Handle source map referencing EOL character (#136)

- Detect EOL character for the file. It fixes wrong splitting for source maps generated on Windows environments.
- When checking column boundary verify that the last referenced column is not  EOL.
- Generate source map referencing EOL characters (typescript.ts)
- Fix 'InvalidMappingLine' check. Getting not existing value from array returns `undefined`, not `null`.
- Add test for 'InvalidMappingColumn' error. Generate `invalid-map-column.js` and `invalid-map-line.js`.
- Fix tests for errors
- Use `/` as invalid filename - works on Linux/Windows

src/app-error.ts

@@ -8,6 +8,8 @@ export class AppError extends Error {
 
   constructor(errorContext: ErrorContext, error?: NodeJS.ErrnoException) {
     super();
+    // https://github.com/Microsoft/TypeScript/wiki/Breaking-Changes#extending-built-ins-like-error-array-and-map-may-no-longer-work
+    Object.setPrototypeOf(this, AppError.prototype);
 
     const message = getErrorMessage(errorContext);
 

src/explore.ts

@@ -21,7 +21,7 @@ export async function exploreBundle(
 
   const sourceMapData = await loadSourceMap(code, map);
 
-  const sizes = computeFileSizeMapOptimized(sourceMapData);
+  const sizes = computeFileSizes(sourceMapData);
 
   const files = adjustSourcePaths(sizes.files, options);
 
@@ -85,10 +85,44 @@ async function loadSourceMap(codeFile: File, sourceMapFile?: File): Promise<Sour
   };
 }
 
+function detectEOL(content: string): string {
+  return content.includes('\r\n') ? '\r\n' : '\n';
+}
+
+interface ComputeFileSizesContext {
+  generatedLine: number;
+  generatedColumn: number;
+  line: string;
+  eol: string;
+}
+
+function checkInvalidMappingColumn({
+  generatedLine,
+  generatedColumn,
+  line,
+  eol,
+}: ComputeFileSizesContext): void {
+  const maxColumnIndex = line.length - 1;
+
+  // Columns are 0-based
+  // Ignore case when source map references EOL character (e.g. https://github.com/microsoft/TypeScript/issues/34695)
+  if (generatedColumn > maxColumnIndex && `${line}${eol}`.lastIndexOf(eol) !== generatedColumn) {
+    throw new AppError({
+      code: 'InvalidMappingColumn',
+      generatedLine,
+      generatedColumn,
+      maxColumn: line.length,
+    });
+  }
+}
+
 /** Calculate the number of bytes contributed by each source file */
-function computeFileSizeMapOptimized(sourceMapData: SourceMapData): FileSizes {
+function computeFileSizes(sourceMapData: SourceMapData): FileSizes {
   const { consumer, codeFileContent } = sourceMapData;
-  const lines = codeFileContent.split('\n');
+  const eol = detectEOL(codeFileContent);
+  // Assume only one EOL is used
+  const lines = codeFileContent.split(eol);
+
   const files: FileSizeMap = {};
   let mappedBytes = 0;
 
@@ -97,38 +131,36 @@ function computeFileSizeMapOptimized(sourceMapData: SourceMapData): FileSizes {
   consumer.eachMapping(({ source, generatedLine, generatedColumn, lastGeneratedColumn }) => {
     // Lines are 1-based
     const line = lines[generatedLine - 1];
-    if (line === null) {
+
+    if (line === undefined) {
       throw new AppError({
         code: 'InvalidMappingLine',
-        generatedLine: generatedLine,
+        generatedLine,
         maxLine: lines.length,
       });
     }
 
-    // Columns are 0-based
-    if (generatedColumn >= line.length) {
-      throw new AppError({
-        code: 'InvalidMappingColumn',
-        generatedLine: generatedLine,
-        generatedColumn: generatedColumn,
-        maxColumn: line.length,
-      });
-    }
+    checkInvalidMappingColumn({
+      generatedLine,
+      generatedColumn,
+      line,
+      eol,
+    });
 
     let mappingLength = 0;
     if (lastGeneratedColumn !== null) {
-      if (lastGeneratedColumn >= line.length) {
-        throw new AppError({
-          code: 'InvalidMappingColumn',
-          generatedLine: generatedLine,
-          generatedColumn: lastGeneratedColumn,
-          maxColumn: line.length,
-        });
-      }
+      checkInvalidMappingColumn({
+        generatedLine,
+        generatedColumn: lastGeneratedColumn,
+        line,
+        eol,
+      });
+
       mappingLength = lastGeneratedColumn - generatedColumn + 1;
     } else {
       mappingLength = line.length - generatedColumn;
     }
+
     files[source] = (files[source] || 0) + mappingLength;
     mappedBytes += mappingLength;
   });

tests/api.test.ts

@@ -171,6 +171,11 @@ describe('api', () => {
           bundlesAndFileTokens: { code: 'data/no-map.js' },
           expectedErrorCode: 'NoSourceMap',
         },
+        {
+          name: 'should throw if source map reference column beyond generated last column in line',
+          bundlesAndFileTokens: 'data/invalid-map-column.js',
+          expectedErrorCode: 'InvalidMappingColumn',
+        },
       ];
 
       bundleErrorTests.forEach(function({
@@ -180,12 +185,10 @@ describe('api', () => {
         expectedErrorCode,
       }) {
         it(name, async function() {
-          try {
-            await explore(bundlesAndFileTokens, options);
-          } catch (result) {
+          await expect(explore(bundlesAndFileTokens, options)).to.be.rejected.then(result => {
             const error = result.errors[0];
             expect(error.code).to.equal(expectedErrorCode);
-          }
+          });
         });
       });
 
@@ -198,18 +201,17 @@ describe('api', () => {
         {
           name: 'should throw when cannot save html to file',
           bundlesAndFileTokens: 'data/inline-map.js',
-          options: { output: { format: 'html', filename: '?' } },
+          // `/` supposed to be invalid filename on both Linux and Windows
+          options: { output: { format: 'html', filename: '/' } },
           expectedErrorCode: 'CannotSaveFile',
         },
       ];
 
       appErrorTests.forEach(function({ name, bundlesAndFileTokens, options, expectedErrorCode }) {
         it(name, async function() {
-          try {
-            await explore(bundlesAndFileTokens, options);
-          } catch (error) {
+          await expect(explore(bundlesAndFileTokens, options)).to.be.rejected.then(error => {
             expect(error.code).to.equal(expectedErrorCode);
-          }
+          });
         });
       });
 
@@ -289,6 +291,15 @@ describe('api', () => {
             code: 'data/inline-map.js',
             map: undefined,
           },
+          {
+            code: 'data/invalid-map-column.js',
+            map: undefined,
+          },
+          {
+            code: 'data/invalid-map-line.js',
+            map: undefined,
+          },
+          { code: 'data/map-reference-eol.js', map: undefined },
           {
             code: 'data/no-map.js',
             map: 'data/no-map.js.map',

tests/generate-data/README.md

@@ -0,0 +1,34 @@
+# How to generate
+
+## `invalid-map-column.js`
+
+1. Create `src/invalid-map-column.ts` with content
+```
+console.log('goodbye cruel world');
+console.log('goodbye man');
+```
+2. Run `tsc --inlineSourceMap src/invalid-map-column.ts --outFile ../data/invalid-map-column.js`
+3. Save source map comment from `../data/invalid-map-column.js`
+4. Replace `src/invalid-map-column.ts` content with
+```
+console.log('hello happy world');
+console.log('hello man');
+```
+5. Run `.2` again
+6. Replace source map comment of `../data/invalid-map-column.js` with one from `.3`
+
+## `invalid-map-line.js`
+
+1. Create `src/invalid-map-line.ts` with content
+```
+console.log('hello happy world');
+console.log('hello man');
+```
+2. Run `tsc --inlineSourceMap src/invalid-map-line.ts --outFile ../data/invalid-map-line.js`
+3. Save source map comment from `../data/invalid-map-line.js`
+4. Replace `src/invalid-map-line.ts` content with
+```
+console.log('hello happy world');
+```
+5. Run `.2` again
+6. Replace source map comment of `../data/invalid-map-line.js` with one from `.3`