Added unittest for tangentFunction

src/test/c/test_taschenrechner.c

@@ -126,6 +126,10 @@ void test_cosineFunction(void) {
     TEST_ASSERT_EQUAL_FLOAT(1.0, cosineFunction(0.0));
 }
 
-
+// Tangent function
+void test_tangentFunction(void) {
+    // Your test code here
+    TEST_ASSERT_EQUAL_FLOAT(0.0, tangentFunction(0.0));
+}
 
 #endif // TEST