1 files changed, 150 insertions, 0 deletions
diff --git a/www/wiki/tests/qunit/suites/resources/mediawiki/mediawiki.String.trimByteLength.test.js b/www/wiki/tests/qunit/suites/resources/mediawiki/mediawiki.String.trimByteLength.test.js
new file mode 100644
index 00000000..e2eea94e
--- /dev/null
+++ b/www/wiki/tests/qunit/suites/resources/mediawiki/mediawiki.String.trimByteLength.test.js
@@ -0,0 +1,150 @@
+( function ( $, mw ) {
+	var simpleSample, U_20AC, poop, mbSample,
+		trimByteLength = require( 'mediawiki.String' ).trimByteLength;
+
+	QUnit.module( 'mediawiki.String.trimByteLength', QUnit.newMwEnvironment() );
+
+	// Simple sample (20 chars, 20 bytes)
+	simpleSample = '12345678901234567890';
+
+	// 3 bytes (euro-symbol)
+	U_20AC = '\u20AC';
+
+	// Outside of the BMP (pile of poo emoji)
+	poop = '\uD83D\uDCA9'; // "💩"
+
+	// Multi-byte sample (22 chars, 26 bytes)
+	mbSample = '1234567890' + U_20AC + '1234567890' + U_20AC;
+
+	/**
+	 * Test factory for mw.String#trimByteLength
+	 *
+	 * @param {Object} options
+	 * @param {string} options.description Test name
+	 * @param {string} options.sample Sequence of characters to trim
+	 * @param {string} [options.initial] Previous value of the sequence of characters, if any
+	 * @param {Number} options.limit Length to trim to
+	 * @param {Function} [options.fn] Filter function
+	 * @param {string} options.expected Expected final value
+	 */
+	function byteLimitTest( options ) {
+		var opt = $.extend( {
+			description: '',
+			sample: '',
+			initial: '',
+			limit: 0,
+			fn: function ( a ) { return a; },
+			expected: ''
+		}, options );
+
+		QUnit.test( opt.description, function ( assert ) {
+			var res = trimByteLength( opt.initial, opt.sample, opt.limit, opt.fn );
+
+			assert.equal(
+				res.newVal,
+				opt.expected,
+				'New value matches the expected string'
+			);
+		} );
+	}
+
+	byteLimitTest( {
+		description: 'Limit using the maxlength attribute',
+		limit: 10,
+		sample: simpleSample,
+		expected: '1234567890'
+	} );
+
+	byteLimitTest( {
+		description: 'Limit using a custom value (multibyte)',
+		limit: 14,
+		sample: mbSample,
+		expected: '1234567890' + U_20AC + '1'
+	} );
+
+	byteLimitTest( {
+		description: 'Limit using a custom value (multibyte, outside BMP)',
+		limit: 3,
+		sample: poop,
+		expected: ''
+	} );
+
+	byteLimitTest( {
+		description: 'Limit using a custom value (multibyte) overlapping a byte',
+		limit: 12,
+		sample: mbSample,
+		expected: '1234567890'
+	} );
+
+	byteLimitTest( {
+		description: 'Pass the limit and a callback as input filter',
+		limit: 6,
+		fn: function ( val ) {
+			var title = mw.Title.newFromText( String( val ) );
+			// Return without namespace prefix
+			return title ? title.getMain() : '';
+		},
+		sample: 'User:Sample',
+		expected: 'User:Sample'
+	} );
+
+	byteLimitTest( {
+		description: 'Pass the limit and a callback as input filter',
+		limit: 6,
+		fn: function ( val ) {
+			var title = mw.Title.newFromText( String( val ) );
+			// Return without namespace prefix
+			return title ? title.getMain() : '';
+		},
+		sample: 'User:Example',
+		// The callback alters the value to be used to calculeate
+		// the length. The altered value is "Exampl" which has
+		// a length of 6, the "e" would exceed the limit.
+		expected: 'User:Exampl'
+	} );
+
+	byteLimitTest( {
+		description: 'Input filter that increases the length',
+		limit: 10,
+		fn: function ( text ) {
+			return 'prefix' + text;
+		},
+		sample: simpleSample,
+		// Prefix adds 6 characters, limit is reached after 4
+		expected: '1234'
+	} );
+
+	byteLimitTest( {
+		description: 'Trim from insertion when limit exceeded',
+		limit: 3,
+		initial: 'abc',
+		sample: 'zabc',
+		// Trim from the insertion point (at 0), not the end
+		expected: 'abc'
+	} );
+
+	byteLimitTest( {
+		description: 'Trim from insertion when limit exceeded',
+		limit: 3,
+		initial: 'abc',
+		sample: 'azbc',
+		// Trim from the insertion point (at 1), not the end
+		expected: 'abc'
+	} );
+
+	byteLimitTest( {
+		description: 'Do not cut up false matching substrings in emoji insertions',
+		limit: 12,
+		initial: '\uD83D\uDCA9\uD83D\uDCA9', // "💩💩"
+		sample: '\uD83D\uDCA9\uD83D\uDCB9\uD83E\uDCA9\uD83D\uDCA9', // "💩💹🢩💩"
+		expected: '\uD83D\uDCA9\uD83D\uDCB9\uD83D\uDCA9' // "💩💹💩"
+	} );
+
+	byteLimitTest( {
+		description: 'Unpaired surrogates do not crash',
+		limit: 4,
+		sample: '\uD800\uD800\uDFFF',
+		expected: '\uD800'
+	} );
+
+}( jQuery, mediaWiki ) );