From c998e3ec486eeec68d7edb879026241539b7a806 Mon Sep 17 00:00:00 2001
From: appel_c <christian.appel@psi.ch>
Date: Thu, 19 Feb 2026 13:53:57 +0100
Subject: [PATCH] feat(bec-login): Add login widget in material design style

---
 bec_widgets/utils/bec_login.py           | 91 ++++++++++++++++++++++++
 tests/unit_tests/test_utils_bec_login.py | 52 ++++++++++++++
 2 files changed, 143 insertions(+)
 create mode 100644 bec_widgets/utils/bec_login.py
 create mode 100644 tests/unit_tests/test_utils_bec_login.py

diff --git a/bec_widgets/utils/bec_login.py b/bec_widgets/utils/bec_login.py
new file mode 100644
index 00000000..6f75b51c
--- /dev/null
+++ b/bec_widgets/utils/bec_login.py
@@ -0,0 +1,91 @@
+"""
+Login dialog for user authentication.
+The Login Widget is styled in a Material Design style and emits
+the entered credentials through a signal for further processing.
+"""
+
+from qtpy.QtCore import Qt, Signal
+from qtpy.QtWidgets import QLabel, QLineEdit, QPushButton, QVBoxLayout, QWidget
+
+
+class BECLogin(QWidget):
+    """Login dialog for user authentication in Material Design style."""
+
+    credentials_entered = Signal(str, str)
+
+    def __init__(self, parent=None):
+        super().__init__(parent=parent)
+        # Only displayed if this widget as standalone widget, and not embedded in another widget
+        self.setWindowTitle("Login")
+
+        title = QLabel("Sign in", parent=self)
+        title.setAlignment(Qt.AlignmentFlag.AlignCenter)
+        title.setStyleSheet(
+            """
+            #QLabel
+                {
+                    font-size: 18px;
+                    font-weight: 600;
+                }
+            """
+        )
+
+        self.username = QLineEdit(parent=self)
+        self.username.setPlaceholderText("Username")
+
+        self.password = QLineEdit(parent=self)
+        self.password.setPlaceholderText("Password")
+        self.password.setEchoMode(QLineEdit.EchoMode.Password)
+
+        self.ok_btn = QPushButton("Sign in", parent=self)
+        self.ok_btn.setDefault(True)
+        self.ok_btn.clicked.connect(self._emit_credentials)
+        # If the user presses Enter in the password field, trigger the OK button click
+        self.password.returnPressed.connect(self.ok_btn.click)
+
+        # Build Layout
+        layout = QVBoxLayout(self)
+        layout.setContentsMargins(32, 32, 32, 32)
+        layout.setSpacing(16)
+
+        layout.addWidget(title)
+        layout.addSpacing(8)
+        layout.addWidget(self.username)
+        layout.addWidget(self.password)
+        layout.addSpacing(12)
+        layout.addWidget(self.ok_btn)
+
+        self.username.setFocus()
+
+        self.setStyleSheet(
+            """
+            QLineEdit {
+                padding: 8px;
+            }
+            """
+        )
+
+    def _clear_password(self):
+        """Clear the password field."""
+        self.password.clear()
+
+    def _emit_credentials(self):
+        """Emit credentials and clear the password field."""
+        self.credentials_entered.emit(self.username.text().strip(), self.password.text())
+        self._clear_password()
+
+
+if __name__ == "__main__":  # pragma: no cover
+    import sys
+
+    from bec_qthemes import apply_theme
+    from qtpy.QtWidgets import QApplication
+
+    app = QApplication(sys.argv)
+    apply_theme("light")
+
+    dialog = BECLogin()
+
+    dialog.credentials_entered.connect(lambda u, p: print(f"Username: {u}, Password: {p}"))
+    dialog.show()
+    sys.exit(app.exec_())
diff --git a/tests/unit_tests/test_utils_bec_login.py b/tests/unit_tests/test_utils_bec_login.py
new file mode 100644
index 00000000..44fb59de
--- /dev/null
+++ b/tests/unit_tests/test_utils_bec_login.py
@@ -0,0 +1,52 @@
+"""Test the BEC Login widget"""
+
+import pytest
+from qtpy.QtCore import Qt
+from qtpy.QtWidgets import QLineEdit
+
+from bec_widgets.utils.bec_login import BECLogin
+
+
+@pytest.fixture
+def login_dialog(qtbot):
+    """Fixture to create a BECLogin instance."""
+    dialog = BECLogin()
+    qtbot.addWidget(dialog)
+    qtbot.waitExposed(dialog)  # Ensure the dialog is fully shown before running tests
+    return dialog
+
+
+def test_utils_login_dialog_initialization(login_dialog, qtbot):
+    """Test that the BECLogin initializes correctly."""
+    assert login_dialog.windowTitle() == "Login"
+    assert login_dialog.username.placeholderText() == "Username"
+    assert login_dialog.password.placeholderText() == "Password"
+    assert login_dialog.password.echoMode() == QLineEdit.EchoMode.Password
+    assert login_dialog.ok_btn.text() == "Sign in"
+
+    # Initially, this should be empty
+    with qtbot.waitSignal(login_dialog.credentials_entered, timeout=5000) as blocker:
+        qtbot.mouseClick(login_dialog.ok_btn, Qt.MouseButton.LeftButton)
+    assert blocker.args == ["", ""]
+
+
+def test_utils_login_dialog_emit_credentials(login_dialog, qtbot):
+    """Test that the BECLogin emits credentials correctly."""
+    test_username = "testuser "
+    test_password = "testpass"
+
+    login_dialog.username.setText(test_username)
+    login_dialog.password.setText(test_password)
+
+    with qtbot.waitSignal(login_dialog.credentials_entered, timeout=5000) as blocker:
+        qtbot.mouseClick(login_dialog.ok_btn, Qt.MouseButton.LeftButton)
+
+    assert blocker.args == [test_username.strip(), test_password]
+    assert login_dialog.password.text() == ""  # Password should be cleared after emitting
+
+    login_dialog.password.setText(test_password)
+    with qtbot.waitSignal(login_dialog.credentials_entered, timeout=5000) as blocker:
+        qtbot.keyClick(login_dialog.password, Qt.Key.Key_Return)
+
+    assert blocker.args == [test_username.strip(), test_password]
+    assert login_dialog.password.text() == ""  # Password should be cleared after emitting