Remove PowerMock from the Slack GCF sample.

[saturnism]

Cherry-picked and rebased from @eamonnmcmanus's #2854

Instead of using Whitebox, use package-private constructor overloads
to supply the values needed by the test.

• I have followed Sample Format Guide
• pom.xml parent set to latest shared-configuration
• Appropriate changes to README are included in PR
• API's need to be enabled to test (tell us)
• Environment Variables need to be set (ask us to set them)
• Tests pass: mvn clean verify required
• Lint passes: mvn -P lint checkstyle:check required
• Static Analysis: mvn -P lint clean compile pmd:cpd-check spotbugs:check advisory only
• Please merge this PR for me once it is approved.

[lesv]

@saturnism Looks like there are both Lint issues and Java 11.
Please follow the suggestions in the template at the top.
Tests pass: mvn clean verify required
Lint passes: mvn -P lint checkstyle:check required
Static Analysis: mvn -P lint clean compile pmd:cpd-check spotbugs:check advisory only

[saturnism]

there is NPE from the tests during local run. any tricks to get the test running locally?

[saturnism]

Lint passes: mvn -P lint checkstyle:check required
Static Analysis: mvn -P lint clean compile pmd:cpd-check spotbugs:check advisory only

any way to simply add these into the compile phase, or add a profile to run these easily?

[saturnism]

also, i don't think those tests passed in the past. I'm getting

[ERROR] This use of java/util/logging/Logger.warning(Ljava/lang/String;)V might be used to include CRLF characters into log messages [functions.SlackSlashCommand] At SlackSlashCommand.java:[line 70] CRLF_INJECTION_LOGS

This line was not changed in the PR.

[ERROR] Class functions.SlackSlashCommand does not implement a toString method [functions.SlackSlashCommand] At SlackSlashCommand.java:[lines 40-210] IMC_IMMATURE_CLASS_NO_TOSTRING

Why does this class needs a ToString?

[saturnism]

need SLACK_TEST_SIGNATURE to test locally w/ verify. A unit test shouldn't depend on external values this way.

I think we also need KG_API_KEY and SLACK_SECRET.

[ace-n]

@saturnism followed up internally, check your email. 🙂

[saturnism]

Static Analysis failed with:

[ERROR] COMPILATION ERROR :
[ERROR] javac: invalid target release: 11

[lesv]

you can ignore static analysis, but not lint.

[saturnism]

@lesv all tests passing. i think there is a problem w/ the static analysis check due to jdk version. please merge, thnx!

[lesv]

That makes sense - we'll update that too.