JUnit5 tests work fine with maven but not when run through Eclipse, "No tests found with test runner 'JUnit 5'." - eclipse

Question

I'm getting a pop-up window with title "Could not run test" and message "No tests found with test runner 'JUnit 5'." when I try to run JUnit 5 tests with Eclipse via Run As > JUnit Test.
I have two test-related files. One is a test suite:
...
import org.junit.jupiter.api.BeforeAll;
import org.junit.platform.runner.JUnitPlatform;
import org.junit.platform.suite.api.SelectPackages;
import org.junit.runner.RunWith;
#RunWith(JUnitPlatform.class)
#SelectPackages("com.foo.stufftotest")
public class TestSuite {
#BeforeAll
public static void setup() {
...
The other contains the "actual" tests:
package com.foo.stufftotest;
import static org.junit.jupiter.api.Assertions.assertTrue;
import org.junit.jupiter.api.Test;
import com.foo.TestSuite;
import com.foo.business.mechanics.LogicStuff1;
public class BusinessTest {
#Test
public void testLogic1() {
...
}
#Test
public void testLogic2() {
...
}
...
All the testLogicN() methods depend on setup stuff done in TestSuite.setup(). If setup() doesn't run, there are a lot of null values, and it's no surprise that things fail. When I try to run JUnit from the project's context menu, all the tests are triggered and they all fail; the suite doesn't seem to be recognized. When I try to run JUnit specifically from TestSuite.java's context menu, I end up with the error I mentioned at the top of the question.
However, when I run maven test on the project, the suite is triggered properly, and all the tests pass. Therefore, the code itself doesn't seem to be the problem.
I don't remember having this issue with JUnit 4, although I never used JUnit 4 with this particular project.
Am I using Eclipse wrong, or am I using JUnit5 wrong? What's the fix here?

Answer 1

I encountered the same issue in Eclipse Oxygen 4.7.1 despite the fact that my unit tests were properly annotated with org.junit.jupiter.
I used the Maven > Update Project and selected Update project configuration from pom.xml but that did nothing even though I thought it would pick up the fact that I had JUnit5 dependencies in the pom.
My solution:
Open Java Build Path, select Libraries tab and Add Library.
Select JUnit.
Select JUnit5 for JUnit library version.
Once added I was able to manually execute tests from Eclipse. However I'm still not certain why this was not added automatically.

Answer 2

I'm getting a pop-up window with title "Could not run test" and message "No tests found with test runner 'JUnit 5'." when I try to run JUnit 5 tests with Eclipse via Run As > JUnit Test.
That's because TestSuite is in fact not a JUnit 5 test class. Since it is annotated with #RunWith (from JUnit 4) it is a JUnit 4 test class. To avoid the pop-up window in Eclipse, simply click on "Run Configurations" and select JUnit 4 instead of JUnit 5 for running the test class.
The other issue you have is that #BeforeAll is an annotation from JUnit Jupiter. Thus, it is simply not supported in a class annotated with #RunWith(JUnitPlatform.class) (unless that class also happens to contain #Test methods for JUnit Jupiter). Thus you will have to find an alternative approach to executing your "set up" code.