Fix spring test to properly handle failures

Failing test cases weren't not properly handled and instead caused
test to break. Added a test case and verified it works for both JUnit
and Spock.

spring-boot-cli/samples/failures.groovy

@@ -0,0 +1,37 @@
+class FailingJUnitTests {
+	@Test
+	void passingTest() {
+		assertTrue(true)
+	}
+
+	@Test
+	void failureByAssertion() {
+		assertTrue(false)
+	}
+
+	@Test
+	void failureByException() {
+		throw new RuntimeException("This should also be handled")
+	}
+}
+
+class FailingSpockTest extends Specification {
+	def "this should pass"() {
+		expect:
+		name.size() == length
+
+		where:
+		name    | length
+		"Spock" | 5
+	}
+
+	def "this should fail on purpose as well"() {
+		when:
+		String text = "Greetings"
+
+		then:
+		//throw new RuntimeException("This should fail!")
+		true == false
+	}
+
+}