test: add tests for trigonometric functionalities

tests/test_gui.py

@@ -70,4 +70,21 @@ def test_expression_with_pow(self):
         self.assert_display("2**3")
         self.press_button("=")
         self.assert_display("8")
-
+
+    def test_expression_with_cos(self):
+        # cos(0) = 1
+        self.press_button("cos")
+        self.press_button("0")
+        self.press_button(")")
+        self.assert_display("cos(0)")
+        self.press_button("=")
+        self.assert_display("1")
+
+    def test_expression_with_sin(self):
+        # sin(0) = 0
+        self.press_button("sin")
+        self.press_button("0")
+        self.press_button(")")
+        self.assert_display("sin(0)")
+        self.press_button("=")
+        self.assert_display("0")

tests/test_model.py

@@ -89,3 +89,24 @@ def test_expression_with_pow(self):
         self.calculator.digit(3)
         self.assertEqual("(1+1)**3", self.calculator.expression)
         self.assertEqual(8, self.calculator.compute_result())
+
+    def test_cosine(self):
+        # cos(0) = 1
+        self.assertEqual("", self.calculator.expression)
+        self.calculator.cos()
+        self.assertEqual("cos(", self.calculator.expression)
+        self.calculator.digit(0)
+        self.calculator.close_parenthesis()
+        self.assertEqual("cos(0)", self.calculator.expression)
+        self.assertEqual(1, self.calculator.compute_result())
+
+    def test_sine(self):
+        # sin(0) = 0
+        self.assertEqual("", self.calculator.expression)
+        self.calculator.sin()
+        self.assertEqual("sin(", self.calculator.expression)
+        self.calculator.digit(0)
+        self.calculator.close_parenthesis()
+        self.assertEqual("sin(0)", self.calculator.expression)
+        self.assertEqual(0, self.calculator.compute_result())
+