Add cmdui test

This demos how to test UI parts with pytest-qt, including "clicking
buttons" instead of calling functions directly from within the tests.

datalad_gooey/tests/test_dataladcmd_ui.py

@@ -1,7 +1,50 @@
-from PySide6.QtWidgets import QWidget
+from PySide6.QtWidgets import (
+    QDialogButtonBox,
+    QPushButton
+)
+from PySide6.QtCore import Qt
+
 from ..dataladcmd_ui import GooeyDataladCmdUI
+from datalad.tests.utils_pytest import (
+    assert_equal,
+    assert_false,
+    assert_in,
+    assert_true,
+    with_tempfile,
+)
+
+from .utils import gooey_app
+
+
+@with_tempfile(mkdir=True)
+def test_GooeyDataladCmdUI(rootpath=None, *, qtbot):
+
+    with gooey_app(rootpath) as gooey:
+        qtbot.addWidget(gooey.main_window)
+        cmdui = GooeyDataladCmdUI(gooey, gooey.get_widget('cmdTab'))
+
+        cmdui.configure('wtf', {})
+
+        # command tab is set up:
+        assert_true(cmdui.pwidget.isEnabled())
+        assert_equal(gooey.get_widget('contextTabs').currentWidget().objectName(),
+                     "cmdTab")
+        assert_equal(cmdui._cmd_title.text().lower(), "wtf")
+
+        # click OK and see the correct signal:
+        buttonbox = cmdui.pwidget.findChild(QDialogButtonBox, 'cmdTabButtonBox')
+        ok_button = [b for b in buttonbox.findChildren(QPushButton)
+                     if b.text() == "OK"]
+        assert_equal(len(ok_button), 1)
+        ok_button = ok_button[0]
+
+        with qtbot.waitSignal(cmdui.configured_dataladcmd) as blocker:
+            qtbot.mouseClick(ok_button, Qt.LeftButton)
 
+        assert_equal(blocker.args[0], 'wtf')
+        assert_in("decor", blocker.args[1].keys())
 
-def test_GooeyDataladCmdUI():
-    parent = QWidget()
-    GooeyDataladCmdUI(None, parent)
+        # reset_form
+        cmdui.reset_form()
+        assert_equal(cmdui._cmd_title.text().lower(), "")
+        assert_false(cmdui.pwidget.isEnabled())

datalad_gooey/tests/utils.py

@@ -0,0 +1,15 @@
+from contextlib import contextmanager
+
+from datalad_gooey.app import GooeyApp
+
+
+@contextmanager
+def gooey_app(path):
+    # TODO: This should probably become a fixture
+    try:
+        gooey = GooeyApp(path)
+        gooey.main_window.show()
+        yield gooey
+    finally:
+        if gooey is not None:
+            gooey.deinit()