MagicString.js

const assert = require('assert');
const SourceMapConsumer = require('source-map').SourceMapConsumer;
const MagicString = require('./utils/IntegrityCheckingMagicString');

require('source-map-support').install();

describe('MagicString', () => {
	describe('options', () => {
		it('stores source file information', () => {
			const s = new MagicString('abc', {
				filename: 'foo.js'
			});

			assert.equal(s.filename, 'foo.js');
		});
	});

	describe('append', () => {
		it('should append content', () => {
			const s = new MagicString('abcdefghijkl');

			s.append('xyz');
			assert.equal(s.toString(), 'abcdefghijklxyz');

			s.append('xyz');
			assert.equal(s.toString(), 'abcdefghijklxyzxyz');
		});

		it('should return this', () => {
			const s = new MagicString('abcdefghijkl');
			assert.strictEqual(s.append('xyz'), s);
		});

		it('should throw when given non-string content', () => {
			const s = new MagicString('');
			assert.throws(() => s.append([]), TypeError);
		});
	});

	describe('(ap|pre)pend(Left|Right)', () => {
		it('preserves intended order', () => {
			const s = new MagicString('0123456789');

			s.appendLeft(5, 'A');
			s.prependRight(5, 'a');
			s.prependRight(5, 'b');
			s.appendLeft(5, 'B');
			s.appendLeft(5, 'C');
			s.prependRight(5, 'c');

			assert.equal(s.toString(), '01234ABCcba56789');
			assert.equal(s.slice(0, 5), '01234ABC');
			assert.equal(s.slice(5), 'cba56789');

			s.prependLeft(5, '<');
			s.prependLeft(5, '{');
			assert.equal(s.toString(), '01234{<ABCcba56789');

			s.appendRight(5, '>');
			s.appendRight(5, '}');
			assert.equal(s.toString(), '01234{<ABCcba>}56789');

			s.appendLeft(5, '(');
			s.appendLeft(5, '[');
			assert.equal(s.toString(), '01234{<ABC([cba>}56789');

			s.prependRight(5, ')');
			s.prependRight(5, ']');
			assert.equal(s.toString(), '01234{<ABC([])cba>}56789');

			assert.equal(s.slice(0, 5), '01234{<ABC([');
			assert.equal(s.slice(5), '])cba>}56789');
		});

		it('preserves intended order at beginning of string', () => {
			const s = new MagicString('x');

			s.appendLeft(0, '1');
			s.prependLeft(0, '2');
			s.appendLeft(0, '3');
			s.prependLeft(0, '4');

			assert.equal(s.toString(), '4213x');
		});

		it('preserves intended order at end of string', () => {
			const s = new MagicString('x');

			s.appendRight(1, '1');
			s.prependRight(1, '2');
			s.appendRight(1, '3');
			s.prependRight(1, '4');

			assert.equal(s.toString(), 'x4213');
		});
	});

	describe('appendLeft', () => {
		it('should return this', () => {
			const s = new MagicString('abcdefghijkl');
			assert.strictEqual(s.appendLeft(0, 'a'), s);
		});
	});

	describe('appendRight', () => {
		it('should return this', () => {
			const s = new MagicString('abcdefghijkl');
			assert.strictEqual(s.appendRight(0, 'a'), s);
		});
	});

	describe('clone', () => {
		it('should clone a magic string', () => {
			const s = new MagicString('abcdefghijkl');

			s.overwrite(3, 9, 'XYZ');
			const c = s.clone();

			assert.notEqual(s, c);
			assert.equal(c.toString(), 'abcXYZjkl');
		});

		it('should clone filename info', () => {
			const s = new MagicString('abcdefghijkl', { filename: 'foo.js' });
			const c = s.clone();

			assert.equal(c.filename, 'foo.js');
		});

		it('should clone indentExclusionRanges', () => {
			const array = [3, 6];
			const source = new MagicString('abcdefghijkl', {
				filename: 'foo.js',
				indentExclusionRanges: array
			});

			const clone = source.clone();

			assert.notStrictEqual(source.indentExclusionRanges, clone.indentExclusionRanges);
			assert.deepEqual(source.indentExclusionRanges, clone.indentExclusionRanges);
		});

		it('should clone complex indentExclusionRanges', () => {
			const array = [[3, 6], [7, 9]];
			const source = new MagicString('abcdefghijkl', {
				filename: 'foo.js',
				indentExclusionRanges: array
			});

			const clone = source.clone();

			assert.notStrictEqual(source.indentExclusionRanges, clone.indentExclusionRanges);
			assert.deepEqual(source.indentExclusionRanges, clone.indentExclusionRanges);
		});

		it('should clone sourcemapLocations', () => {
			const source = new MagicString('abcdefghijkl', {
				filename: 'foo.js'
			});

			source.addSourcemapLocation(3);

			const clone = source.clone();

			assert.notStrictEqual(source.sourcemapLocations, clone.sourcemapLocations);
			assert.deepEqual(source.sourcemapLocations, clone.sourcemapLocations);
		});

		it('should clone intro and outro', () => {
			const source = new MagicString('defghi');

			source.prepend('abc');
			source.append('jkl');

			const clone = source.clone();

			assert.equal(source.toString(), clone.toString());
		});
	});

	describe('generateMap', () => {
		it('should generate a sourcemap', () => {
			const s = new MagicString('abcdefghijkl').remove(3, 9);

			const map = s.generateMap({
				file: 'output.md',
				source: 'input.md',
				includeContent: true,
				hires: true
			});

			assert.equal(map.version, 3);
			assert.equal(map.file, 'output.md');
			assert.deepEqual(map.sources, ['input.md']);
			assert.deepEqual(map.sourcesContent, ['abcdefghijkl']);
			assert.equal(map.mappings, 'AAAA,CAAC,CAAC,CAAO,CAAC,CAAC');

			assert.equal(map.toString(), '{"version":3,"file":"output.md","sources":["input.md"],"sourcesContent":["abcdefghijkl"],"names":[],"mappings":"AAAA,CAAC,CAAC,CAAO,CAAC,CAAC"}');
			assert.equal(map.toUrl(), 'data:application/json;charset=utf-8;base64,eyJ2ZXJzaW9uIjozLCJmaWxlIjoib3V0cHV0Lm1kIiwic291cmNlcyI6WyJpbnB1dC5tZCJdLCJzb3VyY2VzQ29udGVudCI6WyJhYmNkZWZnaGlqa2wiXSwibmFtZXMiOltdLCJtYXBwaW5ncyI6IkFBQUEsQ0FBQyxDQUFDLENBQU8sQ0FBQyxDQUFDIn0=');

			const smc = new SourceMapConsumer(map);
			let loc;

			loc = smc.originalPositionFor({ line: 1, column: 0 });
			assert.equal(loc.line, 1);
			assert.equal(loc.column, 0);

			loc = smc.originalPositionFor({ line: 1, column: 1 });
			assert.equal(loc.line, 1);
			assert.equal(loc.column, 1);

			loc = smc.originalPositionFor({ line: 1, column: 4 });
			assert.equal(loc.line, 1);
			assert.equal(loc.column, 10);
		});

		it('should generate a correct sourcemap for prepend content when hires = false', () => {
			const s = new MagicString('x\nq');

			s.prepend('y\n');

			const map = s.generateMap({
				includeContent: true,
			});

			assert.equal(map.mappings,';AAAA;AACA');
		});

		it('should generate a correct sourcemap for indented content', () => {
			const s = new MagicString('var answer = 42;\nconsole.log("the answer is %s", answer);');

			s.prepend('\'use strict\';\n\n');
			s.indent('\t').prepend('(function () {\n').append('\n}).call(global);');

			const map = s.generateMap({
				source: 'input.md',
				includeContent: true,
				hires: true
			});

			const smc = new SourceMapConsumer(map);

			const originLoc = smc.originalPositionFor({ line: 5, column: 1 });
			assert.equal(originLoc.line, 2);
			assert.equal(originLoc.column, 0);
		});

		it('should generate a sourcemap using specified locations', () => {
			const s = new MagicString('abcdefghijkl');

			s.addSourcemapLocation(0);
			s.addSourcemapLocation(3);
			s.addSourcemapLocation(10);

			s.remove(6, 9);
			const map = s.generateMap({
				file: 'output.md',
				source: 'input.md',
				includeContent: true
			});

			assert.equal(map.version, 3);
			assert.equal(map.file, 'output.md');
			assert.deepEqual(map.sources, ['input.md']);
			assert.deepEqual(map.sourcesContent, ['abcdefghijkl']);

			assert.equal(map.toString(), '{"version":3,"file":"output.md","sources":["input.md"],"sourcesContent":["abcdefghijkl"],"names":[],"mappings":"AAAA,GAAG,GAAM,CAAC"}');
			assert.equal(map.toUrl(), 'data:application/json;charset=utf-8;base64,eyJ2ZXJzaW9uIjozLCJmaWxlIjoib3V0cHV0Lm1kIiwic291cmNlcyI6WyJpbnB1dC5tZCJdLCJzb3VyY2VzQ29udGVudCI6WyJhYmNkZWZnaGlqa2wiXSwibmFtZXMiOltdLCJtYXBwaW5ncyI6IkFBQUEsR0FBRyxHQUFNLENBQUMifQ==');

			const smc = new SourceMapConsumer(map);
			let loc;

			loc = smc.originalPositionFor({ line: 1, column: 0 });
			assert.equal(loc.line, 1);
			assert.equal(loc.column, 0);

			loc = smc.originalPositionFor({ line: 1, column: 3 });
			assert.equal(loc.line, 1);
			assert.equal(loc.column, 3);

			loc = smc.originalPositionFor({ line: 1, column: 7 });
			assert.equal(loc.line, 1);
			assert.equal(loc.column, 10);
		});

		it('should correctly map inserted content', () => {
			const s = new MagicString('function Foo () {}');

			s.overwrite(9, 12, 'Bar');

			const map = s.generateMap({
				file: 'output.js',
				source: 'input.js',
				includeContent: true
			});

			const smc = new SourceMapConsumer(map);

			const loc = smc.originalPositionFor({ line: 1, column: 9 });
			assert.equal(loc.line, 1);
			assert.equal(loc.column, 9);
		});

		it('should yield consistent results between appendLeft and prependRight', () => {
			const s1 = new MagicString('abcdefghijkl');
			s1.appendLeft(6, 'X');

			const s2 = new MagicString('abcdefghijkl');
			s2.prependRight(6, 'X');

			const m1 = s1.generateMap({ file: 'output', source: 'input', includeContent: true });
			const m2 = s2.generateMap({ file: 'output', source: 'input', includeContent: true });

			assert.deepEqual(m1, m2);
		});

		it('should recover original names', () => {
			const s = new MagicString('function Foo () {}');

			s.overwrite(9, 12, 'Bar', { storeName: true });

			const map = s.generateMap({
				file: 'output.js',
				source: 'input.js',
				includeContent: true
			});

			const smc = new SourceMapConsumer(map);

			const loc = smc.originalPositionFor({ line: 1, column: 9 });
			assert.equal(loc.name, 'Foo');
		});

		it('should generate one segment per replacement', () => {
			const s = new MagicString('var answer = 42');
			s.overwrite(4, 10, 'number', { storeName: true });

			const map = s.generateMap({
				file: 'output.js',
				source: 'input.js',
				includeContent: true
			});

			const smc = new SourceMapConsumer(map);

			let numMappings = 0;
			smc.eachMapping(() => numMappings += 1);

			assert.equal(numMappings, 3); // one at 0, one at the edit, one afterwards
		});

		it('should generate a sourcemap that correctly locates moved content', () => {
			const s = new MagicString('abcdefghijkl');
			s.move(3, 6, 9);

			const result = s.toString();
			const map = s.generateMap({
				file: 'output.js',
				source: 'input.js',
				includeContent: true,
				hires: true
			});

			const smc = new SourceMapConsumer(map);

			'abcdefghijkl'.split('').forEach((letter, i) => {
				const column = result.indexOf(letter);
				const loc = smc.originalPositionFor({ line: 1, column });

				assert.equal(loc.line, 1);
				assert.equal(loc.column, i);
			});
		});

		it('generates a map with trimmed content (#53)', () => {
			const s1 = new MagicString('abcdefghijkl ').trim();
			const map1 = s1.generateMap({
				file: 'output',
				source: 'input',
				includeContent: true,
				hires: true
			});

			const smc1 = new SourceMapConsumer(map1);
			const loc1 = smc1.originalPositionFor({ line: 1, column: 11 });

			assert.equal(loc1.column, 11);

			const s2 = new MagicString(' abcdefghijkl').trim();
			const map2 = s2.generateMap({
				file: 'output',
				source: 'input',
				includeContent: true,
				hires: true
			});

			const smc2 = new SourceMapConsumer(map2);
			const loc2 = smc2.originalPositionFor({ line: 1, column: 1 });

			assert.equal(loc2.column, 2);
		});

		it('skips empty segments at the start', () => {
			const s = new MagicString('abcdefghijkl');
			s.remove(0, 3).remove(3, 6);

			const map = s.generateMap();
			const smc = new SourceMapConsumer(map);
			const loc = smc.originalPositionFor({ line: 1, column: 6 });

			assert.equal(loc.column, 6);
		});

		it('skips indentation at the start', () => {
			const s = new MagicString('abcdefghijkl');
			s.indent('    ');

			const map = s.generateMap();
			assert.equal(map.mappings, 'IAAA');
		});
	});

	describe('getIndentString', () => {
		it('should guess the indent string', () => {
			const s = new MagicString('abc\n  def\nghi');
			assert.equal(s.getIndentString(), '  ');
		});

		it('should return a tab if no lines are indented', () => {
			const s = new MagicString('abc\ndef\nghi');
			assert.equal(s.getIndentString(), '\t');
		});
	});

	describe('indent', () => {
		it('should indent content with a single tab character by default', () => {
			const s = new MagicString('abc\ndef\nghi\njkl');

			s.indent();
			assert.equal(s.toString(), '\tabc\n\tdef\n\tghi\n\tjkl');

			s.indent();
			assert.equal(s.toString(), '\t\tabc\n\t\tdef\n\t\tghi\n\t\tjkl');
		});

		it('should indent content, using existing indentation as a guide', () => {
			const s = new MagicString('abc\n  def\n    ghi\n  jkl');

			s.indent();
			assert.equal(s.toString(), '  abc\n    def\n      ghi\n    jkl');

			s.indent();
			assert.equal(s.toString(), '    abc\n      def\n        ghi\n      jkl');
		});

		it('should disregard single-space indentation when auto-indenting', () => {
			const s = new MagicString('abc\n/**\n *comment\n */');

			s.indent();
			assert.equal(s.toString(), '\tabc\n\t/**\n\t *comment\n\t */');
		});

		it('should indent content using the supplied indent string', () => {
			const s = new MagicString('abc\ndef\nghi\njkl');

			s.indent('  ');
			assert.equal(s.toString(), '  abc\n  def\n  ghi\n  jkl');

			s.indent('>>');
			assert.equal(s.toString(), '>>  abc\n>>  def\n>>  ghi\n>>  jkl');
		});

		it('should indent content using the empty string if specified (i.e. noop)', () => {
			const s = new MagicString('abc\ndef\nghi\njkl');

			s.indent('');
			assert.equal(s.toString(), 'abc\ndef\nghi\njkl');
		});

		it('should prevent excluded characters from being indented', () => {
			const s = new MagicString('abc\ndef\nghi\njkl');

			s.indent('  ', { exclude: [7, 15] });
			assert.equal(s.toString(), '  abc\n  def\nghi\njkl');

			s.indent('>>', { exclude: [7, 15] });
			assert.equal(s.toString(), '>>  abc\n>>  def\nghi\njkl');
		});

		it('should not add characters to empty lines', () => {
			const s = new MagicString('\n\nabc\ndef\n\nghi\njkl');

			s.indent();
			assert.equal(s.toString(), '\n\n\tabc\n\tdef\n\n\tghi\n\tjkl');

			s.indent();
			assert.equal(s.toString(), '\n\n\t\tabc\n\t\tdef\n\n\t\tghi\n\t\tjkl');
		});

		it('should not add characters to empty lines, even on Windows', () => {
			const s = new MagicString('\r\n\r\nabc\r\ndef\r\n\r\nghi\r\njkl');

			s.indent();
			assert.equal(s.toString(), '\r\n\r\n\tabc\r\n\tdef\r\n\r\n\tghi\r\n\tjkl');

			s.indent();
			assert.equal(s.toString(), '\r\n\r\n\t\tabc\r\n\t\tdef\r\n\r\n\t\tghi\r\n\t\tjkl');
		});

		it('should indent content with removals', () => {
			const s = new MagicString('/* remove this line */\nvar foo = 1;');

			s.remove(0, 23);
			s.indent();

			assert.equal(s.toString(), '\tvar foo = 1;');
		});

		it('should not indent patches in the middle of a line', () => {
			const s = new MagicString('class Foo extends Bar {}');

			s.overwrite(18, 21, 'Baz');
			assert.equal(s.toString(), 'class Foo extends Baz {}');

			s.indent();
			assert.equal(s.toString(), '\tclass Foo extends Baz {}');
		});

		it('should return this', () => {
			const s = new MagicString('abcdefghijkl');
			assert.strictEqual(s.indent(), s);
		});

		it('should return this on noop', () => {
			const s = new MagicString('abcdefghijkl');
			assert.strictEqual(s.indent(''), s);
		});
	});

	describe('insert', () => {
		it('is deprecated', () => {
			const s = new MagicString('abcdefghijkl');
			assert.throws(() => s.insert(6, 'X'), /deprecated/);
		});

		// TODO move this into prependRight and appendLeft tests

		// it( 'should insert characters in the correct location', () => {
		// 	const s = new MagicString( 'abcdefghijkl' );
		//
		// 	s.insert( 0, '>>>' );
		// 	s.insert( 6, '***' );
		// 	s.insert( 12, '<<<' );
		//
		// 	assert.equal( s.toString(), '>>>abcdef***ghijkl<<<' );
		// });
		//
		// it( 'should return this', () => {
		// 	const s = new MagicString( 'abcdefghijkl' );
		// 	assert.strictEqual( s.insert( 0, 'a' ), s );
		// });
		//
		// it( 'should insert repeatedly at the same position correctly', () => {
		// 	const s = new MagicString( 'ab' );
		// 	assert.equal( s.insert(1, '1').toString(), 'a1b' );
		// 	assert.equal( s.insert(1, '2').toString(), 'a12b' );
		// });
		//
		// it( 'should insert repeatedly at the beginning correctly', () => {
		// 	const s = new MagicString( 'ab' );
		// 	assert.equal( s.insert(0, '1').toString(), '1ab' );
		// 	assert.equal( s.insert(0, '2').toString(), '12ab' );
		// });
		//
		// it( 'should throw when given non-string content', () => {
		// 	const s = new MagicString( '' );
		// 	assert.throws(
		// 		function () { s.insert( 0, [] ); },
		// 		TypeError
		// 	);
		// });
		//
		// it( 'should allow inserting after removed range', () => {
		// 	const s = new MagicString( 'abcd' );
		// 	s.remove( 1, 2 );
		// 	s.insert( 2, 'z' );
		// 	assert.equal( s.toString(), 'azcd' );
		// });
	});

	describe('move', () => {
		it('moves content from the start', () => {
			const s = new MagicString('abcdefghijkl');
			s.move(0, 3, 6);

			assert.equal(s.toString(), 'defabcghijkl');
		});

		it('moves content to the start', () => {
			const s = new MagicString('abcdefghijkl');
			s.move(3, 6, 0);

			assert.equal(s.toString(), 'defabcghijkl');
		});

		it('moves content from the end', () => {
			const s = new MagicString('abcdefghijkl');
			s.move(9, 12, 6);

			assert.equal(s.toString(), 'abcdefjklghi');
		});

		it('moves content to the end', () => {
			const s = new MagicString('abcdefghijkl');
			s.move(6, 9, 12);

			assert.equal(s.toString(), 'abcdefjklghi');
		});

		it('ignores redundant move', () => {
			const s = new MagicString('abcdefghijkl');
			s.prependRight(9, 'X');
			s.move(9, 12, 6);
			s.appendLeft(12, 'Y');
			s.move(6, 9, 12); // this is redundant – [6,9] is already after [9,12]

			assert.equal(s.toString(), 'abcdefXjklYghi');
		});

		it('moves content to the middle', () => {
			const s = new MagicString('abcdefghijkl');
			s.move(3, 6, 9);

			assert.equal(s.toString(), 'abcghidefjkl');
		});

		it('handles multiple moves of the same snippet', () => {
			const s = new MagicString('abcdefghijkl');

			s.move(0, 3, 6);
			assert.equal(s.toString(), 'defabcghijkl');

			s.move(0, 3, 9);
			assert.equal(s.toString(), 'defghiabcjkl');
		});

		it('handles moves of adjacent snippets', () => {
			const s = new MagicString('abcdefghijkl');

			s.move(0, 2, 6);
			assert.equal(s.toString(), 'cdefabghijkl');

			s.move(2, 4, 6);
			assert.equal(s.toString(), 'efabcdghijkl');
		});

		it('handles moves to same index', () => {
			const s = new MagicString('abcdefghijkl');
			s.move(0, 2, 6).move(3, 5, 6);

			assert.equal(s.toString(), 'cfabdeghijkl');
		});

		it('refuses to move a selection to inside itself', () => {
			const s = new MagicString('abcdefghijkl');

			assert.throws(() => s.move(3, 6, 3), /Cannot move a selection inside itself/);

			assert.throws(() => s.move(3, 6, 4), /Cannot move a selection inside itself/);

			assert.throws(() => s.move(3, 6, 6), /Cannot move a selection inside itself/);
		});

		it('allows edits of moved content', () => {
			const s1 = new MagicString('abcdefghijkl');

			s1.move(3, 6, 9);
			s1.overwrite(3, 6, 'DEF');

			assert.equal(s1.toString(), 'abcghiDEFjkl');

			const s2 = new MagicString('abcdefghijkl');

			s2.move(3, 6, 9);
			s2.overwrite(4, 5, 'E');

			assert.equal(s2.toString(), 'abcghidEfjkl');
		});

		// it( 'move follows inserts', () => {
		// 	const s = new MagicString( 'abcdefghijkl' );
		//
		// 	s.appendLeft( 3, 'X' ).move( 6, 9, 3 );
		// 	assert.equal( s.toString(), 'abcXghidefjkl' );
		// });
		//
		// it( 'inserts follow move', () => {
		// 	const s = new MagicString( 'abcdefghijkl' );
		//
		// 	s.insert( 3, 'X' ).move( 6, 9, 3 ).insert( 3, 'Y' );
		// 	assert.equal( s.toString(), 'abcXghiYdefjkl' );
		// });
		//
		// it( 'discards inserts at end of move by default', () => {
		// 	const s = new MagicString( 'abcdefghijkl' );
		//
		// 	s.insert( 6, 'X' ).move( 3, 6, 9 );
		// 	assert.equal( s.toString(), 'abcXghidefjkl' );
		// });

		it('moves content inserted at end of range', () => {
			const s = new MagicString('abcdefghijkl');

			s.appendLeft(6, 'X').move(3, 6, 9);
			assert.equal(s.toString(), 'abcghidefXjkl');
		});

		it('returns this', () => {
			const s = new MagicString('abcdefghijkl');
			assert.strictEqual(s.move(3, 6, 9), s);
		});
	});

	describe('overwrite', () => {
		it('should replace characters', () => {
			const s = new MagicString('abcdefghijkl');

			s.overwrite(5, 8, 'FGH');
			assert.equal(s.toString(), 'abcdeFGHijkl');
		});

		it('should throw an error if overlapping replacements are attempted', () => {
			const s = new MagicString('abcdefghijkl');

			s.overwrite(7, 11, 'xx');

			assert.throws(() => s.overwrite(8, 12, 'yy'), /Cannot split a chunk that has already been edited/);

			assert.equal(s.toString(), 'abcdefgxxl');

			s.overwrite(6, 12, 'yes');
			assert.equal(s.toString(), 'abcdefyes');
		});

		it('should allow contiguous but non-overlapping replacements', () => {
			const s = new MagicString('abcdefghijkl');

			s.overwrite(3, 6, 'DEF');
			assert.equal(s.toString(), 'abcDEFghijkl');

			s.overwrite(6, 9, 'GHI');
			assert.equal(s.toString(), 'abcDEFGHIjkl');

			s.overwrite(0, 3, 'ABC');
			assert.equal(s.toString(), 'ABCDEFGHIjkl');

			s.overwrite(9, 12, 'JKL');
			assert.equal(s.toString(), 'ABCDEFGHIJKL');
		});

		it('does not replace zero-length inserts at overwrite start location', () => {
			const s = new MagicString('abcdefghijkl');

			s.remove(0, 6);
			s.appendLeft(6, 'DEF');
			s.overwrite(6, 9, 'GHI');
			assert.equal(s.toString(), 'DEFGHIjkl');
		});

		it('replaces zero-length inserts inside overwrite', () => {
			const s = new MagicString('abcdefghijkl');

			s.appendLeft(6, 'XXX');
			s.overwrite(3, 9, 'DEFGHI');
			assert.equal(s.toString(), 'abcDEFGHIjkl');
		});

		it('replaces non-zero-length inserts inside overwrite', () => {
			const s = new MagicString('abcdefghijkl');

			s.overwrite(3, 4, 'XXX');
			s.overwrite(3, 5, 'DE');
			assert.equal(s.toString(), 'abcDEfghijkl');

			s.overwrite(7, 8, 'YYY');
			s.overwrite(6, 8, 'GH');
			assert.equal(s.toString(), 'abcDEfGHijkl');
		});

		it('should return this', () => {
			const s = new MagicString('abcdefghijkl');
			assert.strictEqual(s.overwrite(3, 4, 'D'), s);
		});

		it('should disallow overwriting zero-length ranges', () => {
			const s = new MagicString('x');
			assert.throws(() => s.overwrite(0, 0, 'anything'), /Cannot overwrite a zero-length range – use appendLeft or prependRight instead/);
		});

		it('should throw when given non-string content', () => {
			const s = new MagicString('');
			assert.throws(() => s.overwrite(0, 1, []), TypeError);
		});

		it('replaces interior inserts', () => {
			const s = new MagicString('abcdefghijkl');

			s.appendLeft(1, '&');
			s.prependRight(1, '^');
			s.appendLeft(3, '!');
			s.prependRight(3, '?');
			s.overwrite(1, 3, '...');
			assert.equal(s.toString(), 'a&...?defghijkl');
		});

		it('preserves interior inserts with `contentOnly: true`', () => {
			const s = new MagicString('abcdefghijkl');

			s.appendLeft(1, '&');
			s.prependRight(1, '^');
			s.appendLeft(3, '!');
			s.prependRight(3, '?');
			s.overwrite(1, 3, '...', { contentOnly: true });
			assert.equal(s.toString(), 'a&^...!?defghijkl');
		});

		it('disallows overwriting partially overlapping moved content', () => {
			const s = new MagicString('abcdefghijkl');

			s.move(6, 9, 3);
			assert.throws(() => s.overwrite(5, 7, 'XX'), /Cannot overwrite across a split point/);
		});

		it('disallows overwriting fully surrounding content moved away', () => {
			const s = new MagicString('abcdefghijkl');

			s.move(6, 9, 3);
			assert.throws(() => s.overwrite(4, 11, 'XX'), /Cannot overwrite across a split point/);
		});

		it('disallows overwriting fully surrounding content moved away even if there is another split', () => {
			const s = new MagicString('abcdefghijkl');

			s.move(6, 9, 3);
			s.appendLeft(5, 'foo');
			assert.throws(() => s.overwrite(4, 11, 'XX'), /Cannot overwrite across a split point/);
		});

		it('allows later insertions at the end', () => {
			const s = new MagicString('abcdefg');

			s.appendLeft(4, '(');
			s.overwrite(2, 7, '');
			s.appendLeft(7, 'h');
			assert.equal(s.toString(), 'abh');
		});
	});

	describe('prepend', () => {
		it('should prepend content', () => {
			const s = new MagicString('abcdefghijkl');

			s.prepend('xyz');
			assert.equal(s.toString(), 'xyzabcdefghijkl');

			s.prepend('123');
			assert.equal(s.toString(), '123xyzabcdefghijkl');
		});

		it('should return this', () => {
			const s = new MagicString('abcdefghijkl');
			assert.strictEqual(s.prepend('xyz'), s);
		});
	});

	describe('prependLeft', () => {
		it('should return this', () => {
			const s = new MagicString('abcdefghijkl');
			assert.strictEqual(s.prependLeft(0, 'a'), s);
		});
	});

	describe('prependRight', () => {
		it('should return this', () => {
			const s = new MagicString('abcdefghijkl');
			assert.strictEqual(s.prependRight(0, 'a'), s);
		});
	});

	describe('remove', () => {
		it('should remove characters from the original string', () => {
			const s = new MagicString('abcdefghijkl');

			s.remove(1, 5);
			assert.equal(s.toString(), 'afghijkl');

			s.remove(9, 12);
			assert.equal(s.toString(), 'afghi');
		});

		it('should remove from the start', () => {
			const s = new MagicString('abcdefghijkl');

			s.remove(0, 6);
			assert.equal(s.toString(), 'ghijkl');
		});

		it('should remove from the end', () => {
			const s = new MagicString('abcdefghijkl');

			s.remove(6, 12);
			assert.equal(s.toString(), 'abcdef');
		});

		it('should treat zero-length removals as a no-op', () => {
			const s = new MagicString('abcdefghijkl');

			s.remove(0, 0).remove(6, 6).remove(9, -3);
			assert.equal(s.toString(), 'abcdefghijkl');
		});

		it('should remove overlapping ranges', () => {
			const s1 = new MagicString('abcdefghijkl');

			s1.remove(3, 7).remove(5, 9);
			assert.equal(s1.toString(), 'abcjkl');

			const s2 = new MagicString('abcdefghijkl');

			s2.remove(3, 7).remove(4, 6);
			assert.equal(s2.toString(), 'abchijkl');
		});

		it('should remove overlapping ranges, redux', () => {
			const s = new MagicString('abccde');

			s.remove(2, 3); // c
			s.remove(1, 3); // bc
			assert.equal(s.toString(), 'acde');
		});

		it('should remove modified ranges', () => {
			const s = new MagicString('abcdefghi');

			s.overwrite(3, 6, 'DEF');
			s.remove(2, 7); // cDEFg
			assert.equal(s.slice(1, 8), 'bh');
			assert.equal(s.toString(), 'abhi');
		});

		it('should not remove content inserted after the end of removed range', () => {
			const s = new MagicString('ab.c;');

			s.prependRight(0, '(');
			s.prependRight(4, ')');
			s.remove(2, 4);
			assert.equal(s.toString(), '(ab);');
		});

		it('should remove interior inserts', () => {
			const s = new MagicString('abc;');

			s.appendLeft(1, '[');
			s.prependRight(1, '(');
			s.appendLeft(2, ')');
			s.prependRight(2, ']');
			s.remove(1, 2);
			assert.equal(s.toString(), 'a[]c;');
		});

		it('should provide a useful error when illegal removals are attempted', () => {
			const s = new MagicString('abcdefghijkl');

			s.overwrite(5, 7, 'XX');

			assert.throws(() => s.remove(4, 6), /Cannot split a chunk that has already been edited/);
		});

		it('should return this', () => {
			const s = new MagicString('abcdefghijkl');
			assert.strictEqual(s.remove(3, 4), s);
		});

		it('removes across moved content', () => {
			const s = new MagicString('abcdefghijkl');

			s.move(6, 9, 3);
			s.remove(5, 7);

			assert.equal(s.toString(), 'abchidejkl');
		});
	});

	describe('slice', () => {
		it('should return the generated content between the specified original characters', () => {
			const s = new MagicString('abcdefghijkl');

			assert.equal(s.slice(3, 9), 'defghi');
			s.overwrite(4, 8, 'XX');
			assert.equal(s.slice(3, 9), 'dXXi');
			s.overwrite(2, 10, 'ZZ');
			assert.equal(s.slice(1, 11), 'bZZk');
			assert.equal(s.slice(2, 10), 'ZZ');

			assert.throws(() => s.slice(3, 9));
		});

		it('defaults `end` to the original string length', () => {
			const s = new MagicString('abcdefghijkl');
			assert.equal(s.slice(3), 'defghijkl');
		});

		it('allows negative numbers as arguments', () => {
			const s = new MagicString('abcdefghijkl');
			assert.equal(s.slice(-3), 'jkl');
			assert.equal(s.slice(0, -3), 'abcdefghi');
		});

		it('includes inserted characters, respecting insertion direction', () => {
			const s = new MagicString('abefij');

			s.prependRight(2, 'cd');
			s.appendLeft(4, 'gh');

			assert.equal(s.slice(), 'abcdefghij');
			assert.equal(s.slice(1, 5), 'bcdefghi');
			assert.equal(s.slice(2, 4), 'cdefgh');
			assert.equal(s.slice(3, 4), 'fgh');
			assert.equal(s.slice(0, 2), 'ab');
			assert.equal(s.slice(0, 3), 'abcde');
			assert.equal(s.slice(4, 6), 'ij');
			assert.equal(s.slice(3, 6), 'fghij');
		});

		it('supports characters moved outward', () => {
			const s = new MagicString('abcdEFghIJklmn');

			s.move(4, 6, 2);
			s.move(8, 10, 12);
			assert.equal(s.toString(), 'abEFcdghklIJmn');

			assert.equal(s.slice(1, -1), 'bEFcdghklIJm');
			assert.equal(s.slice(2, -2), 'cdghkl');
			assert.equal(s.slice(3, -3), 'dghk');
			assert.equal(s.slice(4, -4), 'EFcdghklIJ');
			assert.equal(s.slice(5, -5), 'FcdghklI');
			assert.equal(s.slice(6, -6), 'gh');
		});

		it('supports characters moved inward', () => {
			const s = new MagicString('abCDefghijKLmn');

			s.move(2, 4, 6);
			s.move(10, 12, 8);
			assert.equal(s.toString(), 'abefCDghKLijmn');

			assert.equal(s.slice(1, -1), 'befCDghKLijm');
			assert.equal(s.slice(2, -2), 'CDghKL');
			assert.equal(s.slice(3, -3), 'DghK');
			assert.equal(s.slice(4, -4), 'efCDghKLij');
			assert.equal(s.slice(5, -5), 'fCDghKLi');
			assert.equal(s.slice(6, -6), 'gh');
		});

		it('supports characters moved opposing', () => {
			const s = new MagicString('abCDefghIJkl');

			s.move(2, 4, 8);
			s.move(8, 10, 4);
			assert.equal(s.toString(), 'abIJefghCDkl');

			assert.equal(s.slice(1, -1), 'bIJefghCDk');
			assert.equal(s.slice(2, -2), '');
			assert.equal(s.slice(3, -3), '');
			assert.equal(s.slice(-3, 3), 'JefghC');
			assert.equal(s.slice(4, -4), 'efgh');
			assert.equal(s.slice(0, 3), 'abIJefghC');
			assert.equal(s.slice(3), 'Dkl');
			assert.equal(s.slice(0, -3), 'abI');
			assert.equal(s.slice(-3), 'JefghCDkl');
		});

		it('errors if replaced characters are used as slice anchors', () => {
			const s = new MagicString('abcdef');
			s.overwrite(2, 4, 'CD');

			assert.throws(() => s.slice(2, 3), /slice end anchor/);

			assert.throws(() => s.slice(3, 4), /slice start anchor/);

			assert.throws(() => s.slice(3, 5), /slice start anchor/);

			assert.equal(s.slice(1, 5), 'bCDe');
		});

		it('does not error if slice is after removed characters', () => {
			const s = new MagicString('abcdef');

			s.remove(0, 2);

			assert.equal(s.slice(2, 4), 'cd');
		});
	});

	describe('snip', () => {
		it('should return a clone with content outside `start` and `end` removed', () => {
			const s = new MagicString('abcdefghijkl', {
				filename: 'foo.js'
			});

			s.overwrite(6, 9, 'GHI');

			const snippet = s.snip(3, 9);
			assert.equal(snippet.toString(), 'defGHI');
			assert.equal(snippet.filename, 'foo.js');
		});

		it('should snip from the start', () => {
			const s = new MagicString('abcdefghijkl');
			const snippet = s.snip(0, 6);

			assert.equal(snippet.toString(), 'abcdef');
		});

		it('should snip from the end', () => {
			const s = new MagicString('abcdefghijkl');
			const snippet = s.snip(6, 12);

			assert.equal(snippet.toString(), 'ghijkl');
		});

		it('should respect original indices', () => {
			const s = new MagicString('abcdefghijkl');
			const snippet = s.snip(3, 9);

			snippet.overwrite(6, 9, 'GHI');
			assert.equal(snippet.toString(), 'defGHI');
		});
	});

	describe('trim', () => {
		it('should trim original content', () => {
			assert.equal(new MagicString('   abcdefghijkl   ').trim().toString(), 'abcdefghijkl');
			assert.equal(new MagicString('   abcdefghijkl').trim().toString(), 'abcdefghijkl');
			assert.equal(new MagicString('abcdefghijkl   ').trim().toString(), 'abcdefghijkl');
		});

		it('should trim replaced content', () => {
			const s = new MagicString('abcdefghijkl');

			s.overwrite(0, 3, '   ').overwrite(9, 12, '   ').trim();
			assert.equal(s.toString(), 'defghi');
		});

		it('should trim original content before replaced content', () => {
			const s = new MagicString('abc   def');

			s.remove(6, 9);
			assert.equal(s.toString(), 'abc   ');

			s.trim();
			assert.equal(s.toString(), 'abc');
		});

		it('should trim original content after replaced content', () => {
			const s = new MagicString('abc   def');

			s.remove(0, 3);
			assert.equal(s.toString(), '   def');

			s.trim();
			assert.equal(s.toString(), 'def');
		});

		it('should trim original content before and after replaced content', () => {
			const s = new MagicString('abc   def   ghi');

			s.remove(0, 3);
			s.remove(12, 15);
			assert.equal(s.toString(), '   def   ');

			s.trim();
			assert.equal(s.toString(), 'def');
		});

		it('should trim appended/prepended content', () => {
			const s = new MagicString(' abcdefghijkl ');

			s.prepend('  ').append('  ').trim();
			assert.equal(s.toString(), 'abcdefghijkl');
		});

		it('should trim empty string', () => {
			const s = new MagicString('   ');

			assert.equal(s.trim().toString(), '');
		});

		it('should return this', () => {
			const s = new MagicString('  abcdefghijkl  ');
			assert.strictEqual(s.trim(), s);
		});

		it('should support trimming chunks with intro and outro', () => {
			const s = new MagicString('    \n');
			s.appendRight(4, 'test');
			assert.strictEqual(s.trim().toString(), 'test');
		});
	});

	describe('trimLines', () => {
		it('should trim original content', () => {
			const s = new MagicString('\n\n   abcdefghijkl   \n\n');

			s.trimLines();
			assert.equal(s.toString(), '   abcdefghijkl   ');
		});
	});

	describe('isEmpty', () => {
		it('should support isEmpty', () => {
			const s = new MagicString(' abcde   fghijkl ');

			assert.equal(s.isEmpty(), false);

			s.prepend('  ');
			s.append('  ');
			s.remove(1, 6);
			s.remove(9, 15);

			assert.equal(s.isEmpty(), false);

			s.remove(15, 16);

			assert.equal(s.isEmpty(), true);
		});
	});

	describe('length', () => {
		it('should support length', () => {
			const s = new MagicString(' abcde   fghijkl ');

			assert.equal(s.length(), 17);

			s.prepend('  ');
			s.append('  ');
			s.remove(1, 6);
			s.remove(9, 15);

			assert.equal(s.length(), 6);

			s.remove(15, 16);

			assert.equal(s.length(), 5);
		});
	});

	describe('lastLine', () => {
		it('should support lastLine', () => {
			const s = new MagicString(' abcde\nfghijkl ');

			assert.equal(s.lastLine(), 'fghijkl ');

			s.prepend('  ');
			s.append('  ');
			s.remove(1, 6);
			s.remove(9, 15);

			assert.equal(s.lastLine(), 'fg  ');

			s.overwrite(7, 8, '\n');

			assert.equal(s.lastLine(), 'g  ');

			s.append('\n//lastline');

			assert.equal(s.lastLine(), '//lastline');
		});
	});
});