karma-jasmine-diff-reporter

Diff and pretty print for failed tests.

Important

The goal of the reporter is to add user-friendly diff highlighting for complex nested structures. Jasmine 2.6 introduced it's own solution, which conflicts with the reporter original intent. When used, reporter will override Jasmine output in order to enchance it.

Install

npm install karma-jasmine-diff-reporter --save-dev

Add reporter to karma config file:

// karma.conf.js
module.exports = function(config) {
  config.set({
    reporters: ['jasmine-diff']
  });
};

You can use it together with another reporters, which tweak the output - just place them after:

reporters: ['jasmine-diff', 'progress']

Some specific reporters might break because of how the output is changed, make sure to place them before:

reporters: ['junit', 'jasmine-diff']

If you have plugins option overriden, make sure to add the reporter in there too (Karma/Loading Plugins)

// karma.conf.js
module.exports = function(config) {
  config.set({
    reporters: ['jasmine-diff'],
    plugins: [
      'karma-jasmine-diff-reporter'
    ]
  });
};

Options

Default options:

// karma.conf.js
module.exports = function(config) {
  config.set({
    jasmineDiffReporter: {
      color: {
        expectedBg: 'bgRed',
        expectedWhitespaceBg: 'bgRed',
        expectedFg: 'white',

        actualBg: 'bgGreen',
        actualWhitespaceBg: 'bgGreen',
        actualFg: 'white',

        warningBg: 'bgYellow',
        warningWhitespaceBg: 'bgYellow',
        warningFg: 'white',

        defaultBg: '',
        defaultFg: ''
      },
      pretty: false,
      multiline: false,
      verbose: true,
      matchers: {}
    }
  });
};

color

• expected* - colors for test expectations
• actual* - colors for actual results
• warning* - values which reporter could not fully diff and they are worth attention
• default* - text of the value which was not highlighted with any of the above colors

You can use any colors that a supported by chalk.

If karma config option colors: false is set, then reporter will ignore any custom colors and display diffs in inverse color of the terminal. (see output example).

To use default terminal color for any of the option just provide an empty string ('') as a value.

pretty

Values in objects and arrays will be indented depending on the nesting level. (see output example)

Disabled by default. To enable:

• pretty: true - 2 spaces for indent level
• pretty: 4 - number of spaces per level
• pretty: '\t' - string per level

multiline

Adds extra newlines to separate Jasmine matcher text from actual values. (see output example)

Disabled by default. To enable:

• multiline: true - 2 newlines before and after the value + 2 spaces of indentation.

• Each option can configured using numbers (number of newlines/spaces) and strings.

  multiline: {
    before: 3,    // 3 newlines
    after: '\n',  // 1 newline
    indent: '  '  // 2 spaces
  }

verbose

If turned off, reduces the output by cutting of some Jasmine-specific syntax.

Enabled by default, which means nothing is cut off. To disable:

• verbose: false - remove all extra Jasmine syntax

• Detailed configuration:

  verbose: {
    object: false
  }

  • object - Jasmine wraps objects - Object({ foo: 42 }), if set to false objects will be displayed without this wrapper - { foo: 42 }.

matchers

By default only Jasmine core matchers are supported. Use this option to add any custom matchers so they could be correctly parsed and highlighted as well.

matchers: {
  toLookTheSameAs: {
    pattern: /Expected ([\S\s]*) to look the same as ([\S\s]*)\./,
    reverse: true,
    format: 'complex'
  }
}

• pattern (required) - pattern to parse a failure message. It must have two capturing groups, which will capture actual and expected values. Suggested regular expression for capturing group is [\S\s]*, which will capture all characters including whitespaces.
• reverse (optional) - if set to true, then the colors, which are used to highlight actual and expected values will be swapped. By default, first capturing group stands for expected value and second - for actual value.
• format (optional) - accepts either a string or a function. String specifies which diff algorithm to use. Available algorithms are:
  • complex (default) - values are deeply parsed and analyzed, diffed parts get highlighted
  • full - highlights the entire values in their appropriate colors
  • multiple - internal option for values which hold multiple arrays
  • passthru - nothing is diffed and highlighted
  • primitive - values are diffed and highlighted as raw strings
  • warning - highlights the entire values in warning colors

Take a look at the definitions of in-built matchers to have a better understaning.

Support

• node.js >= 6
• jasmine >= 2
• karma >= 0.9
• karma-jasmine >= 0.3

Pitfalls

Diffs won't be displayed for a deep nested objects or large arrays, a threshold for these situations is configured in Jasmine. By default it has object nest level MAX_PRETTY_PRINT_DEPTH = 40 and array length MAX_PRETTY_PRINT_ARRAY_LENGTH = 100. It means that if the diff is out of these bounds, then Jasmine will return the same strings for both compared objects and the reporter won't be able to highlight those diffs.

License

MIT