Fix some issues with preprocess source maps

src/compiler/preprocess/index.ts

@@ -160,29 +160,6 @@ function decoded_sourcemap_from_generator(generator: any) {
 	return map;
 }
 
-/**
- * Heuristic used to find index of component source inside source map sources.
- */
-function guess_source_index(
-	file_basename: string,
-	decoded_map: DecodedSourceMap
-): number {
-	if (!file_basename) {
-		return decoded_map.sources.findIndex(source => !source);
-	}
-	// different tools produce different sources
-	// (file name, relative path, absolute path)
-	const index = decoded_map.sources.findIndex(source => {
-		const source_basename = source && get_file_basename(source);
-		return source_basename === file_basename;
-	});
-	if (index !== -1) {
-		// also normalize it in on source map
-		decoded_map.sources[index] = file_basename;
-	}
-	return index;
-}
-
 /**
  * Convert a preprocessor output and its leading prefix and trailing suffix into StringWithSourceMap
  */
@@ -214,7 +191,7 @@ function get_replacement(
 			decoded_map = decoded_sourcemap_from_generator(decoded_map);
 		}
 		// offset only segments pointing at original component source
-		const source_index = guess_source_index(file_basename, decoded_map);
+		const source_index = decoded_map.sources.findIndex(source => source === file_basename);
 		sourcemap_add_offset(decoded_map, get_location(offset + prefix.length), source_index);
 	}
 	const processed_with_map = StringWithSourcemap.from_processed(processed.code, decoded_map);

test/sourcemaps/helpers.ts

@@ -1,5 +1,60 @@
+import * as assert from 'assert';
+import { getLocator } from 'locate-character';
 import MagicString, { Bundle } from 'magic-string';
 
+type AssertMappedParameters = {
+	code: string;
+	filename?: string;
+	input: string | ReturnType<typeof getLocator>;
+	input_code?: string;
+	preprocessed: any;
+};
+
+export function assert_mapped(
+	{ code, filename, input, input_code, preprocessed }: AssertMappedParameters
+) {
+	const locate_input = typeof input === 'function' ? input : getLocator(input);
+	if (filename === undefined) filename = 'input.svelte';
+	if (input_code === undefined) input_code = code;	
+
+	const source_loc = locate_input(input_code);
+	assert.notEqual(
+		source_loc,
+		undefined,
+		`failed to locate "${input_code}" in "${filename}"`
+	);
+
+	const transformed_loc = preprocessed.locate_1(code);
+	assert.notEqual(
+		transformed_loc,
+		undefined,
+		`failed to locate "${code}" in transformed "${filename}"`
+	);
+
+	assert.deepEqual(
+		preprocessed.mapConsumer.originalPositionFor(transformed_loc),
+		{
+			source: filename,
+			name: null,
+			line: source_loc.line + 1,
+			column: source_loc.column
+		},
+		`incorrect mappings for "${input_code}" in "${filename}"`
+	);
+}
+
+export function assert_not_located(
+	code: string,
+	locate: ReturnType<typeof getLocator>,
+	filename = 'input.svelte'
+) {
+	assert.equal(
+		locate(code),
+		undefined,
+		`located "${code}" that should be removed from ${filename}`
+	);
+}
+
 export function magic_string_bundle(
 	inputs: Array<{ code: string | MagicString, filename: string }>,
 	filename = 'bundle.js',

test/sourcemaps/samples/external/_config.js

@@ -5,6 +5,7 @@ export const COMMON = ':global(html) { height: 100%; }\n';
 // TODO: removing '\n' breaks test
 // - _actual.svelte.map looks correct
 // - _actual.css.map adds reference to </style> on input.svelte
+// - Most probably caused by bug in current magic-string version (fixed in 0.25.7)
 export const STYLES = '.awesome { color: orange; }\n';
 
 export default {

test/sourcemaps/samples/external/test.js

@@ -1,27 +1,26 @@
-import { getLocator } from 'locate-character';
+import { assert_mapped } from '../../helpers';
 import { COMMON, STYLES } from './_config';
 
-export function test({ assert, input, preprocessed }) {
-
-	const assertMapped = (locateInput, code, filename) => {
-		const sourceLoc = locateInput(code);
-		const transformedLoc = preprocessed.locate_1(code);
-		assert.deepEqual(
-			preprocessed.mapConsumer.originalPositionFor(transformedLoc),
-			{
-				source: filename,
-				name: null,
-				line: sourceLoc.line + 1,
-				column: sourceLoc.column
-			},
-			`failed to locate "${code}"`
-		);
-	};
-
+export function test({ input, preprocessed }) {
 	// Transformed script, main file
-	assertMapped(input.locate, 'Divs ftw!', 'input.svelte');
+	assert_mapped({
+		filename: 'input.svelte',
+		code: 'Divs ftw!',
+		input: input.locate,
+		preprocessed
+	});
 
 	// External files
-	assertMapped(getLocator(COMMON), 'height: 100%;', 'common.scss');
-	assertMapped(getLocator(STYLES), 'color: orange;', 'styles.scss');
+	assert_mapped({
+		filename: 'common.scss',
+		code: 'height: 100%;',
+		input: COMMON,
+		preprocessed
+	});
+	assert_mapped({
+		filename: 'styles.scss',
+		code: 'color: orange;',
+		input: STYLES,
+		preprocessed
+	});
 }

test/sourcemaps/samples/script-and-style/_config.js

@@ -8,14 +8,14 @@ export default {
 	preprocess: [
 		{
 			script: ({ content, filename }) => {
-        const s = new MagicString(content);
-        s.prepend('// This script code is approved\n');
-        return magic_string_preprocessor_result(filename, s);
-      },
-      style: ({ content, filename }) => {
-        const s = new MagicString(content);
-        s.prepend('/* This style code is approved */\n');
-        return magic_string_preprocessor_result(filename, s);
+				const s = new MagicString(content);
+				s.prepend('// This script code is approved\n');
+				return magic_string_preprocessor_result(filename, s);
+			},
+			style: ({ content, filename }) => {
+				const s = new MagicString(content);
+				s.prepend('/* This style code is approved */\n');
+				return magic_string_preprocessor_result(filename, s);
 			}
 		}
 	]

test/sourcemaps/samples/script-and-style/test.js

@@ -1,17 +1,9 @@
-export function test({ assert, input, preprocessed }) {
-	const content = '<h1>Hello world!</h1>';
+import { assert_mapped } from '../../helpers';
 
-	const original = input.locate(content);
-	const transformed = preprocessed.locate_1('<h1>Hello world!</h1>');
-
-	assert.deepEqual(
-		preprocessed.mapConsumer.originalPositionFor(transformed),
-		{
-			source: 'input.svelte',
-			name: null,
-			line: original.line + 1,
-			column: original.column
-		},
-		`failed to locate "${content}"`
-	);
+export function test({ input, preprocessed }) {
+	assert_mapped({
+		code: '<h1>Hello world!</h1>',
+		input: input.locate,
+		preprocessed
+	});
 }

test/sourcemaps/samples/typescript/test.js

@@ -1,30 +1,21 @@
-export function test({ assert, input, preprocessed }) {
-	const assertMapped = (source, transformed) => {
-		const sourceLoc = input.locate(source);
-		const transformedLoc = preprocessed.locate_1(transformed);
-		assert.deepEqual(
-			preprocessed.mapConsumer.originalPositionFor(transformedLoc),
-			{
-				source: 'input.svelte',
-				name: null,
-				line: sourceLoc.line + 1,
-				column: sourceLoc.column
-			},
-			`failed to locate "${transformed}"`
-		);
-	};
-
-	const assertNotMapped = (code) => {
-		const transformedLoc = preprocessed.locate_1(code);
-		assert.strictEqual(transformedLoc, undefined, `failed to remove "${code}"`);
-	};
+import { assert_mapped, assert_not_located } from '../../helpers';
 
+export function test({ input, preprocessed }) {
 	// TS => JS code
-	assertMapped('let count: number = 0;', 'let count = 0;');
+	assert_mapped({
+		code: 'let count = 0;',
+		input_code: 'let count: number = 0;',
+		input: input.locate,
+		preprocessed
+	});
 
 	// Markup, not touched
-	assertMapped('<h1>Hello world!</h1>', '<h1>Hello world!</h1>');
-
+	assert_mapped({
+		code: '<h1>Hello world!</h1>',
+		input: input.locate,
+		preprocessed
+	});
+
 	// TS types, removed
-	assertNotMapped('ITimeoutDestroyer');
+	assert_not_located('ITimeoutDestroyer', preprocessed.locate_1);
 }