Test the NPM package (#972)

* Implement basic test for the NPM package

Just an initial test suite that checks if all promised imports actually 
exist. The testing framework Jest was chosen because of it ease of setup 
and use.

* Implement exhaustive tests of properties for each icon

.travis.yml

@@ -14,6 +14,15 @@ jobs:
         - gem install jekyll
       script:
         - jekyll build
+    - name: "Test package"
+      language: node_js
+      node_js: 8
+      before_script:
+        - npm run prepublishOnly
+      script:
+        - npm run test
+      after_script:
+        - npm run postpublish
 
     - stage: deploy
       name: "NPM Package"

package.json

@@ -18,6 +18,7 @@
   "author": "Simple Icons Collaborators",
   "license": "CC0",
   "devDependencies": {
+    "jest": "^23.5.0",
     "jsonlint2": "^1.7.1",
     "svglint": "^1.0.2"
   },
@@ -25,6 +26,7 @@
     "jsonlint": "jsonlint _data/simple-icons.json -q -V .jsonlintschema",
     "svglint": "svglint icons/* --ci",
     "prepublishOnly": "node scripts/prepublish.js",
-    "postpublish": "rm icons/*.js index.js"
+    "postpublish": "rm icons/*.js index.js",
+    "test": "jest"
   }
 }

tests/icons.test.js

@@ -0,0 +1,24 @@
+const { icons } = require('../_data/simple-icons.json');
+const { titleToFilename } = require('../scripts/utils.js');
+
+icons.forEach(icon => {
+  const filename = titleToFilename(icon.title);
+  const subject = require(`../icons/${filename}.js`);
+
+  test(`${icon.title} has a "title"`, () => {
+    expect(typeof subject.title).toBe('string');
+  });
+
+  test(`${icon.title} has a "hex" value`, () => {
+    expect(typeof subject.hex).toBe('string');
+    expect(subject.hex).toHaveLength(6);
+  });
+
+  test(`${icon.title} has a "source"`, () => {
+    expect(typeof subject.source).toBe('string');
+  });
+
+  test(`${icon.title} has an "svg"`, () => {
+    expect(typeof subject.svg).toBe('string');
+  });
+});

tests/index.test.js

@@ -0,0 +1,23 @@
+const { icons } = require('../_data/simple-icons.json');
+const simpleIcons = require('../index.js');
+
+icons.forEach(icon => {
+  const subject = simpleIcons[icon.title];
+
+  test(`${icon.title} has a "title"`, () => {
+    expect(typeof subject.title).toBe('string');
+  });
+
+  test(`${icon.title} has a "hex" value`, () => {
+    expect(typeof subject.hex).toBe('string');
+    expect(subject.hex).toHaveLength(6);
+  });
+
+  test(`${icon.title} has a "source"`, () => {
+    expect(typeof subject.source).toBe('string');
+  });
+
+  test(`${icon.title} has an "svg"`, () => {
+    expect(typeof subject.svg).toBe('string');
+  });
+});