Migrate snippet generator tests from workflow-cps

[dwnusbaum]

It looks like tests pass and the snippet generator works correctly even without this override, so I'm not sure what it's for. If it turns out it is necessary, I'd like to add a test and/comment explaining what it is here for.

EDIT: In the end, just migrating some tests from workflow-cps, see jenkinsci/workflow-cps-plugin#304.

[jglick]

Create a freestyle project parameterized with a boolean parameter named x. Create a Pipeline job. In the Pipeline Syntax page, select build and type in parameterized in the Project to Build field. A checkbox labeled x will appear, and Generate Pipeline Script will produce

build job: 'parameterized', parameters: [booleanParam(name: 'x', value: false)]

With the newInstance override removed, the generated script is

build 'parameterized'

[jglick]

I think https://github.com/jenkinsci/workflow-cps-plugin/blob/609bc51d4cca65e8c851cdbc05a3f0efd8d60638/src/test/java/org/jenkinsci/plugins/workflow/cps/SnippetizerTest.java#L203-L238 are the relevant tests. Possibly I forgot to move them from jenkinsci/pipeline-plugin#69 + jenkinsci/pipeline-plugin#190 during the 2.x split. workflow-cps generates a test JAR so SnippetizerTester can be used from anywhere.

[dwnusbaum]

Now I'm extra confused, because SnippitizerTest.buildTriggerStep seems to pass with these changes (but using the UI directly shows the problem you described). Maybe my SNAPSHOT versions are messed up locally. EDIT: Seems to work fine even moving the test here, maybe a subtle issue with SnippetizerTester.assertRoundTrip?

[dwnusbaum]

I think https://github.com/jenkinsci/workflow-cps-plugin/blob/609bc51d4cca65e8c851cdbc05a3f0efd8d60638/src/test/java/org/jenkinsci/plugins/workflow/cps/SnippetizerTest.java#L203-L238 are the relevant tests

Ah, whoops, I missed those, was only looking at SnippetizerTest.buildTriggerStep, and they definitely catch the issue. I'll move them all here.