Merge pull request #3951 from bahti/BAEL-1663

asserting exceptions in junit4 and junit5 code sample added

testing-modules/junit-5/src/test/java/com/baeldung/exception/ExceptionAssertionTest.java

@@ -0,0 +1,23 @@
+package com.baeldung.exception;
+
+import static org.junit.jupiter.api.Assertions.assertThrows;
+
+import org.junit.jupiter.api.Test;
+
+public class ExceptionAssertionTest {
+    @Test
+    public void whenExceptionThrown_thenAssertionSucceeds() {
+        String test = null;
+        assertThrows(NullPointerException.class, () -> {
+            test.length();
+        });
+    }
+
+    @Test
+    public void whenDerivedExceptionThrown_thenAssertionSucceds() {
+        String test = null;
+        assertThrows(RuntimeException.class, () -> {
+            test.length();
+        });
+    }
+}

testing-modules/junit-5/src/test/java/com/baeldung/migration/junit4/ExceptionAssertionTest.java

@@ -0,0 +1,24 @@
+package com.baeldung.migration.junit4;
+
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.rules.ExpectedException;
+
+public class ExceptionAssertionTest {
+
+    @Rule
+    public ExpectedException exceptionRule = ExpectedException.none();
+
+    @Test(expected = NullPointerException.class)
+    public void whenExceptionThrown_thenExpectationSatisfied() {
+        String test = null;
+        test.length();
+    }
+
+    @Test
+    public void whenExceptionThrown_thenRuleIsApplied() {
+        exceptionRule.expect(NumberFormatException.class);
+        exceptionRule.expectMessage("For input string");
+        Integer.parseInt("1a");
+    }
+}