Unit testing framework for Jsonnet
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Jsonnetunit is a unit test framework for Jsonnet.




local test = import "path/to/jsonnetunit/test.jsonnet";

    testIdentity: {actual: 1, expect: 1},
    testNeg:      {actual: "YAML", expectNot: "Markup Language"},
    testFact: {
        local fact(n) = if n == 0 then 1 else n * fact(n-1),

        actual: fact(10),
        expect: 3628800
$ jsonnet example_test.jsonnet
    "verify": "Passed 3 test cases"

See std_matchers_test.jsonnet for more examples of other matchers.

How to install

Just git clone.

$ git clone https://github.com/yugui/jsonnetunit.git

Getting started

How to write tests

  1. Create a test file

    Test files must be .jsonnet files which manifestize a result of test.suite function.

    local test = import "path/to/jsonnetunit/test.jsonnet";
  2. Add test cases

    test.suite function takes an object which contains fields prefixed with test. You can add arbitrary number of such fields. test.suite does not directly use any other fields.

    Individual test fields must have at least two fields:

    • actual field: There must be a field named actual. This is the actual value to be verified.
    • expectation field: There must be another field which describes an expectation. This expectation is used to verify the actual value.

          testFoo: {
              actual: std.length('foo'),
              expect: 3,

      The interpretation of the expectation depends on the name of the expectation field. The name expect in the example means that it expects that actual field is equal to the given value.

Simple expectations

Expectation Field Name Description Example
expect value equality {actual: 1+1, expect: 2}
expectNot value inequality {actual: 1+1, expectNot: 3}
expectLt less than {actual: 1+1, expectLt: 3}
expectLe less than or equal to {actual: 1+1, expectLe: 3}
expectGt greater than {actual: 1+1, expectGt: 1}
expectGe greater than or equal to {actual: 1+1, expectGe: 1}


You can describe an abitrary expectation with expectThat. This expectation field takes a unary function or an object.

The function must take an actual value and it must return if the value satisfies your expectation in a boolean value.

  actual: ultimateAnswerToLifeTheUniverseAndEverything(),
  expectThat: function(x) x == 42,

When you pass an object, the object must have two fields actual and result. The first field actual is overridden with the actual value of the test case on evaluation. The second field result must be an boolean which describes whether actual field satisfies your expectation. In this case, you can optionally specifies a custom description of the expectation. This is used as a part of error message when the test case fails.

  actual: ultimateAnswerToLifeTheUniverseAndEverything(),
  expectThat: {
    actual: error "to be overridden",
    result: self.actual == 42,
    description: "Expect %d to be equal to the known value" % self.actual,

Custom expectation matcher

You can also define your own expectation matcher.

  1. Define a binary function which takes actual and expected values. This function must return an object derived from matcher.jsonnet and must have the following three fields.

    • satisfied: (boolean) Returns if self.actual satisfies your expectation
    • positiveMessage: (string) Returns an error message to be returned when self.actual does not satisfies your expectation.
    • negativeMessage: (string) Returns an error message to be returned when self.actual does not satisfies the negation of the expectation.


    local setMatcher(actual, expected) = import "path/to/matcher.jsonnet" {
        satisfied: std.set(actual) == std.set(expected),
        positiveMessage: "Expected " + actual + " to be equal to " + expected + " as a set",
        negativeMessage: "Expected " + actual + " not to be equal to " + expected + " as a set",
  2. Define your expectation field name in the matchers field of the test suite.


        testEq: {
            actual: [6, 7, 2, 3, 7],
            expectSetEq: [2, 3, 6, 7],
        testNe: {
            actual: [6, 7, 2, 3, 7],
            expectSetNe: [1, 2, 3, 4, 5],
    }) {
        matchers+: {
            // Define a new expectation field name "expectSetEq" for set equality
            expectSetEq: {
                matcher: setMatcher,
                expectationType: true,
             // Define a new expectation field name "expectSetNe" for set inequality
            expectSetNe: {
                matcher: setMatcher,
                expectationType: false,


Copyright 2016 Yuki Yugui Sonoda

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at


Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.