Add signal to QCollapsible (#142)

* add signal when toggle button is clicked

* emit signal when expand/collapse are called. emit bool. add to test.

* fix signal emission

Co-authored-by: Talley Lambert <talley.lambert@gmail.com>

src/superqt/collapsible/_collapsible.py

@@ -1,19 +1,31 @@
 """A collapsible widget to hide and unhide child widgets"""
 from typing import Optional
 
-from qtpy.QtCore import QEasingCurve, QEvent, QMargins, QObject, QPropertyAnimation, Qt
+from qtpy.QtCore import (
+    QEasingCurve,
+    QEvent,
+    QMargins,
+    QObject,
+    QPropertyAnimation,
+    Qt,
+    Signal,
+)
 from qtpy.QtWidgets import QFrame, QPushButton, QVBoxLayout, QWidget
 
 
 class QCollapsible(QFrame):
     """A collapsible widget to hide and unhide child widgets.
 
+    A signal is emitted when the widget is expanded (True) or collapsed (False).
+
     Based on https://stackoverflow.com/a/68141638
     """
 
     _EXPANDED = "▼  "
     _COLLAPSED = "▲  "
 
+    toggled = Signal(bool)
+
     def __init__(self, title: str = "", parent: Optional[QWidget] = None):
         super().__init__(parent)
         self._locked = False
@@ -123,6 +135,8 @@ class QCollapsible(QFrame):
         else:
             self._content.setMaximumHeight(_content_height if forward else 0)
 
+        self.toggled.emit(direction == QPropertyAnimation.Direction.Forward)
+
     def _toggle(self):
         self.expand() if self.isExpanded() else self.collapse()
 

tests/test_collapsible.py

@@ -1,6 +1,6 @@
 """A test module for testing collapsible"""
 
-from qtpy.QtCore import QEasingCurve
+from qtpy.QtCore import QEasingCurve, Qt
 from qtpy.QtWidgets import QPushButton
 
 from superqt import QCollapsible
@@ -85,3 +85,16 @@ def test_changing_text(qtbot):
     wdg.setText("Hi new text")
     assert wdg.text() == "Hi new text"
     assert wdg._toggle_btn.text() == QCollapsible._COLLAPSED + "Hi new text"
+
+
+def test_toggle_signal(qtbot):
+    """Test that signal is emitted when widget expanded/collapsed."""
+    wdg = QCollapsible()
+    with qtbot.waitSignal(wdg.toggled, timeout=500):
+        qtbot.mouseClick(wdg._toggle_btn, Qt.LeftButton)
+
+    with qtbot.waitSignal(wdg.toggled, timeout=500):
+        wdg.expand()
+
+    with qtbot.waitSignal(wdg.toggled, timeout=500):
+        wdg.collapse()