Qt API lazy load in qt_compat and qt_api config option

Fix #129

Author: nicoddemus

CHANGELOG.rst

@@ -11,7 +11,9 @@ New
   for ModelTester (`#63`_).
 
 * Now which Qt binding ``pytest-qt`` should use can be configured by the ``qt_api`` config option.
+  Thanks `@The-Compiler`_ for the request (`#129`_).
 
+.. _#129: https://github.com/pytest-dev/pytest-qt/issues/129
 .. _#134: https://github.com/pytest-dev/pytest-qt/issues/134
 .. _#63: https://github.com/pytest-dev/pytest-qt/pull/63
 

tests/test_basics.py

@@ -277,3 +277,34 @@ def test_parse_ini_boolean_invalid():
     import pytestqt.qtbot
     with pytest.raises(ValueError):
         pytestqt.qtbot._parse_ini_boolean('foo')
+
+
+@pytest.mark.parametrize('option_api', ['pyqt4', 'pyqt4v2', 'pyqt5', 'pyside'])
+def test_qt_api_ini_config(testdir, option_api):
+    """
+    Test qt_api ini option handling.
+    """
+    from pytestqt.qt_compat import qt_api
+
+    testdir.makeini("""
+        [pytest]
+        qt_api={option_api}
+    """.format(option_api=option_api))
+
+    testdir.makepyfile('''
+        import pytest
+
+        def test_foo(qtbot):
+            pass
+    ''')
+
+    result = testdir.runpytest_subprocess()
+    if option_api == qt_api.pytest_qt_api:
+        result.stdout.fnmatch_lines([
+            '* 1 passed in *'
+        ])
+    else:
+        result.stderr.fnmatch_lines([
+            '*ImportError:*'
+        ])
+