gtm-datalayer-test

Automated functional testing for Google Tag Manager's Data Layer.

Requirements

To install and run gtm-datalayer-test, you need the following clients / libraries:

• Node.js and npm
• java
• git

Installation

1. Clone the repo with git clone https://github.com/sahava/gtm-datalayer-test.git
2. Run cd gtm-datalayer-test
3. Run npm install to install the dependencies (run as local user, not root)
4. Run npm test to run the example script

Ubuntu 16.04 System Setup

First you need to install Node.js, Java, JRE, git, and build-essentials tools.

1. sudo curl -sL https://deb.nodesource.com/setup_6.x | sudo -E bash -
2. sudo apt-get install -y nodejs
3. sudo apt-get install default-jre git
4. sudo apt-get install -y build-essential

npm test

The npm test script does the following:

1. Starts a simple HTTP server on http://localhost:8080, with the index.html from ./examples.
2. Runs the ./examples/spec/basic_example.js spec against the mock dataLayer in index.html
3. Stops the HTTP server

You can use this script to quickly see how the solution works. Be sure to check both basic_example.js and basic_example.conf.json to understand how the JSON validation works against the actual window.dataLayer object.

Technology

• ajv for validating the configuration JSON
• chai for test assertions
• chai-json-schema for dataLayer JSON schema validation
• chai-subset for dataLayer subset validation
• http-server for testing the solution on localhost
• wdio for wrapping webdriverio
• wdio-mocha-framework for using mocha as the test runner
• wdio-phantomjs-service for using the headless phantomjs browser for tests
• wdio-selenium-standalone-service to simplify Selenium install and start
• wdio-spec-reporter for providing a spec reporter for the tests
• webdriverio for simplifying Selenium test writing and running

How it works

In examples/spec/basic_example.conf.json (see below), you specify both global key-value pairs as well as page-specific configurations. These dataLayer compositions will then be searched on every page (global configuration) as well as on specific pages (page-specific configurations).

You can enforce the schema in basic_example.conf.json using (a very slightly customized) JSON Schema (v4) to describe the objects in window.dataLayer, or you can use a simple subset check.

###JSON Schema You can describe the window.dataLayer objects using JSON Schema. Each object you add to the dataLayer property in the configuration (global or page-specific), will be compiled into its own schema, and this schema will then be checked against the global window.dataLayer structure. There are some slight modifications and hacks to accomodate for the fact that JSON Schema doesn't play that well with Arrays of indeterminate length and composition (such as window.dataLayer often is).

##Subset check You can also simply use a subset check, where you specify each dataLayer object (global or page-specific) with all the keys and values that you expect to find in dataLayer. Note that if you leave a key out, it is considered optional.

To enable the subset check, you will need to add the key-value pair

"@json" : false

to the root of each dataLayer object in the configuration file that you want to validate against.

Example:

{
    "baseUrl" : "https://www.yourdomain.com",
    "dataLayerName" : "dataLayer",
    "dataLayer" : [{
        "@json" : false,
        "someVariable" : "someValue"
    },{
        "someOtherVariable" : {
            "type" : "number",
            "enum" : [1,2,3,4,5]
        }
    }]
}

Here the first object uses the subset check, so it will validate if the global window.dataLayer structure has at least one object with that exact key-value pair ("someVariable" : "someValue") in the root.

The second object uses the modified JSON Schema. It will validate if at least one object in the global window.dataLayer structure has the root key someOtherVariable set to a number in the range of 1-5.

The JSON Schema used for the test configuration must follow the structure described in this README. When you run the tests, the JSON configuration is first validated against its own schema (/lib/validTestConfSchema.json). If validation fails, the test is aborted.

Customize tests

The test is currently contained in /examples/spec/. There are two files:

• basic_example.conf.json - the JSON schema that controls on which pages the test visits and what assertations are run against dataLayer
• basic_example.js - the actual test specification To customize the test, you should modify basic_example.conf.json. Here's what it might look like:

{
    "baseUrl" : "https://www.yourdomain.com",
    "dataLayerName" : "dataLayer",
    "dataLayer" : [{
        "someVariable" : {
            "@rootRequired" : false,
            "type" : "object",
            "properties" : {
                "someDeeperVariable" : {
                    "pattern" : "^deepValue$"
                }
            },
            "required" : ["someDeeperVariable"]
        }
    }],
    "page" : [{
        "path" : "/some-path/",
        "dataLayer" : [{
            "@expect" : "dataLayer to have Enhanced Ecommerce detail object",
            "ecommerce" : {
                "type" : "object",
                "properties" : {
                    "detail" : {
                        "$ref" : "/enhancedEcommerceSchema.json#/definitions/detail"
                    }
                },
                "required" : ["detail"]
            }
        }]
    }]
}

These are all the keys you can currently use:

Property	Type	Description
baseUrl (required)	URI	Base URL for tests, no trailing /.
multipleContainers	Boolean	If true then multiple instances of 'gtm.js' event are permitted in dataLayer.
dataLayerName	String	The name of the global window.dataLayer Array. Make sure this matches what you've configured in the Google Tag Manager container snippet. It defaults to dataLayer.
dataLayer	Array	Global dataLayer configuration. An Array of objects that you expect to find on every page of the site. The objects can be incomplete, as only the named key-value pairs will be searched for.
page	Array	Array of page-specific configurations, where each object corresponds to a page you want to test.
page.path (required)	String	Path of the page you want to test.
page.dataLayer (required)	Array	Array of objects, where each object is a single test run against dataLayer. Each object can have any number of key-value pairs, and only these key-value pairs are searched for (so the objects can be incomplete). The objects should correspond with what you expect to find in dataLayer.
page.dataLayer[].@expect (required)	String	A description of the test. It will be shown in the test reporter output.
(page.)dataLayer[].properties{}.key.@rootRequired	Boolean	If set to false will make this root-level property optional, meaning the test will pass even if the key is not found in the global dataLayer structure.

If you use the JSON Schema option (by default), everything within the dataLayer objects (global and page-specific) must conform to the latest draft of JSON Schema (http://json-schema.org/). The only exceptions are:

• The root level of each dataLayer object is translated directly into properties of respective root level window.dataLayer objects. So instead of specifying the root level dataLayer objects in the configuration as complete JSON Schema objects, just list the properties as keys. Everything else (except for the other exceptions listed below) should be described using the regular JSON Schema specification.
• @expect used in the page-specific configurations to describe the current test for the test reporter. This is required also when using the subset check method.
• @rootRequired used in root-level properties to indicate whether or not they are optional in the global dataLayer structure.

To do

• Add support for navigation (e.g. validate dataLayer after user interactions).
• Improve the configuration to make it easier to use different browser drivers.