HA1 Tim Tran 599383

src/main/java/htw/berlin/prog2/ha1/Calculator.java

@@ -83,6 +83,7 @@ public void pressUnaryOperationKey(String operation) {
         screen = Double.toString(result);
         if(screen.equals("NaN")) screen = "Error";
         if(screen.contains(".") && screen.length() > 11) screen = screen.substring(0, 10);
+        if(screen.endsWith(".0")) screen = screen.substring(0,screen.length()-2);
 
     }
 
@@ -118,6 +119,9 @@ public void pressNegativeKey() {
      * und das Ergebnis direkt angezeigt.
      */
     public void pressEqualsKey() {
+        if (latestOperation == null || latestOperation.isEmpty()) {
+            return;
+        }
         var result = switch(latestOperation) {
             case "+" -> latestValue + Double.parseDouble(screen);
             case "-" -> latestValue - Double.parseDouble(screen);

src/test/java/htw/berlin/prog2/ha1/CalculatorTest.java

@@ -90,5 +90,50 @@ void testMultipleDecimalDots() {
 
 
     //TODO hier weitere Tests erstellen
+
+    @Test
+    @DisplayName("should display negative number after pressing +/- key for a positive number")
+    void testNegativeKey() {
+        Calculator calc = new Calculator();
+
+        calc.pressDigitKey(1);
+        calc.pressNegativeKey();
+
+        String expected = "-1";
+        String actual = calc.readScreen();
+
+        assertEquals(expected, actual);
+    }
+
+    @Test
+    @DisplayName("should keep display unchanged when pressing = without prior operation")
+    void testEqualsKeyWithoutOperation() {
+        Calculator calc = new Calculator();
+
+        calc.pressDigitKey(4);
+        calc.pressEqualsKey();
+
+        String expected = "4";
+        String actual = calc.readScreen();
+
+        assertEquals(expected, actual);
+    }
+
+    @Test
+    @DisplayName("should display 1 after taking square root of one")
+    void testSquareRootOfOne() {
+        Calculator calc = new Calculator();
+
+        calc.pressDigitKey(1);
+        calc.pressUnaryOperationKey("√");
+
+        String expected = "1";
+        String actual = calc.readScreen();
+
+        assertEquals(expected, actual);
+    }
+
+
+
 }