Don't show children for JUnit 5 @TestTemplate tests that ran only once

[iloveeclipse]

Don't show children for JUnit 5 @TestTemplate tests that ran only once

When running JUnit 5 @TestTemplate tests, extra test suites are shown in the JUnit view to represent the tests in the template. Those suites introduce unnecessary noise when the template contains only one test - e.g. when repeating tests that failed.

This change adjusts TestSuiteElement.getChildren(), pruning each TestSuiteElement that has a single TestCaseElement child that is also a dynamic test.

import static org.junit.jupiter.api.Assertions.assertEquals;

import org.junit.Assume;
import org.junit.jupiter.api.MethodOrderer.MethodName;
import org.junit.jupiter.api.RepeatedTest;
import org.junit.jupiter.api.Test;
import org.junit.jupiter.api.TestMethodOrder;

@TestMethodOrder(MethodName.class)
public class TestTemplatesJunit5 {

	@Test
	public void testOkNoRepeats() throws Exception {
		Thread.sleep(500);
	}
	
	@RepeatedTest(value = 1)
	public void testOkOneRepeat() throws Exception {
		Thread.sleep(500);
	}

	@RepeatedTest(value = 2)
	public void testOkTwoRepeats() throws Exception {
		Thread.sleep(500);
	}
	
	@Test
	public void testWithErrorNoRepeats() throws Exception {
		doStupidThings(null);
	}
	
	@RepeatedTest(value = 1)
	public void testErrorOneRepeat() throws Exception {
		doStupidThings(null);
	}
	
	@RepeatedTest(value = 2)
	public void testErrorTwoRepeats() throws Exception {
		doStupidThings(null);
	}

	@Test
	public void testFailNoRepeats() throws Exception {
		assertEquals("expected", "observed");
	}
	
	@RepeatedTest(value = 1)
	public void testFailOneRepeat() throws Exception {
		assertEquals("expected", "observed");
	}

	@RepeatedTest(value = 2)
	public void testFailTwoRepeats() throws Exception {
		assertEquals("expected", "observed");
	}


	@RepeatedTest(value = 0)
	public void testWrongRepeat() throws Exception {
		Thread.sleep(500);
	}
	
	@Test
	public void testAssume() throws Exception {
		Assume.assumeFalse(true);
	}
	
	@RepeatedTest(value = 1)
	public void testAssumeOneRepeat() throws Exception {
		Assume.assumeFalse(true);
	}
	
	@RepeatedTest(value = 2)
	public void testAssumeTwoRepeats() throws Exception {
		Assume.assumeFalse(true);
	}
	
	private void doStupidThings(String arg) {
		arg.toString();
	}
	
}

Fixes #945

[trancexpress]

@iloveeclipse I would rather not have changes like this all over the view and model code. Better to revert and we'll adapt our use case to not have the problem in the first place.

There are also more problems that remain not adressed, such as the test count not being displayed properly. Or the view collapsing after each test, instead of showing proper expanded state. We are better off without the templated tests in our IDE, support for them is not good in multiple ways.

[iloveeclipse]

After merging revert in #1203 for RC1 the plan is to "revert the revert" & add this patch on top for 4.31 M1.