From 628af48e2f7ab279c52f4355c0ccb92ac16b2c1a Mon Sep 17 00:00:00 2001
From: Joseph Mordetsky <jmordetsky@gmail.com>
Date: Fri, 27 Mar 2020 14:41:21 -0400
Subject: [PATCH] fix: handle sourcemap `sources` emtpy edge case (#94)

---
 lib/v8-to-istanbul.js                       |  2 +-
 test/fixtures/scripts/empty.compiled.js     |  3 +++
 test/fixtures/scripts/empty.compiled.js.map |  1 +
 test/fixtures/scripts/empty.js              |  0
 test/v8-to-istanbul.js                      | 20 ++++++++++++++++++--
 5 files changed, 23 insertions(+), 3 deletions(-)
 create mode 100644 test/fixtures/scripts/empty.compiled.js
 create mode 100644 test/fixtures/scripts/empty.compiled.js.map
 create mode 100644 test/fixtures/scripts/empty.js

diff --git a/lib/v8-to-istanbul.js b/lib/v8-to-istanbul.js
index 283f3d36..26f1e52c 100644
--- a/lib/v8-to-istanbul.js
+++ b/lib/v8-to-istanbul.js
@@ -73,7 +73,7 @@ module.exports = class V8ToIstanbul {
 
   _rewritePath (rawSourceMap) {
     const sourceRoot = rawSourceMap.sourcemap.sourceRoot ? rawSourceMap.sourcemap.sourceRoot.replace('file://', '') : ''
-    const sourcePath = rawSourceMap.sourcemap.sources[0].replace('file://', '')
+    const sourcePath = rawSourceMap.sourcemap.sources.length >= 1 ? rawSourceMap.sourcemap.sources[0].replace('file://', '') : rawSourceMap.sourcemap.file
     const candidatePath = join(sourceRoot, sourcePath)
 
     if (isAbsolute(candidatePath)) {
diff --git a/test/fixtures/scripts/empty.compiled.js b/test/fixtures/scripts/empty.compiled.js
new file mode 100644
index 00000000..f33e6e13
--- /dev/null
+++ b/test/fixtures/scripts/empty.compiled.js
@@ -0,0 +1,3 @@
+
+
+//# sourceMappingURL=empty.compiled.js.map
\ No newline at end of file
diff --git a/test/fixtures/scripts/empty.compiled.js.map b/test/fixtures/scripts/empty.compiled.js.map
new file mode 100644
index 00000000..196ae77a
--- /dev/null
+++ b/test/fixtures/scripts/empty.compiled.js.map
@@ -0,0 +1 @@
+{"version":3,"sources":[],"names":[],"mappings":"","file":"empty.compiled.js"}
\ No newline at end of file
diff --git a/test/fixtures/scripts/empty.js b/test/fixtures/scripts/empty.js
new file mode 100644
index 00000000..e69de29b
diff --git a/test/v8-to-istanbul.js b/test/v8-to-istanbul.js
index 12eed5b9..10004967 100644
--- a/test/v8-to-istanbul.js
+++ b/test/v8-to-istanbul.js
@@ -1,5 +1,4 @@
-/* global describe, it */
-
+/* global describe, it, beforeEach, afterEach */
 const { readdirSync, lstatSync, writeFileSync, readFileSync } = require('fs')
 const path = require('path')
 const runFixture = require('./utils/run-fixture')
@@ -90,6 +89,23 @@ ${'//'}${'#'} sourceMappingURL=data:application/json;base64,${base64Sourcemap}
       v8ToIstanbul.sourceTranspiled.should.not.be.undefined()
     })
   })
+  describe('source map format edge cases', () => {
+    let consoleWarn
+    beforeEach(() => {
+      consoleWarn = console.warn
+      console.warn = () => { throw new Error('Test should not invoke console.warn') }
+    })
+    afterEach(() => {
+      console.warn = consoleWarn
+    })
+    it('should handle empty sources in a sourcemap', async () => {
+      const v8ToIstanbul = new V8ToIstanbul(
+        `file://${require.resolve('./fixtures/scripts/empty.compiled.js')}`,
+        0
+      )
+      await v8ToIstanbul.load()
+    })
+  })
 
   // execute JavaScript files in fixtures directory; these
   // files contain the raw v8 output along with a set of