tests/testthat/test_greenscale.R

In UBC-MDS/filterizeR: What the Package Does (One Line, Title Case)

# Copyright 2019 Akansha Vashisth
# Licensed under the MIT License (the "License").
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at https://mit-license.org

# March 2019
# This script tests color function of filterizePy package.
# This script tests the color() function
context("Greenscale image")
library(testthat)
library(reader)
library(imager)
library(stringr)
library(png)

input_img <- imager::load.image("test_img/input1.png")
greenscale("test_img/input1.png")
output_img <- imager::load.image(greenscale("test_img/gs_input1.png"))

# input color: image 1
input_img_pixels <- array(c(c(0.9647059, 0.9254902, 0.8470588,
                              0.9254902, 0.8470588, 0.9647059,
                              0.8470588, 0.9647059, 0.9254902),   #R values
                            c(0.9254902, 0.8470588, 0.6901961,
                              0.8470588, 0.6901961, 0.9254902,
                              0.6901961, 0.9254902, 0.8470588),   #G values
                            c(0.8862745, 0.7686275, 0.5333333,
                              0.7686275, 0.5333333, 0.8862745,
                              0.5333333, 0.8862745, 0.7686275)),  #B values
                          dim = c(3,3,3))

exp_img_pixels <- array(c(c(0.5691765, 0.5460392, 0.4997647,
                            0.5460392, 0.4997647, 0.5691765,
                            0.4997647, 0.5691765, 0.5460392),   #R values
                          c(0.9254902, 0.8470588, 0.6901961,
                            0.8470588, 0.6901961, 0.9254902,
                            0.6901961, 0.9254902, 0.8470588),   #G values
                          c(0.8862745, 0.7686275, 0.5333333,
                            0.7686275, 0.5333333, 0.8862745,
                            0.5333333, 0.8862745, 0.7686275)),  #B values
                        dim = c(3,3,3))
test_that("color image converted to greenscale", {
  greenscale("test_img/input1.png")
  output = png::readPNG("test_img/gs_input1.png")
  expect_equal(output, exp_img_pixels, tolerance=1)
})

test_that("Input and output image dimensions match", {
  expect_equal(dim(input_img), dim(output_img))
})

# --------------------------------- Exception handling --------------------------------- #
test_that("Greenscale function throws error for incorrect file path", {
  expect_error(greenscale("file_path.random"))
})

test_that("Input path is not a string", {
  expect_error(greenscale(123, "test_img/gs_input1.png"))
  expect_error(greenscale("test_img/input1.png",
                         c(1,2,3)))
})

test_that("Input path does not exist", {
  expect_error(greenscale("123/greenscale/input1.png",
                         "test_img/greenscale/gs_input1.png"))
})

test_that("Input is not an image", {
  expect_error(greenscale("test_img/greenscale/test.pdf"))
})

test_that("If user specifies additional arguments, it throws an error", {
  expect_error(greenscale("test_img/input1.png",
                         "test_img/gs_input1.png",
                         "abc"))
})