From 88eeffac388b09d6f35272257ec0be38f4beef02 Mon Sep 17 00:00:00 2001
From: Justin Bay <justin.bay@outlook.com>
Date: Fri, 16 Dec 2016 22:33:04 -0500
Subject: [PATCH] Add toggle for picking up inline source maps.

These can take up a lot of memory for large projects, especially if the original source is inlined into the source map.
---
 README.md                         | 34 ++++++++++++++++++++++++++++
 fixtures/has-inline-source-map.js | 12 ++++++++++
 package.json                      |  5 +++++
 src/index.js                      |  6 ++++-
 test/babel-plugin-istanbul.js     | 37 +++++++++++++++++++++++++++++++
 5 files changed, 93 insertions(+), 1 deletion(-)
 create mode 100644 fixtures/has-inline-source-map.js

diff --git a/README.md b/README.md
index 436c937..dbbdf2d 100644
--- a/README.md
+++ b/README.md
@@ -88,6 +88,40 @@ If you don't provide options in your Babel config, the plugin will look for `exc
 
 You can also use [istanbul's ignore hints](https://github.com/gotwarlost/istanbul/blob/master/ignoring-code-for-coverage.md#ignoring-code-for-coverage-purposes) to specify specific lines of code to skip instrumenting.
 
+## Source Maps
+
+By default, this plugin will pick up inline source maps and attach them to the instrumented code such that code coverage can be remapped back to the original source, even for multi-step build processes. This can be memory intensive. Set `useInlineSourceMaps` to prevent this behavior.
+
+```json
+{
+  "env": {
+    "test": {
+      "plugins": [
+        ["istanbul", {
+          "useInlineSourceMaps": false
+        }]
+      ]
+    }
+  }
+}
+```
+
+If you're instrumenting code programatically, you can pass a source map explicitly.
+```js
+import babelPluginIstanbul from 'babel-plugin-istanbul';
+
+function instrument(sourceCode, sourceMap, fileName) {
+  return babel.transform(sourceCode, {
+    filename,
+    plugins: [
+      [babelPluginIstanbul, {
+        inputSourceMap: sourceMap
+      }]
+    ]
+  })
+}
+```
+
 ## Credit where credit is due
 
 The approach used in `babel-plugin-istanbul` was inspired by [Thai Pangsakulyanont](https://github.com/dtinth)'s original library [`babel-plugin-__coverage__`](https://github.com/dtinth/babel-plugin-__coverage__).
diff --git a/fixtures/has-inline-source-map.js b/fixtures/has-inline-source-map.js
new file mode 100644
index 0000000..0b4f480
--- /dev/null
+++ b/fixtures/has-inline-source-map.js
@@ -0,0 +1,12 @@
+"use strict";
+var Say = (function () {
+    function Say() {
+    }
+    Say.prototype.hello = function () {
+        console.log('hello');
+    };
+    return Say;
+}());
+exports.__esModule = true;
+exports["default"] = Say;
+//# sourceMappingURL=data:application/json;base64,eyJ2ZXJzaW9uIjozLCJmaWxlIjoiQ2hlY2tib3gudGVzdC5qcyIsInNvdXJjZVJvb3QiOiIiLCJzb3VyY2VzIjpbIkNoZWNrYm94LnRlc3QudHN4Il0sIm5hbWVzIjpbXSwibWFwcGluZ3MiOiI7QUFBQTtJQUFBO0lBSUEsQ0FBQztJQUhDLG1CQUFLLEdBQUw7UUFDRSxPQUFPLENBQUMsR0FBRyxDQUFDLE9BQU8sQ0FBQyxDQUFDO0lBQ3ZCLENBQUM7SUFDSCxVQUFDO0FBQUQsQ0FBQyxBQUpELElBSUMiLCJzb3VyY2VzQ29udGVudCI6WyJleHBvcnQgZGVmYXVsdCBjbGFzcyBTYXkge1xyXG4gIGhlbGxvKCkge1xyXG4gICAgY29uc29sZS5sb2coJ2hlbGxvJyk7XHJcbiAgfVxyXG59Il19"
\ No newline at end of file
diff --git a/package.json b/package.json
index fa96036..d36b0db 100644
--- a/package.json
+++ b/package.json
@@ -36,6 +36,11 @@
     "prepublish": "npm test && npm run release",
     "version": "standard-version"
   },
+  "standard": {
+    "ignore": [
+      "fixtures/has-inline-source-map.js"
+    ]
+  },
   "repository": {
     "type": "git",
     "url": "git+https://github.com/istanbuljs/babel-plugin-istanbul.git"
diff --git a/src/index.js b/src/index.js
index 7a28594..13b7de8 100644
--- a/src/index.js
+++ b/src/index.js
@@ -43,9 +43,13 @@ function makeVisitor ({types: t}) {
           if (shouldSkip(realPath, this.opts)) {
             return
           }
+          let { inputSourceMap } = this.opts
+          if (this.opts.useInlineSourceMaps !== false) {
+            inputSourceMap = inputSourceMap || this.file.opts.inputSourceMap
+          }
           this.__dv__ = programVisitor(t, realPath, {
             coverageVariable: '__coverage__',
-            inputSourceMap: this.opts.inputSourceMap || this.file.opts.inputSourceMap
+            inputSourceMap
           })
           this.__dv__.enter(path)
         },
diff --git a/test/babel-plugin-istanbul.js b/test/babel-plugin-istanbul.js
index 0a8dbf3..2856150 100644
--- a/test/babel-plugin-istanbul.js
+++ b/test/babel-plugin-istanbul.js
@@ -32,6 +32,43 @@ describe('babel-plugin-istanbul', function () {
     })
   })
 
+  context('source maps', function () {
+    it('should use inline source map', function () {
+      var result = babel.transformFileSync('./fixtures/has-inline-source-map.js', {
+        plugins: [
+          [makeVisitor({types: babel.types}), {
+            include: ['fixtures/has-inline-source-map.js']
+          }]
+        ]
+      })
+      result.code.should.match(/inputSourceMap/)
+    })
+
+    it('should not use inline source map if inputSourceMap is set to false', function () {
+      var result = babel.transformFileSync('./fixtures/has-inline-source-map.js', {
+        plugins: [
+          [makeVisitor({types: babel.types}), {
+            include: ['fixtures/has-inline-source-map.js'],
+            useInlineSourceMaps: false
+          }]
+        ]
+      })
+      result.code.should.not.match(/inputSourceMap/)
+    })
+
+    it('should use provided source map', function () {
+      var result = babel.transformFileSync('./fixtures/has-inline-source-map.js', {
+        plugins: [
+          [makeVisitor({types: babel.types}), {
+            include: ['fixtures/has-inline-source-map.js'],
+            inputSourceMap: { asdfQwer: 'foo' }
+          }]
+        ]
+      })
+      result.code.should.match(/inputSourceMap:\s*{\s*asdfQwer: "foo"\s*}/)
+    })
+  })
+
   context('package.json "nyc" config', function () {
     it('should instrument file if shouldSkip returns false', function () {
       var result = babel.transformFileSync('./fixtures/should-cover.js', {