        try:
+            ModuleNotFoundError
+        except NameError:
+            # Python < 3.6
+            result.stderr.fnmatch_lines([
+                '*ImportError:*'
+            ])
+        else:
+            # Python >= 3.6
+            result.stderr.fnmatch_lines([
+                '*ModuleNotFoundError:*'
+            ])
+
+
+def test_invalid_qt_api_envvar(testdir, monkeypatch):
+    """
+    Make sure the error message with an invalid PYQTEST_QT_API is correct.
+    """
+    testdir.makepyfile('''
+        import pytest
 
+        def test_foo(qtbot):
+            pass
+    ''')
+    monkeypatch.setenv('PYTEST_QT_API', 'piecute')
+    result = testdir.runpytest_subprocess()
+    result.stderr.fnmatch_lines(['* Invalid value for $PYTEST_QT_API: piecute'])