juxtaposer

Screen shot capture and comparison tool for testing website changes.

Table of Contents

• Install
  • Global Install
  • Project Install:
• Example project
• Getting Started
• Examples
  • Basic Example
  • advanced example
• Environment translations
• Custom report templates
• Difference Image Types
• Targets
• config file settings
• command line flags
• Flow
• Contribute
• License

Install

Global Install

npm install -g juxtaposer

Project Install:

npm install --save-dev juxtaposer

When installed for a single project, the binary is ./node_module/.bin/juxtaposer

Example project

There is a sample project in the repo. To run the sample app:

• Clone the repo.
• In the example folder, run npm install
• Start the express server: ./bin/www
• Run juxtaposer: ./node_modules/.bin/jux

You should see output very similar to the image below:

If you run juxtaposer with the --report flag, you will see the html report:

Getting Started

Step 1 Make a file in the root of your project called juxtaposer.json with the contents:

juxtaposer.json

{
  "imagesDir": "test_images",
  "substitutions": {
    "prod": {
      "query": "production"
    },
    "dev": {
      "query": "development"
    }
  }
}

Step 2 Make a file in the root of your project called targets.json with the contents:

targets.json

[
  {
    "name": "sample_query.png",
    "url": "https://www.google.com/#q={{query}}"
  }
]

Step 3 Run juxtaposer --report

Step 4 Customize juxtaposer.json and targets.json

Examples

Basic Example

Create your config file:

juxtaposer.json

{
  "imagesDir": "my_images",
  "substitutions": {
    "prod": {
      "subdomain": "www",
      "test_env": ""
    },
    "dev": {
      "subdomain": "testing",
      "test_env": "development."
    }
  }
}

Specify the targets:

targets.json

[
  {
    "name": "photo_homepage.png",
    "url": "http://{{subdomain}}.{{test_env}}example.com/login"
  }
]

When you run the command $ juxtaposer, it will store the url http://www.example.com/login at my_images/baselines/photo_homepage.png and the url http://testing.development.example.com/login at my_images/samples/photo_homepage.png and then the two images are compared.

advanced example

juxtaposer.json

{
  "showReport": true,
  "export": true,
  "targetEnv": "staging",
  "baselineEnv": "production",
  "substitutions": {
    "production": {
      "subdomain": "www"
    },
    "staging": {
      "subdomain": "staging"
    }
  }
}

targets.json

[
  {
    "name": "excluding_two_regions.png",
    "url": "http://{{subdomain}}.example.com",
    "exclude": [ ".stats_section", "#user-info" ]
  },
  {
    "name": "only_the_given_coordinates.png",
    "url": "http://{{subdomain}}.example.com",
    "only": [200, 0, 960, 50]
  },
  {
    "name": "only_the_content_div.png",
    "url": "http://{{subdomain}}.example.com",
    "only": "#content"
  },
  {
    "name": "narrow_view.png",
    "url": "http://{{subdomain}}.example.com",
    "width": 350
  }
]

Environment translations

The substitution values in the config file are used to build the url. It uses the swig template engine to build the urls. Example:

For the url http://{{subdomain}}.{{test_env}}example.com And the substitutions:

"substitutions": {
  "prod": {
    "subdomain": "www",
    "test_env": ""
  },
  "qa": {
    "subdomain": "testing",
    "test_env": "qa."
  },
  "dev": {
    "subdomain": "testing",
    "test_env": "development."
  }
}

Will generate the following domains:

• prod: http://www.example.com
• qa: http://testing.qa.example.com
• dev: http://testing.development.example.com

Note: test_env for both qa and dev in this example have trailing ..

Custom report templates

You can specify your own report template for the html report using the command line flag --report-template or with reportTemplate in the config file. The report template is rendered with the swig template language

The following information will be passed to the template:

{
  "settings": {
    "ranAt": "Tue, 06 May 2014 03:23:28 GMT", // timestamp when the tests ran
    "isBaselineNeeded": false,                // true if the baseline images were captured on this run
    "baselineEnv": "prod",                    // baseline environment
    "targetEnv": "dev",                       // target environment
    "cwd": "/Users/user/code"                 // directory where the test ran
  },
  "tests":  {
    "failed":  [
      {
        "prettyName":     "home page",
        "imageName":      "home_page.png",
        "baselinePath":   "baselines/home_page.png",
        "samplePath":     "samples/home_page.png",
        "diffsPath":      "diffs/home_page.png",
        "compositeImage": "diffs/home_page.comp.png",
        "changesImage":   "diffs/home_page.changes.png",
        "animateImage":   "diffs/home_page.animated.gif"
      },
      {
        //...
      }
    ],
    "skipped": [
      {
        //...
      }
    ]
    "success": [
      {
        "prettyName":   "google homepage",
        "imageName":    "google_homepage.png",
        "baselinePath": "baselines/google_homepage.png",
        "samplePath":   "samples/google_homepage.png",
        "diffsPath":    "diffs/google_homepage.png"
      }
    ]
  }
}

Difference Image Types

Changes View

The changes pixels overlayed on the dimmed version of the baseline image.

Animated View

A gif that switches between the baseline and the sample image.

Composite View

The negative view of the changed pixels.

Diff View

Only the changed pixels on a white background.

Targets

The targets.json file is a list of urls you want to compare. It's a json array of objects. Each target must have a url and a file name. Only the file name needs to be unique.

url

Required

Value: string

The url of the target.

fileName

Required

Value: string

the file name where the screen shot will be stored.

width

Value: integer

The width of the view port for rendering the page.

only

Value: string or array

If the value is a string, it is the css selector used to select the element to be captured. Only the first match will be used for the screenshot.

Uses the method querySelector

If the value is an array, it is the used as the coordinates of the screenshot region. The array must have 4 integer elements elements: [left, top, height width]

exclude

Value: array

An array of css selectors of regions to ignore. Any element that matches any of the css selectors will not be included in compairing the baseline to the sample image.

Warning Any match will be ignored. For example 'div' will ignore all divs on both pages.

Uses the method querySelectorAll

fuzz

Value: integer

Default: 20

The percent of tolerance to allow between two images. A value of 100 will ignore all differences between the two. Only useful if the two pages contain similar images. More Info

config file settings

targetEnv

Value: string

Default: dev

The environment information used to capture the sample images. Please see the substitutions config for more info.

baselineEnv

Value: string

Default: prod

The environment information used to capture the baseline images. Please see the substitutions config for more info

testOnly

Value boolean

Default false

If testOnly is true, it will skip the capturing of images and only compare images in the baselineDir with the images in the samplesDir. This is useful if you want to use your own scripts to capture the images.

showReport

Value boolean

Default false

Auto open the html report when run is completed. Only works on a mac for now.

reportTemplate

Value string

Default N/A

The path relative from the current directory to the html file. The template language used is swig. See the custom template section below.

export

Value boolean

Default false

Create a zip file of the images captured and the html report.

exportPath

Value: string

Default: jux-{{base_env}}-vs-{{sample_env}}-{{date}}.zip

The path and filename relative to the current working directory. The string is evaluated with the swig template language. The following values are passed passed into the path:

• base_env: The name of the base env.
• sample_env: The name of the sample env.
• date: The timestamp of the test run in ISO format

imagesDir

Value: string

Default: test_images

The directory used to store all the images collected. It is resolved relative to the current working directory.

baselinesDir

Value: string

Default: baselines

The folder for the baseline images. It is resolved relative to the imagesDir.

samplesDir

Value: string

Default: samples

The folder for the sample images. It is resolved relative to the imagesDir.

diffsDir

Value: string

Default: diffs

The folder for the diff images. It is resolved relative to the imagesDir.

substitutions

Value: object

Default: an empty object

A key value pair of the environment names and the translation values. See the environment substitutions for more info.

command line flags

--config

Value string

Default: juxtaposer.json

Overrides the path used for loading the config file.

--env

Value: string

Overrides: targetEnv

--base-env

Value: string

Overrides: baselineEnv

--test-only

Value: boolean

Overrides: testOnly

--report

Value: boolean

Overrides: showReport

--report-template

Value: string

Overrides: reportTemplate

--export

Value: boolean

Overrides: export

--export-path

Value: string

Overrides: exportPath

Flow

1. Runs the prechecks
   1. checks to make sure imagemagick is installed
   2. ensures the directory structure is there
   3. checks to see if it needs to capture the baseline images
2. Cleans up the directories
   1. This step can be skipped with the flag --test-only
   2. removes png's and gif's from samplesDir and diffsDir
   3. If baseline images are going to to be captures, it removes png's from the baselinesDir
3. Images are captured
   1. This step can be skipped with the flag --test-only
   2. the baseline images are only captured if the baselinesDir is empty or the flag --base-env=SOME_VALUE is passed
   3. The command populateCmd will be called for both the samples and the baseline images
   4. For each target in the config file, it does the following:
      1. Sets the size of the viewport
      2. Captures the region if one is specified.
      3. Records the dimentions of excluded sections.
      4. Saves the image.
4. Images are tested.
   1. Every png in baselinesDir is compared against the png of the same name in samplesDir
   2. If a baseline images doesn't match the sample image, a series of images diffs are made in diffsDir
   3. If there is not a sample image for a baseline image, that image is marked as skipped
5. Results are recored
   1. The results are displayed in the command line
   2. The html report is generated and saved at the path: {{imagesDir}}/{{reportPath}}
   3. The template for the html report can be changed with the flag --report-template. The path will be relative form the working dir.
   4. If the flag --report is passed, the html report will be opened with the command: open {{imagesDir}}/{{reportPath}}
6. Results are exported in a zip file
   1. This step will only happen if the flag --export is used
   2. The contents of imagesDir will be added to a zip file.
   3. If you want to customize the path, you can specify a path relative to the working dir i.e. --export-path=../archives/{{data}}.zip

Contribute

Please do! Check out our Contributing guide.

License

MIT © 2014-2017 Shutterstock Images, Inc.