Single component - covered.

calculator-1/src/main/java/com/codescene/calculator1/Calculator.java

@@ -15,6 +15,9 @@ public double calculate(double firstOperand, double secondOperand, char operator
             case ':':{
                 return divide(firstOperand,secondOperand);
             }
+            case '^':{
+                return square(firstOperand);
+            }
             default:
                 throw new IllegalArgumentException("Unsupported operation :"+operator);
         }
@@ -37,4 +40,8 @@ private double subtract(double firstOperand, double secondOperand) {
     private double add(double firstOperand, double secondOperand) {
         return firstOperand + secondOperand;
     }
+
+    private double square(double x) {
+        return x * x;
+    }
 }

calculator-1/src/test/java/com/codescene/calculator1/CalculatorTest.java

@@ -30,4 +30,12 @@ void divideSimple(){
         double result = calculator.calculate(1,1,':');
         Assertions.assertEquals(1,result);
     }
+
+    @Test
+    void squareSimple(){
+        // the signature isn't flexible so we repeat the same number twice
+        double result = calculator.calculate(10, 10, '^');
+        Assertions.assertEquals(100.0,result);
+    }
+
 }