In Eclipse: Could not find or load main class org.testng.remote.RemoteTestNG - eclipse

Question

Configuration
I have version 2019-12 (4.14.0) of Eclipse (having recently upgraded from 2019-03) with the following plugins installed (amongst others):
TestNG 6.14.3.201902250526
TestNG M2E (Maven) Integration (Optional) 6.14.3.201902250526
TestNG P2 Features 6.14.3.r201802240500
Eclipse is running against jdk1.8.0_152.
In Eclipse, my Java Build Path includes testng-6.14.3. I've tried to match the Eclipse plugin version against the version using in the project.
Under Properties -> TestNG I have all the default settings. There is no setting here for "Use Project TestNG.jar".
What Works
When I run tests from the command line with Gradle they all pass with no issue.
There are no complile errors showing in Eclipse.
What Does Not Work
When I run a test from Eclipse (by right clicking on a class) the console shows:
Error: Could not find or load main class org.testng.remote.RemoteTestNG
It appears I need a copy of testng-remote.jar. Should this have been installed as part of the plug-in, or am I meant to have included that in my build.gradle as a dependency?
Why can't I run tests from Eclipse? Do I need to install something further to resolve this error?
What I have Tried
I have tried removing and re-installing the TestNG plugin.

Answer 1

It seems you hit the bug https://bugs.eclipse.org/bugs/show_bug.cgi?id=558495 in Windows.
I reverted my version back to 2019-09 because of it.
The bug causes jars which should be on the classpath not to be on the classpath. This affects projects with long classpaths.

Answer 2

Can you try adding it in your build.gradle.
buildscript {
repositories {
mavenCentral()
}
dependencies {
classpath "io.spring.gradle:dependency-management-plugin:1.0.3.RELEASE"
classpath group: 'org.testng', name: 'testng', version: '6.8.+'
} }
Change the testng version as per your usage.

Answer 3

I don't remember such problem for gradle but it looks similar to the problem with testing on maven(with auto-build turned off). The soultion is to rebuild project (for maven it ia alt +f5) and because of such rebuilding - cache is updated.

Answer 4

You have detailed TestNG gradle tutorial
By default, Gradle will run all tests that it detects, which it does by inspecting the compiled test classes. When we specify useTestNG(), Gradle scans for all the methods annotated with #Test and execute them.
Example 1. Below is the basic configuration for the 'test' task
plugins {
id 'java'
}
group 'com.test'
version '1.0-SNAPSHOT'
sourceCompatibility = 1.8
repositories {
mavenCentral()
}
dependencies {
compile group: 'org.testng', name: 'testng', version: '6.14.3'
}
test {
useTestNG()
}
For Gradle use testCompile dependencies:
repositories {
jcenter()
}
dependencies {
testCompile 'org.testng:testng:6.10'
}
For specific version you have options,
Install from update site
Select Help / Install New Software...
Enter the update site URL in "Work with:" field:
Update site for release: http://dl.bintray.com/testng-team/testng-eclipse-release/.
Make sure the check box next to URL is checked and click Next.
Eclipse will then guide you through the process.
You can also install older versions of the plug-ins here. Note that the URL's on this page are update sites as well, not direct download links.
Build TestNG from source code
you can download the source and build the distribution yourself:
git clone git://github.com/cbeust/testng.git
cd testng
./build-with-gradle