Merge pull request #15279 from sk1418/negate-int

[negate-int] negate an int in java

core-java-modules/core-java-numbers-conversions/src/test/java/com/baeldung/negate/NegateIntUnitTest.java

@@ -0,0 +1,69 @@
+package com.baeldung.negate;
+
+import org.junit.jupiter.api.Test;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+public class NegateIntUnitTest {
+
+    private static final Logger LOG = LoggerFactory.getLogger(NegateIntUnitTest.class);
+
+    @Test
+    void whenUsingUnaryMinusOperator_thenGetExpectedResult() {
+        int x = 42;
+        assertEquals(-42, -x);
+
+        int z = 0;
+        assertEquals(0, -z);
+
+        int n = -42;
+        assertEquals(42, -n);
+    }
+
+    @Test
+    void whenUsingBitwiseComplementOperator_thenGetExpectedResult() {
+        int x = 42;
+        assertEquals(-42, ~x + 1);
+
+        int z = 0;
+        assertEquals(0, ~z + 1);
+
+        int n = -42;
+        assertEquals(42, ~n + 1);
+    }
+
+    @Test
+    void givenIntMinValue_whenUsingUnaryMinusOperator_thenCannotGetExpectedResult() {
+        int min = Integer.MIN_VALUE;
+        LOG.info("The value of '-min' is: " + -min);
+
+        assertTrue((-min) < 0);
+    }
+
+    @Test
+    void givenIntMinValue_whenUsingBitwiseComplementOperator_thenCannotGetExpectedResult() {
+        int min = Integer.MIN_VALUE;
+        int result = ~min + 1;
+        LOG.info("The value of '~min + 1' is: " + result);
+
+        assertTrue(result < 0);
+    }
+
+
+    @Test
+    void whenUsingUnaryMinusOperatorWithMinInt_thenGetExpectedResult() {
+        int x = 42;
+        assertEquals(-42, Math.negateExact(x));
+
+        int z = 0;
+        assertEquals(0, Math.negateExact(z));
+
+        int n = -42;
+        assertEquals(42, Math.negateExact(n));
+
+        int min = Integer.MIN_VALUE;
+        assertThrowsExactly(ArithmeticException.class, () -> Math.negateExact(min));
+    }
+}