[DI] Handle unknown path prefixes in probe file paths

If there's no match for a known script based on the probe file path
provided via RC, try to remove the base directory and try to match
again. Continue this approach, until there's no more directories in the
path.

This can happen if the user-provided file path contains a base
directory, but this directory isn't part of the deployed code base.
This would for example be the case if the files are stored in a
sub-directory in the git repo, but deployed into a different directory
in production.

packages/dd-trace/src/debugger/devtools_client/state.js

@@ -24,12 +24,22 @@ module.exports = {
    * To fix this, specify a more unique file path, e.g `demo-project1/index.js` instead of `index.js`
    *
    * @param {string} path
-   * @returns {[string, string] | undefined}
+   * @returns {[string, string, string | undefined] | undefined}
    */
   findScriptFromPartialPath (path) {
-    return scriptIds
-      .filter(([url]) => url.endsWith(path))
-      .sort(([a], [b]) => a.length - b.length)[0]
+    do {
+      const result = scriptIds
+        .filter(([url]) => url.endsWith(path))
+        .sort(([a], [b]) => a.length - b.length)[0]
+
+      if (result === undefined) {
+        const index = path.indexOf('/')
+        if (index === -1) return
+        path = path.slice(index + 1)
+      } else {
+        return result
+      }
+    } while (true)
   },
 
   getStackFromCallFrames (callFrames) {

packages/dd-trace/test/debugger/devtools_client/state.spec.js

@@ -0,0 +1,64 @@
+'use strict'
+
+require('../../setup/mocha')
+
+describe('findScriptFromPartialPath', function () {
+  let state
+
+  before(function () {
+    state = proxyquire('../src/debugger/devtools_client/state', {
+      './session': {
+        '@noCallThru': true,
+        on (event, listener) {
+          if (event === 'Debugger.scriptParsed') {
+            listener({ params: { scriptId: 'script-id', url: 'file:///path/to/foo.js' } })
+          }
+        }
+      }
+    })
+  })
+
+  describe('full path matches', function () {
+    it('with a "file:" protocol', testPath('file:///path/to/foo.js'))
+
+    it('with a root slash', testPath('/path/to/foo.js'))
+
+    it('without a root slash', testPath('path/to/foo.js'))
+  })
+
+  describe('partial path matches', function () {
+    it('fewer directories', testPath('to/foo.js'))
+
+    it('no directories', testPath('foo.js'))
+  })
+
+  describe('path contains directory prefix', function () {
+    it('prefixed with unknown directory', testPath('prefix/to/foo.js'))
+
+    it('prefixed with two unknown directories', testPath('prefix1/prefix2/to/foo.js'))
+  })
+
+  describe('circuit breakers', function () {
+    it('should abort if the path is unknown', function () {
+      const result = state.findScriptFromPartialPath('this/path/does/not/exist.js')
+      expect(result).to.be.undefined
+    })
+
+    it('should abort if the path is undefined', function () {
+      const result = state.findScriptFromPartialPath(undefined)
+      expect(result).to.be.undefined
+    })
+
+    it('should abort if the path is an empty string', function () {
+      const result = state.findScriptFromPartialPath('')
+      expect(result).to.be.undefined
+    })
+  })
+
+  function testPath (path) {
+    return function () {
+      const result = state.findScriptFromPartialPath(path)
+      expect(result).to.deep.equal(['file:///path/to/foo.js', 'script-id', undefined])
+    }
+  }
+})