Add tests for getVersionAdded in consistency test

package.json

@@ -40,7 +40,7 @@
   },
   "scripts": {
     "confluence": "node ./node_modules/mdn-confluence/main/generate.es6.js --output-dir=. --bcd-module=./index.js",
-    "mocha": "mocha \"*/**.test.js\"",
+    "mocha": "mocha \"**/*.test.js\"",
     "lint": "node test/lint",
     "fix": "node scripts/fix",
     "mirror": "node scripts/mirror",

test/linter/index.js

@@ -6,7 +6,7 @@ const testRealValues = require('./test-real-values.js');
 const testSchema = require('./test-schema.js');
 const testStyle = require('./test-style.js');
 const testVersions = require('./test-versions.js');
-const testConsistency = require('./test-consistency.js');
+const { testConsistency } = require('./test-consistency.js');
 const testDescriptions = require('./test-descriptions.js');
 
 module.exports = {

test/linter/test-consistency.js

@@ -413,4 +413,4 @@ function testConsistency(filename) {
   return false;
 }
 
-module.exports = testConsistency;
+module.exports = { ConsistencyChecker, testConsistency };

test/linter/test-consistency.test.js

@@ -0,0 +1,52 @@
+const assert = require('assert').strict;
+
+const { ConsistencyChecker } = require('./test-consistency');
+
+const check = new ConsistencyChecker();
+
+describe('ConsistencyChecker.getVersionAdded()', function () {
+  it('returns null for non-real values', () => {
+    assert.equal(check.getVersionAdded({ version_added: null }), null);
+  });
+
+  it('returns null for "preview" values', () => {
+    assert.equal(check.getVersionAdded({ version_added: 'preview' }), null);
+  });
+
+  it('returns the value for real and ranged values', () => {
+    assert.equal(check.getVersionAdded({ version_added: '12' }), '12');
+    assert.equal(check.getVersionAdded({ version_added: '≤11' }), '≤11');
+  });
+
+  it('returns the earliest real value for an array support statement', () => {
+    assert.equal(
+      check.getVersionAdded([
+        { version_added: '≤11' },
+        { version_added: '101' },
+      ]),
+      '≤11',
+    );
+    assert.equal(
+      check.getVersionAdded([
+        { version_added: 'preview' },
+        { version_added: '≤11', flags: [] },
+      ]),
+      null,
+    );
+    assert.equal(
+      check.getVersionAdded([
+        { version_added: true },
+        { version_added: '≤11', flags: [] },
+      ]),
+      null,
+    );
+
+    assert.equal(
+      check.getVersionAdded([
+        { version_added: '87' },
+        { version_added: true, flags: [] },
+      ]),
+      null,
+    );
+  });
+});