junit4-parameterized-tests-generator

This project is no longer maintained. Feel free to fork. If it is useful to anyone, let me know!

Script to generate parameterized JUnit-4 tests for test runners that do not support parameterized tests.

Purpose

JUnit-4 has a design flaw where test runners cannot be combined to perform multiple behaviors. For example, JUnit's Parameterized test runner cannot be combined with RobolectricTestRunner, or any other test runner because only one @RunWith annotation is permitted per class.

generateParameterizedTests.js solves this by parsing special comments in the test...

class StepUnitFormatterTests {
    //> Zero(0, "0 steps")
    //> Singular(1, "1 step")
    //> Plural(2, "2 steps")
    //> 999(999, "999 steps")
    //> Thousand(1000, "1,000 steps")
    //> Million(1000000, "1,000,000 steps")
    //> Decimal(3.3, "3 steps")
    //> Negative(-5, "0 steps")
    @ParameterizedTest
    public void testFormat(double numberOfSteps, String expected) {
        Assert.assertEquals(expected, StepUnitFormatter().format(numberOfSteps));
    }
}

...and converting them to individual tests, which get appended to the end of the file like this:

    // DO NOT EDIT BELOW THIS LINE 

    @Test
    public void testFormatZero() {
        testFormat(0, "0 steps")
    }

    @Test
    public void testFormatSingular() {
        testFormat(1, "1 step")
    }
    
    @Test
    public void testFormatPlural() {
        testFormat(2, "2 steps")
    }
    
    // Etc.
}

Installation

1. Copy generateParameterizedTests.js anywhere into your Java project.
2. Copy ParameterizedTest.java into your test source code folder.
3. Update package x.x.x; in ParameterizedTest.java to reflect your project's package structure.

Running

Node must be installed, but npm install is not required. To generate the parameterized tests, run the following:

$ node generateParameterizedTests.js path/to/tests 

Running automatically using Gradle

To avoid having to run the generator manually, a task can be added to your build.gradle file to run the script on preBuild, or any other preferred Gradle task.

task generateParameterizedTests(type: Exec) {
    executable "sh"
    args "-c", "node scripts/generateParameterizedTests.js src/test"
}

preBuild.dependsOn generateParameterizedTests

Attribution

This code is dedicated to the public domain, so no attribution is needed.

This script is based on a similar implementation by Elliot Chance for generating parameterized tests in Swift.