🧪 doctest

doctest is no fuss doctests for Deno. Document your code with JSDoc, provide your @example, and run your tests with deno test.

Usage

1. In your code, document your functions with JSDoc tags, providing @example tags for your examples:

/**
 * A cool function
 *
 * @param {string} name
 * @returns {string} A greeting
 * @example hello("Mr von Neumann")
 * //=> "Hello, Mr von Neumann!"
 */
export function hello(name) {
  return `Hello, ${name}!`;
}

Notes: The function under test must be exported, and it cannot be a default export. Only named exports work. The expected result must be prefixed with the string //=> on the beginning of a new line, after the example code.

2. To execute the test, add a file which is discovered by deno test (e.g. in a tests/ directory), and call doctest with the path to the file, relative to the project root, to be tested:

import { doctest } from "https://deno.land/x/doctest@{VERSION}/mod.js";

/**
 * A test
 */
Deno.test("Tests", doctest("hello.js"));

Where {VERSION} should be substituted with the specific version you want to use.

3. Run deno test and relax. Your code and your examples are tested!

$ deno test

  Tests
    hello.js
      hello
        ✔ hello("Mr von Neumann")
//=> "Hello, Mr von Neumann!"


  1 passing (6ms)

Advanced

doctest can handle Promises (in both examples and expected results), expected Errors (both thrown Errors and rejected Promises), generator functions, and more. Examples are in spec. This also acts as the specification and test suite for doctest.

Running doctest tests

$ deno test -A
running 2 tests from ./test.js
Doctest ...
  mod ... ignored (0ms)
  lib.js ...
    getTests ...
      getTests([{
  name: "Math.max",
  location: {
    filename: "file:///tmp/index.js",
    line: 10,
    col: 0
  },
  jsDoc: {
    tags: [{
      kind: "example",
      doc: "Math.max(1, 3)\n//=> 3"
    }]
  }
}])
//=> [
  {
    functionName: "Math.max",
    location: {
      filename: "file:///tmp/index.js",
      line: 10,
      col: 0
    },
    examples: [{
      test: "Math.max(1, 3)",
      example: "Math.max(1, 3)\n//=> 3",
      expected: "3"
    }]
  }
] ... ok (20ms)
      getTests([{
  kind: "class",
  classDef: {
    methods: [{
      jsDoc: {
        tags: [{
          kind: "example",
          doc: "add(1, 2)\n//=> 3"
        }]
      },
      name: "add",
      location: {
        filename: "file:///tmp/index.js",
        line: 17,
        col: 4711
      }
    }]
  }
}])
//=> [
  {
    functionName: "add",
    location: {
      filename: "file:///tmp/index.js",
      line: 17,
      col: 4711
    },
    examples: [{
      test: "add(1, 2)",
      example: "add(1, 2)\n//=> 3",
      expected: "3"
    }]
  }
] ... ok (12ms)
    getTests ... ok (22ms)
  lib.js ... ok (30ms)
Doctest ... ok (514ms)
Specification ...
  Functions returning a Promise can be tested like a regular function ...
    spec/returns-promise.js ...
      returnsPromise ...
        returnsPromise(17)
//=> 17 ... ok (30ms)
        returnsPromise(17)
//=> Promise.resolve(17) ... ok (22ms)
      returnsPromise ... ok (30ms)
      rejectsPromise ...
        rejectsPromise(17)
//=> throw new Error(17) ... ok (15ms)
        rejectsPromise(17)
//=> Promise.reject(Error(17)) ... ok (9ms)
      rejectsPromise ... ok (18ms)
    spec/returns-promise.js ... ok (37ms)
  Functions returning a Promise can be tested like a regular function ... ok (42ms)
  Functions throwing an Error can be tested by expecting a thrown Error ...
    spec/expect-error.js ...
      throws ...
        throws(4711)
//=> throw new Error(4711) ... ok (26ms)
      throws ... ok (26ms)
    spec/expect-error.js ... ok (31ms)
  Functions throwing an Error can be tested by expecting a thrown Error ... ok (36ms)
  Generator functions can be tested in different ways  ...
    spec/generator-function.js ...
      generateValues ...
        generateValues(["foo", "bar", "baz"]).next()
// Call .next() immediately to check the first value
//=> {
  value: "foo",
  done: false
} ... ok (62ms)
        Array.from(generateValues([42, 17]))
// Consume the iterator into an array, and test that
//=> [42, 17] ... ok (54ms)
        // Assign the iterator to a variable and iterate as many steps as needed
const it = generateValues(["baz", "qux"]);
it.next();
it.next();
it.next();
//=> {
  value: undefined,
  done: true
} ... ok (47ms)
      generateValues ... ok (63ms)
      fibonacci ...
        fibonacci().next().value
//=> 0 ... ok (39ms)
        const f = fibonacci();
f.next();
f.next().value
//=> 1 ... ok (32ms)
        const f = fibonacci();
f.next();
f.next();
f.next().value
//=> 1 ... ok (25ms)
        const f = fibonacci();
[...Array(13)].map(() => f.next().value)
//=> [0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144] ... ok (18ms)
        const f = fibonacci([8, 13]);
[...Array(13)].map(() => f.next().value)
//=> [8, 13, 21, 34, 55, 89, 144, 233, 377, 610, 987, 1597, 2584] ... ok (10ms)
      fibonacci ... ok (39ms)
    spec/generator-function.js ... ok (70ms)
  Generator functions can be tested in different ways  ... ok (76ms)
  Examples without a result are not tested ...
    spec/example-without-result.js ... ok (4ms)
  Examples without a result are not tested ... ok (8ms)
  Sample passing module (@supabase/doctest-js) ...
    spec/sample-passing-module.js ...
      titleize ...
        titleize('wOaH')
//=> 'Woah' ... ok (80ms)
        titleize('w')
//=> 'W' ... ok (70ms)
      titleize ... ok (81ms)
      stringData ...
        stringData(
  'woah'
)
//=> {
  length: 4,
  vowels: 2,
  consonants: 2
} ... ok (62ms)
      stringData ... ok (62ms)
      split ...
        split('why am i doing this?', ' ')
//=> [ 'why', 'am', 'i', 'doing', 'this?' ] ... ok (54ms)
      split ... ok (54ms)
      add ...
        add(1, 2)
//=> 3 ... ok (45ms)
        add(3, 4)
//=> 7 ... ok (38ms)
        add(3, 4)
//=> 7 ... ok (30ms)
      add ... ok (45ms)
      objectToQueryString ...
        objectToQueryString({
 param1: 'hello',
 param2: 'world'
})
//=> 'param1=hello&param2=world' ... ok (23ms)
      objectToQueryString ... ok (23ms)
      convertColumn ...
        convertColumn(
 'age',
 [{name: 'first_name', type: 'text'}, {name: 'age', type: 'int4'}],
 ['Paul', '33'],
 []
)
//=> 33 ... ok (15ms)
        convertColumn(
 'age',
 [{name: 'first_name', type: 'text'}, {name: 'age', type: 'int4'}],
 ['Paul', '33'],
 ['int4']
)
//=> '33' ... ok (10ms)
      convertColumn ... ok (17ms)
    spec/sample-passing-module.js ... ok (90ms)
  Sample passing module (@supabase/doctest-js) ... ok (97ms)
  Sample passing class (@supabase/doctest-js) ...
    spec/sample-passing-class.js ...
      add ...
        new Arithmetic().add(1, 2)
//=> 3 ... ok (39ms)
        const arithmetic = new Arithmetic();
arithmetic.add(1, 9)
//=> 10 ... ok (31ms)
      add ... ok (39ms)
      subtract ...
        new Arithmetic().subtract(10, 2)
//=> 8 ... ok (23ms)
      subtract ... ok (23ms)
      addToThis ...
        new Arithmetic(7).addToThis(3)
//=> 10 ... ok (15ms)
      addToThis ... ok (15ms)
      increaseThis ...
        const arithmetic = new Arithmetic(17);
arithmetic.increaseThis(42);
arithmetic.foo
//=> 59 ... ok (9ms)
      increaseThis ... ok (9ms)
    spec/sample-passing-class.js ... ok (45ms)
  Sample passing class (@supabase/doctest-js) ... ok (52ms)
Specification ... ok (316ms)

ok | 2 passed (59 steps) | 0 failed | 0 ignored (1 step) (850ms)

Development

doctest is under active development. Pull requests are welcome:

1. Fork the repository
2. Clone the project to your own machine
3. Commit changes to a new branch of your fork
4. Push your work (making sure the code is tested!)
5. Submit a pull request

Authors

Linus Thiel linus@yesbabyyes.se.

See also

A similar module for Node.js is @linus/testy.

Thank you

• kiwicopple for providing @supabase/doctest-js, giving rise to adequate frustration to think of a new solution.
• ry as always, for Node.js, Deno and more.

License

ISC License

Copyright 2023 Linus Thiel.

Permission to use, copy, modify, and/or distribute this software for any purpose with or without fee is hereby granted, provided that the above copyright notice and this permission notice appear in all copies.

THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.