feat(all): handle base64 inline source maps (bcoe#283)

Pulls in Source Map handling logic from Node.js

Author: Benjamin E. Coe

lib/report.js

@@ -185,8 +185,8 @@ class Report {
             if (ext === '.js' || ext === '.ts' || ext === '.mjs') {
               const stat = statSync(fullPath)
               const sourceMap = getSourceMapFromFile(fullPath)
-              if (sourceMap !== undefined) {
-                this.sourceMapCache[`file://${fullPath}`] = { data: JSON.parse(readFileSync(sourceMap).toString()) }
+              if (sourceMap) {
+                this.sourceMapCache[`file://${fullPath}`] = { data: sourceMap }
               }
               emptyReports.push({
                 scriptId: 0,

lib/source-map-from-file.js

@@ -1,24 +1,99 @@
-const { isAbsolute, join, dirname } = require('path')
+/*
+* Copyright Node.js contributors. All rights reserved.
+*
+* Permission is hereby granted, free of charge, to any person obtaining a copy
+* of this software and associated documentation files (the "Software"), to
+* deal in the Software without restriction, including without limitation the
+* rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
+* sell copies of the Software, and to permit persons to whom the Software is
+* furnished to do so, subject to the following conditions:
+*
+* The above copyright notice and this permission notice shall be included in
+* all copies or substantial portions of the Software.
+*
+* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+* IN THE SOFTWARE.
+*/
+// TODO(bcoe): this logic is ported from Node.js' internal source map
+// helpers:
+// https://github.com/nodejs/node/blob/master/lib/internal/source_map/source_map_cache.js
+// we should to upstream and downstream fixes.
+
 const { readFileSync } = require('fs')
+const { fileURLToPath, pathToFileURL } = require('url')
+const util = require('util')
+const debuglog = util.debuglog('c8')
+
 /**
  * Extract the sourcemap url from a source file
  * reference: https://sourcemaps.info/spec.html
  * @param {String} file - compilation target file
  * @returns {String} full path to source map file
  * @private
  */
-function getSourceMapFromFile (file) {
-  const fileBody = readFileSync(file).toString()
-  const sourceMapLineRE = /\/\/[#@] ?sourceMappingURL=([^\s'"]+)\s*$/mg
+function getSourceMapFromFile (filename) {
+  const fileBody = readFileSync(filename).toString()
+  const sourceMapLineRE = /\/[*/]#\s+sourceMappingURL=(?<sourceMappingURL>[^\s]+)/
   const results = fileBody.match(sourceMapLineRE)
   if (results !== null) {
-    const sourceMap = results[results.length - 1].split('=')[1]
-    if (isAbsolute(sourceMap)) {
-      return sourceMap.trim()
-    } else {
-      const base = dirname(file)
-      return join(base, sourceMap).trim()
+    const sourceMappingURL = results.groups.sourceMappingURL
+    const sourceMap = dataFromUrl(pathToFileURL(filename), sourceMappingURL)
+    return sourceMap
+  } else {
+    return null
+  }
+}
+
+function dataFromUrl (sourceURL, sourceMappingURL) {
+  try {
+    const url = new URL(sourceMappingURL)
+    switch (url.protocol) {
+      case 'data:':
+        return sourceMapFromDataUrl(url.pathname)
+      default:
+        return null
+    }
+  } catch (err) {
+    debuglog(err)
+    // If no scheme is present, we assume we are dealing with a file path.
+    const mapURL = new URL(sourceMappingURL, sourceURL).href
+    return sourceMapFromFile(mapURL)
+  }
+}
+
+function sourceMapFromFile (mapURL) {
+  try {
+    const content = readFileSync(fileURLToPath(mapURL), 'utf8')
+    return JSON.parse(content)
+  } catch (err) {
+    debuglog(err)
+    return null
+  }
+}
+
+// data:[<mediatype>][;base64],<data> see:
+// https://tools.ietf.org/html/rfc2397#section-2
+function sourceMapFromDataUrl (url) {
+  const { 0: format, 1: data } = url.split(',')
+  const splitFormat = format.split(';')
+  const contentType = splitFormat[0]
+  const base64 = splitFormat[splitFormat.length - 1] === 'base64'
+  if (contentType === 'application/json') {
+    const decodedData = base64 ? Buffer.from(data, 'base64').toString('utf8') : data
+    try {
+      return JSON.parse(decodedData)
+    } catch (err) {
+      debuglog(err)
+      return null
     }
+  } else {
+    debuglog(`unexpected content-type ${contentType}`)
+    return null
   }
 }
 

test/fixtures/source-maps/inline.js

@@ -139,24 +139,24 @@ hey
 --------------------------|---------|----------|---------|---------|--------------------------------
 File                      | % Stmts | % Branch | % Funcs | % Lines | Uncovered Line #s              
 --------------------------|---------|----------|---------|---------|--------------------------------
-All files                 |   75.76 |    58.23 |   66.67 |   75.76 |                                
+All files                 |   72.64 |    58.23 |   61.11 |   72.64 |                                
  bin                      |   78.85 |       60 |   66.67 |   78.85 |                                
   c8.js                   |   78.85 |       60 |   66.67 |   78.85 | 22,27-29,32-33,41-43,50-51     
- lib                      |   80.75 |    51.85 |   83.33 |   80.75 |                                
+ lib                      |   75.95 |    51.85 |   71.43 |   75.95 |                                
   is-cjs-esm-bridge.js    |      90 |       25 |     100 |      90 | 9                              
   parse-args.js           |   96.13 |    45.45 |     100 |   96.13 | 109-110,118-119,132-133        
   report.js               |   75.35 |    58.82 |   83.33 |   75.35 | ...208,238-239,266-267,273-275 
-  source-map-from-file.js |      44 |      100 |       0 |      44 | 10-23                          
+  source-map-from-file.js |      45 |      100 |       0 |      45 | 39-50,52-67,69-77,81-98        
  lib/commands             |   44.44 |       75 |   16.67 |   44.44 |                                
   check-coverage.js       |   21.31 |      100 |       0 |   21.31 | 9-11,14-27,30-44,46-61         
   report.js               |    93.1 |    71.43 |      50 |    93.1 | 9-10                           
  test/fixtures            |   83.33 |    85.71 |   66.67 |   83.33 |                                
   async.js                |     100 |      100 |     100 |     100 |                                
   normal.js               |      75 |    66.67 |   33.33 |      75 | 14-16,18-20                    
 --------------------------|---------|----------|---------|---------|--------------------------------
-,ERROR: Coverage for lines (75.76%) does not meet global threshold (101%)
+,ERROR: Coverage for lines (72.64%) does not meet global threshold (101%)
 ERROR: Coverage for branches (58.23%) does not meet global threshold (82%)
-ERROR: Coverage for statements (75.76%) does not meet global threshold (95%)
+ERROR: Coverage for statements (72.64%) does not meet global threshold (95%)
 "
 `;
 
@@ -177,8 +177,8 @@ ERROR: Coverage for branches (45.45%) does not meet threshold (82%) for lib/pars
 ERROR: Coverage for lines (75.35%) does not meet threshold (101%) for lib/report.js
 ERROR: Coverage for branches (58.82%) does not meet threshold (82%) for lib/report.js
 ERROR: Coverage for statements (75.35%) does not meet threshold (95%) for lib/report.js
-ERROR: Coverage for lines (44%) does not meet threshold (101%) for lib/source-map-from-file.js
-ERROR: Coverage for statements (44%) does not meet threshold (95%) for lib/source-map-from-file.js
+ERROR: Coverage for lines (45%) does not meet threshold (101%) for lib/source-map-from-file.js
+ERROR: Coverage for statements (45%) does not meet threshold (95%) for lib/source-map-from-file.js
 ERROR: Coverage for lines (100%) does not meet threshold (101%) for test/fixtures/async.js
 ERROR: Coverage for lines (75%) does not meet threshold (101%) for test/fixtures/normal.js
 ERROR: Coverage for branches (66.67%) does not meet threshold (82%) for test/fixtures/normal.js
@@ -189,9 +189,9 @@ ERROR: Coverage for statements (75%) does not meet threshold (95%) for test/fixt
 exports[`c8 check-coverage exits with 0 if coverage within threshold 1`] = `",,"`;
 
 exports[`c8 check-coverage exits with 1 if coverage is below threshold 1`] = `
-",,ERROR: Coverage for lines (75.76%) does not meet global threshold (101%)
+",,ERROR: Coverage for lines (72.64%) does not meet global threshold (101%)
 ERROR: Coverage for branches (58.23%) does not meet global threshold (82%)
-ERROR: Coverage for statements (75.76%) does not meet global threshold (95%)
+ERROR: Coverage for statements (72.64%) does not meet global threshold (95%)
 "
 `;
 
@@ -274,14 +274,14 @@ exports[`c8 report generates report from existing temporary files 1`] = `
 ",--------------------------|---------|----------|---------|---------|--------------------------------
 File                      | % Stmts | % Branch | % Funcs | % Lines | Uncovered Line #s              
 --------------------------|---------|----------|---------|---------|--------------------------------
-All files                 |   75.76 |    58.23 |   66.67 |   75.76 |                                
+All files                 |   72.64 |    58.23 |   61.11 |   72.64 |                                
  bin                      |   78.85 |       60 |   66.67 |   78.85 |                                
   c8.js                   |   78.85 |       60 |   66.67 |   78.85 | 22,27-29,32-33,41-43,50-51     
- lib                      |   80.75 |    51.85 |   83.33 |   80.75 |                                
+ lib                      |   75.95 |    51.85 |   71.43 |   75.95 |                                
   is-cjs-esm-bridge.js    |      90 |       25 |     100 |      90 | 9                              
   parse-args.js           |   96.13 |    45.45 |     100 |   96.13 | 109-110,118-119,132-133        
   report.js               |   75.35 |    58.82 |   83.33 |   75.35 | ...208,238-239,266-267,273-275 
-  source-map-from-file.js |      44 |      100 |       0 |      44 | 10-23                          
+  source-map-from-file.js |      45 |      100 |       0 |      45 | 39-50,52-67,69-77,81-98        
  lib/commands             |   44.44 |       75 |   16.67 |   44.44 |                                
   check-coverage.js       |   21.31 |      100 |       0 |   21.31 | 9-11,14-27,30-44,46-61         
   report.js               |    93.1 |    71.43 |      50 |    93.1 | 9-10                           
@@ -296,24 +296,24 @@ exports[`c8 report supports --check-coverage, when generating reports 1`] = `
 ",--------------------------|---------|----------|---------|---------|--------------------------------
 File                      | % Stmts | % Branch | % Funcs | % Lines | Uncovered Line #s              
 --------------------------|---------|----------|---------|---------|--------------------------------
-All files                 |   75.76 |    58.23 |   66.67 |   75.76 |                                
+All files                 |   72.64 |    58.23 |   61.11 |   72.64 |                                
  bin                      |   78.85 |       60 |   66.67 |   78.85 |                                
   c8.js                   |   78.85 |       60 |   66.67 |   78.85 | 22,27-29,32-33,41-43,50-51     
- lib                      |   80.75 |    51.85 |   83.33 |   80.75 |                                
+ lib                      |   75.95 |    51.85 |   71.43 |   75.95 |                                
   is-cjs-esm-bridge.js    |      90 |       25 |     100 |      90 | 9                              
   parse-args.js           |   96.13 |    45.45 |     100 |   96.13 | 109-110,118-119,132-133        
   report.js               |   75.35 |    58.82 |   83.33 |   75.35 | ...208,238-239,266-267,273-275 
-  source-map-from-file.js |      44 |      100 |       0 |      44 | 10-23                          
+  source-map-from-file.js |      45 |      100 |       0 |      45 | 39-50,52-67,69-77,81-98        
  lib/commands             |   44.44 |       75 |   16.67 |   44.44 |                                
   check-coverage.js       |   21.31 |      100 |       0 |   21.31 | 9-11,14-27,30-44,46-61         
   report.js               |    93.1 |    71.43 |      50 |    93.1 | 9-10                           
  test/fixtures            |   83.33 |    85.71 |   66.67 |   83.33 |                                
   async.js                |     100 |      100 |     100 |     100 |                                
   normal.js               |      75 |    66.67 |   33.33 |      75 | 14-16,18-20                    
 --------------------------|---------|----------|---------|---------|--------------------------------
-,ERROR: Coverage for lines (75.76%) does not meet global threshold (101%)
+,ERROR: Coverage for lines (72.64%) does not meet global threshold (101%)
 ERROR: Coverage for branches (58.23%) does not meet global threshold (82%)
-ERROR: Coverage for statements (75.76%) does not meet global threshold (95%)
+ERROR: Coverage for statements (72.64%) does not meet global threshold (95%)
 "
 `;
 

test/fixtures/source-maps/padded.js.map

@@ -1,14 +1,19 @@
 /* global describe, it */
 const getSourceMapFromFile = require('../lib/source-map-from-file')
 const assert = require('assert')
-const path = require('path')
+const { readFileSync } = require('fs')
 describe('source-map-from-file', () => {
   it('should parse source maps from compiled targets', () => {
     const sourceMap = getSourceMapFromFile('./test/fixtures/all/ts-compiled/main.js')
-    assert.strictEqual(sourceMap, ['test', 'fixtures', 'all', 'ts-compiled', 'main.js.map'].join(path.sep))
+    const expected = JSON.parse(readFileSync(require.resolve('./fixtures/all/ts-compiled/main.js.map'), 'utf8'))
+    assert.deepStrictEqual(sourceMap, expected)
   })
   it('should handle extra whitespace characters', () => {
     const sourceMap = getSourceMapFromFile('./test/fixtures/source-maps/padded.js')
-    assert.strictEqual(sourceMap, ['test', 'fixtures', 'source-maps', 'padded.js.map'].join(path.sep))
+    assert.deepStrictEqual(sourceMap, { version: 3 })
+  })
+  it('should support base64 encoded inline source maps', () => {
+    const sourceMap = getSourceMapFromFile('./test/fixtures/source-maps/inline.js')
+    assert.strictEqual(sourceMap.version, 3)
   })
 })