Add tests for Command.run

tests/unit/commands/test_cmdutils.py

@@ -33,6 +33,19 @@ def clear_globals(monkeypatch):
     monkeypatch.setattr(cmdutils, 'aliases', [])
 
 
+def _get_cmd(*args, **kwargs):
+    """Get a command object created via @cmdutils.register.
+
+    Args:
+        Passed to @cmdutils.register decorator
+    """
+    @cmdutils.register(*args, **kwargs)
+    def fun():
+        """Blah."""
+        pass
+    return cmdutils.cmd_dict['fun']
+
+
 class TestCheckOverflow:
 
     def test_good(self):
@@ -351,3 +364,32 @@ class TestArgument:
                 pass
 
         assert str(excinfo.value) == "Argument marked as both count/win_id!"
+
+
+class TestRun:
+
+    @pytest.fixture(autouse=True)
+    def patching(self, mode_manager, fake_args):
+        fake_args.backend = 'webkit'
+
+    @pytest.mark.parametrize('backend, used, ok', [
+        (tabmod.Backend.QtWebEngine, 'webengine', True),
+        (tabmod.Backend.QtWebEngine, 'webkit', False),
+        (tabmod.Backend.QtWebKit, 'webengine', False),
+        (tabmod.Backend.QtWebKit, 'webkit', True),
+        (None, 'webengine', True),
+        (None, 'webkit', True),
+    ])
+    def test_backend(self, fake_args, backend, used, ok):
+        fake_args.backend = used
+        cmd = _get_cmd(backend=backend)
+        if ok:
+            cmd.run(win_id=0)
+        else:
+            with pytest.raises(cmdexc.PrerequisitesError) as excinfo:
+                cmd.run(win_id=0)
+            assert str(excinfo.value).endswith(' backend.')
+
+    def test_no_args(self):
+        cmd = _get_cmd()
+        cmd.run(win_id=0)