vertical_whitespace_between_cases gives false warning if blank line has whitespace

[BenStaveleyTaylor]

New Issue Checklist

• Updated SwiftLint to the latest version: 0.29.2
• I searched for existing GitHub issues

Describe the bug

The vertical_whitespace_between_cases rule flags a warning even when there is a blank line before the case or default keyword, if that blank line contains any white space. Totally whitespace lines should be accepted as being blank.

Explanation: Xcode tends to insert trailing whitespace when it formats text and its Text Editing preference for "Automatically trim trailing whitespace" is not reliable. We live in a world where there frequently is trailing whitespace and so we disable the trailing_whitespace rule.

Complete output when running SwiftLint, including the stack trace and command used

$ ./swiftlint --config swiftlint.yml
Loading configuration from 'swiftlint.yml'
Linting Swift files at paths 
Linting 'vertical_whitespace_between_cases.swift' (1/1)
/Users/bestave/Desktop/vertical_whitespace_between_cases/vertical_whitespace_between_cases.swift:9:1: warning: Vertical Whitespace Between Cases Violation: Include a single empty line between switch cases. (vertical_whitespace_between_cases)
Done linting! Found 1 violation, 0 serious in 1 file.

Environment

• SwiftLint version (run swiftlint version to be sure)? 0.29.2
• Installation method used (Homebrew, CocoaPods, building from source, etc)? CocoaPods
• Paste your configuration file:

disabled_rules:
  - trailing_whitespace
  
opt_in_rules:
  - vertical_whitespace_between_cases

• Are you using nested configurations? No
• Which Xcode version are you using? 10.1
• Do you have a sample that shows the issue?

enum Test {

    static func caseTest(value: Int) -> String {

        switch value {
        case 1:
            return "One"
         
        default:
            return "Not One"
        }
    }

}

Note: the blank line before default contains some trailing whitespace

[BenStaveleyTaylor]

vertical_whitespace_between_cases.zip

[marcelofabri]

@BenStaveleyTaylor this should be a good starter bug if you wanna try fixing it!

[BenStaveleyTaylor]

@marcelofabri OK, that's a challenge then :-) I'll have a go shortly...

[marcelofabri]

Let me know if you have any questions! You should only have to change VerticalWhitespaceBetweenCasesRule.swift, so definitely start there.

[BenStaveleyTaylor]

@marcelofabri Thanks. I haven't been a contributor on any open source projects before so the process is my main concern. Are there some guidelines for new contributors I can read?

[marcelofabri]

We have some documentation in CONTRIBUTING.MD, but feel free to ask any questions!