From a5690f678647bddf47b9ad39ecf2716b01d99f2f Mon Sep 17 00:00:00 2001
From: Anton Gilgur <agilgur5@gmail.com>
Date: Sat, 30 Nov 2019 12:19:37 -0500
Subject: [PATCH] (test): add initial test harness and one simple test

- ensure that width/height of canvas are trimmed down after drawing a
  purple rectangle in the center

- add test script that uses jest
  - (ci): change CI to run test and test:pub
- configure jest and babel-jest
  - add coverage/ directory to gitignore
  - add babel-jest@23 for Babel 6 support
    - and configure it for .js files due to a jest bug
  - add .babelrc to configure babel-jest
    - can't use .babelrc.js as babel-jest@23 doesn't support it
      - facebook/jest#5324
    - can't use .babelrc for babel-loader (have to duplicate config)
      because babel-loader@6 has some bugs with it and babel-loader@7
      doesn't support webpack@1
      - babel/babel-loader#552

(deps): add jest, babel-jest, and canvas-prebuilt to devDeps
- add canvas-prebuilt@1 to support jest's jsdom v11
  - canvas is used by jsdom for, well, canvas interactions
---
 .babelrc           |  3 +++
 .gitignore         |  1 +
 .travis.yml        |  3 ++-
 jest.config.js     |  6 ++++++
 package.json       |  5 ++++-
 test/index.spec.js | 17 +++++++++++++++++
 6 files changed, 33 insertions(+), 2 deletions(-)
 create mode 100644 .babelrc
 create mode 100644 jest.config.js
 create mode 100644 test/index.spec.js

diff --git a/.babelrc b/.babelrc
new file mode 100644
index 0000000..c13c5f6
--- /dev/null
+++ b/.babelrc
@@ -0,0 +1,3 @@
+{
+  "presets": ["es2015"]
+}
diff --git a/.gitignore b/.gitignore
index df9001d..a7fb6a2 100644
--- a/.gitignore
+++ b/.gitignore
@@ -2,6 +2,7 @@ npm-debug.log*
 node_modules/
 
 build/
+coverage/
 *.tgz
 
 .DS_Store
diff --git a/.travis.yml b/.travis.yml
index 79b0ee6..e837c80 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -2,4 +2,5 @@ language: node_js
 # default is apparently 0.10.48
 node_js: '10.16.0'
 
-script: npm run test:pub
+script: npm test
+after_script: npm run test:pub
diff --git a/jest.config.js b/jest.config.js
new file mode 100644
index 0000000..2267c25
--- /dev/null
+++ b/jest.config.js
@@ -0,0 +1,6 @@
+module.exports = {
+  transform: {
+    // use babel-jest@23 for babel@6 support (https://github.com/facebook/jest/issues/8230#issuecomment-479470547)
+    '\\.js$': require.resolve('babel-jest')
+  }
+}
diff --git a/package.json b/package.json
index 5b82df3..8625e51 100644
--- a/package.json
+++ b/package.json
@@ -29,7 +29,7 @@
     "lint": "standard index.js",
     "build:watch": "webpack --watch -d",
     "build:prod": "webpack -p",
-    "test": "echo \"Error: no test specified\" && exit 1",
+    "test": "jest",
     "test:pub": "npm run build:prod && npm pack",
     "pub": "npm run build:prod && npm publish",
     "changelog": "changelog-maker"
@@ -37,8 +37,11 @@
   "devDependencies": {
     "@agilgur5/changelog-maker": "^3.0.0",
     "babel-core": "^6.0.14",
+    "babel-jest": "^23.6.0",
     "babel-loader": "^6.0.0",
     "babel-preset-es2015": "^6.6.0",
+    "canvas-prebuilt": "^1.6.11",
+    "jest": "^24.9.0",
     "webpack": "^1.12.2"
   }
 }
diff --git a/test/index.spec.js b/test/index.spec.js
new file mode 100644
index 0000000..d0e7582
--- /dev/null
+++ b/test/index.spec.js
@@ -0,0 +1,17 @@
+import trimCanvas from '../index.js'
+
+describe('trimCanvas', () => {
+  it('should trim whitespace', () => {
+    const canvas = document.createElement('canvas')
+    const ctx = canvas.getContext('2d')
+    canvas.width = 1000
+    canvas.height = 1000
+
+    ctx.fillStyle = 'purple'
+    ctx.fillRect(450, 450, 100, 100) // 100x100 purple box in center
+
+    trimCanvas(canvas)
+    expect(canvas.width).toBe(100)
+    expect(canvas.height).toBe(100)
+  })
+})