README.md

In tmartin1/testr: Unit Tests For R

testr

A Simple unit testing utility for R.

Usage

Import testr and the file to be tested into the spec file. Then use the testr methods in the structure shown below to test the imported function.

Methods

This package exposes the following global methods:

• describe - Initialize a test suite and for grouping similar tests (like a specific method). Takes two parameters: a string to describe what is being tested, and a callback function, which holds the logic to define any variables needed by the tests and define the specific tests themselves, signified by it calls.
• it - Test a specific method, or a specific part of a method. it calls must be inside of a describe callback function. Takes two parameters: a string to describe the specific functionality that is being tested, and a callback function, which holds the logic to setup the specific test parameters and execute the condition tests by calling the expect function.
• expect - Defines a specific condition that needs to be met for the test to pass. expect calls must be inside of an it callback function. You can have more than one expect call inside a single it callback.

Example

# SomeFunctions.R
simpleAdd <- function(a, b) { return(a + b) }
simpleSubtract <- function(a, b) { return(a - b) }
simpleDivide <- function(a, b) {
    if (b == 0) {
        throw('Cannot divide by zero')
    } else {
        return(a/b)
    }
}

# SomeFunctions.spec.R
source(file = "testr.R", local = TRUE)
source(file = "SomeFunctions.R", local = TRUE)

describe('simpleAdd', function() {
    it('adds two values', function() {
        result <- simpleAdd(1, 1)

        expect(result)$toEqual(2)

        expect(simpleAdd(1, 2))$toEqual(3)
        expect(simpleAdd(1, 3))$toEqual(4)
    })

    it('adds two other values', function() {
        result <- simpleAdd(1, 1)

        expect(result)$toEqual(2)
    })

    it('failing test example - subtracts two values', function() {
        result <- simpleAdd(1, 1)

        expect(result)$toEqual(0) # This will cause the test to fail.
        expect(simpleAdd(1, 2))$toEqual(3) # Even though this condition passes, the test will fail b/c the first condition failed.
    })
})

describe('simpleSubtract', function() {
    it('adds two values', function() {
        result <- simpleSubtract(1, 1)

        expect(result)$toEqual(0)
    })

    it('failing test example - adds two values', function() {
        result <- simpleSubtract(1, 1)

        expect(result)$toEqual(2)
    })
})

describe('simpleDivide', function() {
    it('divides two values', function() {
        result <- simpleDivide(1, 1)

        expect(result)$toEqual(1)
    })

    it('throws an error when dividing by zero', function() {
        result <- function() { simpleDivide(1, 0) }

        expect(result)$toThrowAnError()
    })
})

And the output for the above example would be:

[1] "FAILED - simpleAdd"
[1] "     PASSED - adds two values"
[1] "     PASSED - adds two other values"
[1] "     FAILED - failing test example - subtracts two values"
[1] "          expected 2 to equal 0"

[1] "FAILED - simpleSubtract"
[1] "     PASSED - adds two values"
[1] "     FAILED - failing test example - adds two values"
[1] "          expected 0 to equal 2"

[1] "PASSED - simpleDivide"
[1] "     PASSED - divides two values"
[1] "     PASSED - throws an error when dividing by zero"

tmartin1/testr documentation built on Nov. 5, 2019, 10:54 a.m.