test: Add unit tests for TerminalDisplay class

tests/test_terminal_display.py

@@ -0,0 +1,46 @@
+import unittest
+from src.xiwen.utils.terminal_display import (
+    get_TerminalDisplay_instance,
+    TerminalDisplay,
+)
+
+
+class TestTerminalDisplay(unittest.TestCase):
+    def test_references_to_TerminalDisplay(self):
+        """Test separate references are equal"""
+        A = TerminalDisplay()
+        B = TerminalDisplay()
+        self.assertEqual(A, B)
+
+    def test_one_TerminalDisplay_exists(self):
+        """Test just one instance exists despite multiple calls"""
+        A = TerminalDisplay()
+        B = TerminalDisplay()
+        self.assertIs(A, B._instance)
+
+    def test_TerminalDisplay_attributes_exist(self):
+        """Test TerminalDisplay has expected attributes"""
+        A = TerminalDisplay()
+        self.assertTrue(hasattr(A, "WELCOME_MESSAGE"))
+        self.assertTrue(hasattr(A, "MAIN_MENU_OPTIONS"))
+        self.assertTrue(hasattr(A, "DEMO_MESSAGE"))
+        self.assertTrue(hasattr(A, "EXPORT_OPTIONS"))
+        self.assertTrue(hasattr(A, "EXPORT_OPTIONS_FOR_CUSTOM_GRADES"))
+        self.assertTrue(hasattr(A, "UNKNOWN_CHARACTER_VARIANT"))
+
+
+class TestGetTerminalDisplayInstance(unittest.TestCase):
+    def test_instance_returned(self):
+        """Test function returns an TerminalDisplay instance"""
+        A = get_TerminalDisplay_instance()
+        self.assertTrue(isinstance(A, TerminalDisplay))
+
+    def test_returns_same_instance(self):
+        """Test multiple calls return same TerminalDisplay instance"""
+        A = get_TerminalDisplay_instance()
+        B = get_TerminalDisplay_instance()
+        self.assertIs(A, B._instance)
+
+
+if __name__ == "__main__":
+    unittest.main()