BAEL-5210 JUnit fail assertions use cases (#11314)

Co-authored-by: Andres Luzuriaga <aluzuriaga@proofpoint.com>

testing-modules/junit-4/src/test/java/com/baeldung/junit/FailAssertionUnitTest.java

@@ -0,0 +1,72 @@
+package com.baeldung.junit;
+
+import org.junit.Ignore;
+import org.junit.Test;
+
+import java.util.Random;
+
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.fail;
+
+public class FailAssertionUnitTest {
+
+    public static final Random RANDOM = new Random();
+
+    @Test
+    @Ignore
+    public void incompleteTest() {
+        fail("Not yet implemented");
+    }
+
+    @Test
+    public void expectedException() {
+        try {
+            methodThrowsException();
+            fail("Expected exception was not thrown");
+        } catch (Exception e) {
+            assertNotNull(e);
+        }
+    }
+
+    @Test
+    public void unexpectedException() {
+        try {
+            safeMethod();
+            // more testing code
+        } catch (Exception e) {
+            fail("Unexpected exception was thrown");
+        }
+    }
+
+    @Test
+    public void testingCondition() {
+        int result = randomInteger();
+        if (result > Integer.MAX_VALUE) {
+            fail("Result cannot exceed integer max value");
+        }
+        // more testing code
+    }
+
+    @Test
+    public void returnBefore() {
+        int value = randomInteger();
+        for (int i = 0; i < 5; i++) {
+            // returns when (value + i) is an even number
+            if ((i + value) % 2 == 0) {
+                return;
+            }
+        }
+        fail("Should have returned before");
+    }
+
+    private void safeMethod() {
+    }
+
+    private void methodThrowsException() throws Exception {
+        throw new Exception();
+    }
+
+    private int randomInteger() {
+        return RANDOM.nextInt(Integer.MAX_VALUE);
+    }
+}

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

@@ -0,0 +1,50 @@
+package com.baeldung;
+
+import org.junit.jupiter.api.Disabled;
+import org.junit.jupiter.api.Test;
+
+import java.time.LocalDate;
+import java.time.format.DateTimeFormatter;
+import java.util.function.Supplier;
+import java.util.stream.Stream;
+
+import static org.junit.jupiter.api.Assertions.fail;
+
+public class FailAssertionUnitTest {
+
+    @Test
+    void failThrowable() {
+        try {
+            safeMethod();
+            // more testing code
+        } catch (Exception e) {
+            fail(e);
+        }
+    }
+
+    @Test
+    void failMessageThrowable() {
+        try {
+            safeMethod();
+            // more testing code
+        } catch (Exception e) {
+            fail("Unexpected exception was thrown", e);
+        }
+    }
+
+    @Test
+    @Disabled
+    void failMessageSupplier() {
+        Supplier<String> timedMessage = () -> DateTimeFormatter.ofPattern("yyyy-MM-dd").format(LocalDate.now());
+        fail(timedMessage);
+    }
+
+    @Test
+    void genericType() {
+        Stream.of().map(entry -> fail("should not be called"));
+    }
+
+    private void safeMethod() {
+        return;
+    }
+}