feat: adds support for 1:many source maps (#238)

Adds support for 1:many source-maps. These source maps are used by tools
like rollup or WebPack to bundle multiple JavaScript source files into one.

Refs: istanbuljs/v8-to-istanbul#102

package.json

@@ -43,7 +43,7 @@
     "istanbul-reports": "^3.0.2",
     "rimraf": "^3.0.0",
     "test-exclude": "^6.0.0",
-    "v8-to-istanbul": "^4.1.2",
+    "v8-to-istanbul": "^5.0.0",
     "yargs": "^15.0.0",
     "yargs-parser": "^18.0.0"
   },

test/fixtures/source-maps/branches/branch-1.js

@@ -0,0 +1,12 @@
+const branch = require('./branch-2')
+
+if (false) {
+  console.info('unreachable')
+} else if (true) {
+  console.info('reachable')
+} else {
+  console.info('unreachable')
+}
+
+branch(true)
+branch(false)

test/fixtures/source-maps/branches/branch-2.js

@@ -0,0 +1,9 @@
+module.exports = function branch (a) {
+  if (a) {
+    console.info('a = true')
+  } else if (undefined) {
+    console.info('unreachable')
+  } else {
+    console.info('a = false')
+  }
+}

test/fixtures/source-maps/classes/class-1.js

@@ -0,0 +1,5 @@
+const Foo = require('./class-2')
+
+const a = new Foo(0)
+const b = new Foo(33)
+a.methodA()

test/fixtures/source-maps/classes/class-2.js

@@ -0,0 +1,23 @@
+module.exports = class Foo {
+  constructor (x=33) {
+    this.x = x ? x : 99
+    if (this.x) {
+      console.info('covered')
+    } else {
+      console.info('uncovered')
+    }
+    this.methodC()
+  }
+  methodA () {
+    console.info('covered')
+  }
+  methodB () {
+    console.info('uncovered')
+  }
+  methodC () {
+    console.info('covered')
+  }
+  methodD () {
+    console.info('uncovered')
+  }
+}

test/integration.js

@@ -374,6 +374,31 @@ describe('c8', () => {
         output.toString('utf8').should.matchSnapshot()
       })
     })
+    describe('rollup', () => {
+      it('remaps branches', () => {
+        const { output } = spawnSync(nodePath, [
+          c8Path,
+          '--exclude="test/*.js"',
+          '--temp-directory=tmp/source-map',
+          '--clean=true',
+          nodePath,
+          require.resolve('./fixtures/source-maps/branches/branches.rollup.js')
+        ])
+        output.toString('utf8').should.matchSnapshot()
+      })
+
+      it('remaps classes', () => {
+        const { output } = spawnSync(nodePath, [
+          c8Path,
+          '--exclude="test/*.js"',
+          '--temp-directory=tmp/source-map',
+          '--clean=true',
+          nodePath,
+          require.resolve('./fixtures/source-maps/classes/classes.rollup.js')
+        ])
+        output.toString('utf8').should.matchSnapshot()
+      })
+    })
     describe('ts-node', () => {
       it('reads source-map from cache, and applies to coverage', () => {
         const { output } = spawnSync(nodePath, [

test/integration.js.snap

@@ -413,6 +413,36 @@ All files   |   70.37 |    66.67 |      60 |   70.37 |
 ,"
 `;
 
+exports[`c8 source-maps rollup remaps branches 1`] = `
+",reachable
+a = true
+a = false
+-------------|---------|----------|---------|---------|-------------------
+File         | % Stmts | % Branch | % Funcs | % Lines | Uncovered Line #s 
+-------------|---------|----------|---------|---------|-------------------
+All files    |     100 |      100 |     100 |     100 |                   
+ branch-1.js |     100 |      100 |     100 |     100 |                   
+ branch-2.js |     100 |      100 |     100 |     100 |                   
+-------------|---------|----------|---------|---------|-------------------
+,"
+`;
+
+exports[`c8 source-maps rollup remaps classes 1`] = `
+",covered
+covered
+covered
+covered
+covered
+------------|---------|----------|---------|---------|-------------------
+File        | % Stmts | % Branch | % Funcs | % Lines | Uncovered Line #s 
+------------|---------|----------|---------|---------|-------------------
+All files   |   78.57 |    85.71 |      60 |   78.57 |                   
+ class-1.js |     100 |      100 |     100 |     100 |                   
+ class-2.js |   73.91 |    85.71 |      60 |   73.91 | 7-8,15-16,21-22   
+------------|---------|----------|---------|---------|-------------------
+,"
+`;
+
 exports[`c8 source-maps ts-node reads source-map from cache, and applies to coverage 1`] = `
 ",covered
 covered

test/integration.js_10.snap

@@ -466,6 +466,36 @@ All files   |   70.37 |    66.67 |      60 |   70.37 |
 ,"
 `;
 
+exports[`c8 source-maps rollup remaps branches 1`] = `
+",reachable
+a = true
+a = false
+-------------|---------|----------|---------|---------|-------------------
+File         | % Stmts | % Branch | % Funcs | % Lines | Uncovered Line #s 
+-------------|---------|----------|---------|---------|-------------------
+All files    |     100 |      100 |     100 |     100 |                   
+ branch-1.js |     100 |      100 |     100 |     100 |                   
+ branch-2.js |     100 |      100 |     100 |     100 |                   
+-------------|---------|----------|---------|---------|-------------------
+,"
+`;
+
+exports[`c8 source-maps rollup remaps classes 1`] = `
+",covered
+covered
+covered
+covered
+covered
+------------|---------|----------|---------|---------|-------------------
+File        | % Stmts | % Branch | % Funcs | % Lines | Uncovered Line #s 
+------------|---------|----------|---------|---------|-------------------
+All files   |   78.57 |    85.71 |      60 |   78.57 |                   
+ class-1.js |     100 |      100 |     100 |     100 |                   
+ class-2.js |   73.91 |    85.71 |      60 |   73.91 | 7-8,15-16,21-22   
+------------|---------|----------|---------|---------|-------------------
+,"
+`;
+
 exports[`c8 source-maps ts-node reads source-map from cache, and applies to coverage 1`] = `
 ",covered
 covered