Better StackTraces with filtering and mapping lines

Let us say we have the following stack trace:

    Expected 'bar' to be 'bar1'
    assert@/Users/foo/Workspace/ws/examples/browser-js/test-dist/index.js:11066:27 <- ~/expect/lib/assert.js:29:0
    toBe@/Users/foo/Workspace/ws/examples/browser-js/test-dist/index.js:8037:28 <- ~/expect/lib/Expectation.js:86:0
    /Users/foo/Workspace/ws/examples/browser-js/test-dist/index.js:7909:75 <- test/unit.ts:31:48

First I’d like to filter stack traces from ~/except. Second I want to only see the original source (the part after <-).

I could actually hack the lib/reporter.js at line 92 like this to achieve this result:

    // filter lines
    msg = msg.split('\n').filter(line => !line.match(/~\/expect\/lib/)).join('\n');
    // map lines
    msg = msg.split('\n').map(line => line.match(/\/(.*)<-/) ? line.replace(/\/(.*)<-/, '') : line).join('\n');

The result will be:

    Expected 'bar' to be 'bar1'
     test/unit.ts:31:48

Can I achieve the same behaviour with existing APIs? Or can I add this behaviour with a pull request? I could imagine to add two new fields to the karma config (e.g. mapStackTraceLine/filterStackTraceLine) so everyone can set custom filter/map rules if needed.

[IAMtheIAM]

Thanks!

So I used your example:

      formatError(msg) {

         // Uncommment this to get rid of the entire stack trace, but then you don't know what happened
         // return ''

         // filter out empty lines and node_modules
         if (!msg.trim() || /~/.test(msg)) return ''

         // indent the error beneath the it() message
         let newLine = `  ${msg}`

         if (newLine.includes('webpack:///')) {
            // remove webpack:///
            newLine = newLine.replace('webpack:///', '')

            // remove bundle location, showing only the source location
            newLine = newLine.slice(0, newLine.indexOf(' <- '))
         }

         return `${newLine}\n`
      },

It did clean it up quite a bit, But I’m still getting some weird mode_modules stuff.

Error: No provider for Http! in config/karma.entry.js (line 3185)
      _throwOrNull@node_modules/@angular/core/@angular/core.es5.js:2649:0
      _getByKeyDefault@node_modules/@angular/core/@angular/core.es5.js:2688:0
      _getByKey@node_modules/@angular/core/@angular/core.es5.js:2620:0
      get@node_modules/@angular/core/@angular/core.es5.js:2489:0
      resolveNgModuleDep@node_modules/@angular/core/@angular/core.es5.js:9481:0
      _createClass@node_modules/@angular/core/@angular/core.es5.js:9524:0
      _createProviderInstance$1@node_modules/@angular/core/@angular/core.es5.js:9492:0
      resolveNgModuleDep@node_modules/@angular/core/@angular/core.es5.js:9477:0
      _createClass@node_modules/@angular/core/@angular/core.es5.js:9532:0
      _createProviderInstance$1@node_modules/@angular/core/@angular/core.es5.js:9492:0
      resolveNgModuleDep@node_modules/@angular/core/@angular/core.es5.js:9477:0
      get@node_modules/@angular/core/@angular/core.es5.js:10569:0
      resolveDep@node_modules/@angular/core/@angular/core.es5.js:11072:0
      createClass@node_modules/@angular/core/@angular/core.es5.js:10928:0
      createDirectiveInstance@node_modules/@angular/core/@angular/core.es5.js:10756:21
      createViewNodes@node_modules/@angular/core/@angular/core.es5.js:12197:33
      createRootView@node_modules/@angular/core/@angular/core.es5.js:12092:0
      callWithDebugContext@node_modules/@angular/core/@angular/core.es5.js:13475:25
      debugCreateRootView@node_modules/@angular/core/@angular/core.es5.js:12792:0
      create@node_modules/@angular/core/@angular/core.es5.js:9864:25
      initComponent@node_modules/@angular/core/@angular/core/testing.es5.js:889:0
      invoke@node_modules/zone.js/dist/zone.js:392:0
      onInvoke@node_modules/zone.js/dist/proxy.js:79:0
      invoke@node_modules/zone.js/dist/zone.js:391:0
      onInvoke@node_modules/@angular/core/@angular/core.es5.js:3890:0
      invoke@node_modules/zone.js/dist/zone.js:391:0
      run@node_modules/zone.js/dist/zone.js:142:0
      run@node_modules/@angular/core/@angular/core.es5.js:3821:42
      createComponent@node_modules/@angular/core/@angular/core/testing.es5.js:892:0
      createComponent@node_modules/@angular/core/@angular/core/testing.es5.js:656:0
      src-test/app-components/app/app.spec.ts:52:40
      invoke@node_modules/zone.js/dist/zone.js:392:0
      onInvoke@node_modules/zone.js/dist/proxy.js:79:0
      invoke@node_modules/zone.js/dist/zone.js:391:0
      run@node_modules/zone.js/dist/zone.js:142:0
      node_modules/zone.js/dist/jasmine-patch.js:104:0
      execute@node_modules/zone.js/dist/jasmine-patch.js:132:0
      invokeTask@node_modules/zone.js/dist/zone.js:425:0
      runTask@node_modules/zone.js/dist/zone.js:192:0
      drainMicroTaskQueue@node_modules/zone.js/dist/zone.js:602:0
      run@node_modules/core-js/modules/es6.promise.js:66:0
      node_modules/core-js/modules/es6.promise.js:79:0
      flush@node_modules/core-js/modules/_microtask.js:18:0

So I modified it a little and it works!

      formatError(msg) {

         // Uncommment this to get rid of the entire stack trace, but then you don't know what happened
         // return ''

         // filter out empty lines and node_modules
         if (!msg.trim() || /~/.test(msg) || /node_modules/.test(msg)) return '' // < --- modified this line

         // indent the error beneath the it() message
         let newLine = `  ${msg}`

         if (newLine.includes('webpack:///')) {
            // remove webpack:///
            newLine = newLine.replace('webpack:///', '')

            // remove bundle location, showing only the source location
            newLine = newLine.slice(0, newLine.indexOf(' <- '))
         }

         return `${newLine}\n`
      },

  Error: No provider for Http! in config/karma.entry.js (line 3185)

Thanks a ton @levithomason!

[levithomason]

See my response to your question here, https://github.com/rstacruz/mocha-clean/issues/5#issuecomment-331010426.

The usage changed slightly due to how the stack is passed. Each line is passed one at a time, rather than the whole stack at once.