feat(ignore patterns): add "ignorePatterns" config option

[nicojs]

Add the ability to specify ignorePatterns in your Stryker configuration. This replaces files option which is now deprecated.

By specifying ignorePatterns you choose which files should not be copied to the Sandbox directory (inside the .stryker-tmp directory). This effectively excludes them from being used during mutation testing.

For example:

{
  "ignorePatterns": ["dist"]
}

This will discover all files in your current working directory, except for files matching the "dist" pattern. Stryker uses .gitignore rules to resolve these patterns.

Stryker always adds ['.git', 'node_modules', '/reports', 'stryker.log', '.stryker-tmp'] when resolving these patterns. If you really want them in your sandbox, you can un-ignore them using a ! prefix in your pattern, for example:

{
  "ignorePatterns": ["!node_modules"]
}

The ignorePatterns is now also the default way files are discovered. Previously, Stryker used git ls-files --others --exclude-standard --cached --exclude .stryker-tmp to discover files by default. This had some limitations:

• ❌ It only worked inside a git repository and you had to have git installed. If not, you got an error and had to use files
• ❌ If a .gitignore'd file is needed to run your tests, you needed to fall back on files.

Specifying files is now deprecated, but still works for the time being. Stryker will rewrite your file patterns internally to ignore patterns.

Closes #1593
Closes #2739

BREAKING CHANGE: Stryker will no longer use a git command to determine which files belong to your project. Instead, it will rely on sane defaults. You can change this behavior by defining ignorePatterns.

BREAKING CHANGE: The files configuration option is deprecated and will be removed in a future release. Please use ignorePatterns instead.

This:

{
  "files": ["foo.js"]
}

Is equivalent to:

{
  "ignorePatterns": ["**", "!foo.js"]
}

[nicojs]

@stryker-mutator/stryker-js-and-friends-maintainers What do you think about this? A couple of thoughts:

• I've decided to not go with a .strykerignore file in the end. It would take us a lot of time and code to maintain, which I think isn't really worth it for this niche feature (who is going to override ignorePatterns anyway? 🤷‍♂️)
• I've chosen the name ignorePatterns, which is in line with how eslint calls it, but this could potentially be confusing, since users might expect these patterns to be ignored for mutating... ?
• Should we deprecate or even drop support for "files"? I don't see a reason for users to really use a files array. However, since this was the only way to include non-gitignored files in the past, it might be a bit harsh to out-right deprecate or even remove it.

[nicojs]

Maybe we should rename it to ignoreFiles, so it's more in line with files itself. However, you might think you can specify a .strykerignore or .gitignore file there 🤷‍♂️

[nicojs]

Ok, I think I know what I want to do.

I think I'll deprecate files. If a user defines files, I'll log a warning and rewrite them to ignorePatterns rules:

{  
  "files": [ "src/**/*.ts", "dist/**/*.js"]
}

becomes

{
  "ignorePatterns": ["**", "!src/**/*ts", "!dist/**/*.js"]
}

[simondel]

Changing

{  
  "files": [ "src/**/*.ts", "dist/**/*.js"]
}

into

{
  "ignorePatterns": ["**", "!src/**/*ts", "!dist/**/*.js"]
}

will work, but removing the ignorePatterns all together may also work. Should we let the user know that it might be smart to try running without the suggested change?

[simondel]

Perhaps we should also add a coverage folder to this example

[nicojs]

Yeah, good one, I'll replace dist-test with coverage

[simondel]

Why do you specify reports and stryker.log with a / at the front, but not for other files/folders?

[nicojs]

Because I know for a fact that Stryker places them at the root of your project. For example. I would like the src/reports directory that someone might have to be included. Starting with a / means to only match when it exists in the root of the cwd.

[simondel]

Shouldn't this still be in the schema, but deprecated?

[nicojs]

As explained during the community meeting, I don't want people to use it. The rewrite to ignorePatterns is being done before the options are validated. This is in line with other deprecated options.

[simondel]

Was the ^ intentional here? Or did you mean ~?

[nicojs]

Wow, not using it. Will remove 😅

[simondel]

This is quite unreadable as you're combining a lot of matches. It might be more readable if the sets are more on one line (for example rule.negate && (rule.match(/${entryPath}, true) || rule.match(entryPath, true))

It might also be smart to place the checks in separate variables so you can actually name what's going on

[nicojs]

Since we're using prettier I can't play around with the formatting. Separate variables would work, but it would technically cost performance since all matches would always be done (instead of stopping at the first failing match).

I've added a third matchesXxx helper function:

const matchesDirectoryPartially = (entryPath: string, rule: IMinimatch) => {
      // @ts-expect-error Missing overload in type definitions. See https://github.com/isaacs/minimatch/issues/134
      return rule.match(`/${entryPath}`, true) || rule.match(entryPath, true);
    };

This helps a lot I think.

[nicojs]

I've added a remark about completely removing "files":

DEPRECATED. Use of "files" is deprecated, please use "ignorePatterns" instead (or remove "files" altogether will probably work as well). For now, rewriting them as ["","!src//*.js","src/index.js"]. See https://stryker-mutator.io/docs/stryker-js/configuration/#ignorepatterns-string

[simondel]

LGTM!