wct-istanbul

wct-istanbul

=============================

A fork of web-component-tester-istanbul Istanbul coverage plugin for web-component-tester@^6.6.0 and @t2ym/web-component-tester.

Compatibility Table

	web-component-tester@^6.6.0	@t2ym/web-component-tester@^6.0.2
wct-istanbul	^0.13.0	^0.12.4 - ^0.13.0
polymer-cli	^1.7.0	@t2ym/polymer-cli@^1.3.2
wct-browser-legacy	✅ (*1)	✅ (*1)
browser.js	✅ (*1)	t2ym/web-component-tester#^6.0.2 (*1)
local browsers	✅	✅
Sauce Labs	Small coverage only (*1)	✅ (*1)
import.meta	- (*2)	- (*2)

Notes on Compatibility Table

• (*1) - Sauce Labs Compatibility
  • Squid proxies in Sauce Labs do not pass large socket.io traffic data and thus drop large coverage data
  • wct-istanbul + @t2ym/web-component-tester@^6.0.2 support chopping and combining of large coverage data to pass the Sauce Labs proxies
    • Make sure browser.js from @t2ym/web-component-tester@^6.0.2 or bower t2ym/web-component-tester#^6.0.2 is used
• (*2) - import.meta Support
  • istanbul-lib-instrument@1.10.1 does not support import.meta syntax
  • Workaround: Pre-instrumentation by @babel/cli@^7.0.0-beta.46 with @babel/plugin-syntax-import-meta and babel-plugin-istanbul
    • babel --plugins @babel/plugin-syntax-import-meta,babel-plugin-istanbul target.js
    • Omit targets from include directive in wct.conf.json

Use this plugin to collect and report test coverage (via istanbul) for your project on each test run.

Common Notes

• The same IstanbulJS libraries as nyc v11.0.3 are used since wct-istanbul 0.12.0.
• async/await support with IstanbulJS libraries
• Only global coverage thresholds are effective since wct-istanbul 0.12.0.

Installation

npm install --save-dev wct-istanbul

Notes on @t2ym/web-component-tester

• The module can be installed with @t2ym/web-component-tester

npm install --save-dev @t2ym/web-component-tester
bower install --save-dev t2ym/web-component-tester

• The dedicated fork @t2ym/polymer-cli can be used with the module

npm install -g @t2ym/polymer-cli
# for polymer test
npm install -g wct-istanbul

Basic Usage

Add the following configuration to web-component-tester's config file.

Example

module.exports = {
  plugins: {
    istanbul: {
      dir: "./coverage",
      reporters: ["text-summary", "lcov"],
      include: [
        "**/*.js"
      ],
      exclude: [
        "/polymer/polymer.js",
        "/platform/platform.js"
      ]
    }
  }
}

Options

Below are the available configuration options:

dir

The directory to write coverage reports to.

reporters

An array of istanbul reporters to use.

include

Files to include in instrumentation.

exclude

Files to exclude from instrumentation (this trumps files 'included' with the option above).

Coverage Thresholds

In addition to measuring coverage, this plugin can be used to enforce coverage thresholds. If coverage does not meet the configured thresholds, then the test run will fail, even if all tests passed.

This requires specifying the thresholds option for the plugin

Example

The following configuration will cause the test run to fail if less than 100% of the statements in instrumented files are covered by tests.

module.exports = {
  plugins: {
    istanbul: {
      dir: "./coverage",
      reporters: ["text-summary", "lcov"],
      include: [
        "**/*.js"
      ],
      exclude: [
        "/polymer/polymer.js",
        "/platform/platform.js"
      ],
      thresholds: {
        global: {
          statements: 100
        }
      }
    }
  }
}