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A Metalsmith plugin for testing the file objects with Node's assert module.


Install as usual, npm install metalsmith-assert.

Javascript: use(metalsmith-assert(assertions, options))

CLI: You'll lose a few options since it can't support functions.

By default, metalsmith-assert will console.log all AssertionErrors and a summary line. It then calls done(error) with the last AssertionError (if any) or null if all is well.


assertions should be an object containing objects of the following format:

testname : {  // used for the message
  assert:     // which method of assert to call, default -> "ok".  See below.
  actual:     // if a string, the use fileData[actual],
              // special case: if '.', use fileData.contents.toString()
              // else call actual(fileData, filePath, metalsmith)
  expected:   // if a string use it
              // else call expected(fileData, filePath, metalsmith)
              // note: this field is ignored if assert is "ok"
Legal values for assert method are all methods from assert that take "actual" as the first argument.
  • deepEqual(actual, expected, ...)
  • deepStrictEqual(actual, expected, ...)
  • equal(actual, expected, ...)
  • notDeepEqual(actual, expected, ...)
  • notDeepStrictEqual(actual, expected, ...)
  • notEqual(actual, expected, ...)
  • notStrictEqual(actual, expected, ...)
  • ok(actual, ...) (the default method)
  • strictEqual(actual, expected, ...)

Be precise in your spelling and capitalization. You can also use an array of objects, in which case the testname will be the less informative "test N".

Options (all default to null/false)

options.quiet Don't log individual failures, nor the summary of passed/failed.

options.continueBuildOnError Always call done(null) even if there was a failure.

  • If you enable both quiet and continueBuildOnError this module is useless. :-)

options.disable a quick way to turn metalsmith-assert off - it will immediately call done().

options.fileFilter determines which files will be included

  • if missing, include all files.
  • if a string or Regex, only include matching filePaths.
  • if a user-provided-function, include the file when filter(filePath, data, metalsmith) returns true.
    e.g. If you want to use multimatch, pass something like function(filePath) { return multimatch([filePath], ["blogs/**", ...])[0] };


To verify that every file has a title, has a tag === "vacation", and the img is a svg file

      "title exists" : { actual: "title"},
      "tag === vacation" : { assert: "equal", actual: "tag", expected: "vacation" },
      "image is svg" : { actual: function(data) { return /\.svg$/.test(data.img); }
    } ) )

Notes, Todos, and Caveats

Be precise in your spelling and capitalization!