Add all tests

Author: thomasrockhu-codecov

src/test/java/calculator/CalculatorTest.java

@@ -1,6 +1,6 @@
 package calculator;
 
-import static org.junit.Assert.*;
+import static org.junit.Assert.assertEquals;
 
 import org.junit.Test;
 
@@ -9,6 +9,38 @@ public class CalculatorTest {
 
   @Test
   public void testAdd() {
-    assertEquals(new Calculator().add(1, 1), 2, DELTA);
+    assertEquals(Calculator.add(1, 2), 3.0, DELTA);
+    assertEquals(Calculator.add(1.0, 2.0), 3.0, DELTA);
+    assertEquals(Calculator.add(0, 2.0), 2.0, DELTA);
+    assertEquals(Calculator.add(2.0, 0), 2.0, DELTA);
+    assertEquals(Calculator.add(-4, 2.0), -2.0, DELTA);
+  }
+
+  @Test
+  public void testSubtract() {
+    assertEquals(Calculator.subtract(1, 2), -1.0, DELTA);
+    assertEquals(Calculator.subtract(2, 1), 1.0, DELTA);
+    assertEquals(Calculator.subtract(1.0, 2.0), -1.0, DELTA);
+    assertEquals(Calculator.subtract(0, 2.0), -2.0, DELTA);
+    assertEquals(Calculator.subtract(2.0, 0), 2.0, DELTA);
+    assertEquals(Calculator.subtract(-4, 2.0), -6.0, DELTA);
+  }
+
+  @Test
+  public void testMultiply() {
+    assertEquals(Calculator.multiply(1, 2), 2.0, DELTA);
+    assertEquals(Calculator.multiply(1.0, 2.0), 2.0, DELTA);
+    assertEquals(Calculator.multiply(0, 2.0), 0.0, DELTA);
+    assertEquals(Calculator.multiply(2.0, 0), 0.0, DELTA);
+    assertEquals(Calculator.multiply(-4, 2.0), -8.0, DELTA);
+  }
+
+  @Test
+  public void testDivide() {
+    assertEquals(Calculator.divide(1, 2), 0.5, DELTA);
+    assertEquals(Calculator.divide(1.0, 2.0), 0.5, DELTA);
+    assertEquals(Calculator.divide(0, 2.0), 0, DELTA);
+    assertEquals(Calculator.divide(-4, 2.0), -2.0, DELTA);
+    // assertEquals(Calculator.divide(2.0, 0), 0.0, DELTA);
   }
 }