Allow %, &, and ? in spec file name.

packages/server/lib/controllers/files.coffee

@@ -6,6 +6,7 @@ glob        = require("../util/glob")
 specsUtil   = require("../util/specs")
 pathHelpers = require("../util/path_helpers")
 CacheBuster = require("../util/cache_buster")
+{ escapeFilenameInUrl } = require('../util/escape_filename')
 
 module.exports = {
   handleFiles: (req, res, config) ->
@@ -22,6 +23,10 @@ module.exports = {
 
     @getSpecs(test, config)
     .then (specs) =>
+      specs = specs.map((fileName) => 
+        return escapeFilenameInUrl(fileName)
+      )
+
       @getJavascripts(config)
       .then (js) =>
         res.render iframePath, {

packages/server/lib/project.js

@@ -28,6 +28,7 @@ const fs = require('./util/fs')
 const keys = require('./util/keys')
 const settings = require('./util/settings')
 const specsUtil = require('./util/specs')
+const { escapeFilenameInUrl } = require('./util/escape_filename')
 
 const localCwd = cwd()
 
@@ -519,11 +520,11 @@ class Project extends EE {
   normalizeSpecUrl (browserUrl, specUrl) {
     const replacer = (match) => match.replace('//', '/')
 
-    return [
+    return escapeFilenameInUrl([
       browserUrl,
       '#/tests',
       specUrl,
-    ].join('/').replace(multipleForwardSlashesRe, replacer)
+    ].join('/').replace(multipleForwardSlashesRe, replacer))
   }
 
   scaffold (cfg) {

packages/server/lib/util/escape_filename.ts

@@ -0,0 +1,17 @@
+import _ from 'lodash'
+
+const ampersandRe = /&/g
+const percentRe = /%/g
+const questionRe = /\?/g
+
+export function escapeFilenameInUrl (url: string) {
+  let paths = url.split('/')
+
+  // escape valid file name characters that cannot be used in URL
+  paths[paths.length - 1] = (_.last<string>(paths) || '')
+  .replace(percentRe, '%25') // %
+  .replace(ampersandRe, '%26') // &
+  .replace(questionRe, '%3F') // ? -> it's only valid in Linux
+
+  return paths.join('/')
+}

packages/server/test/integration/http_requests_spec.coffee

@@ -356,14 +356,18 @@ describe "Routes", ->
 
               body = res.body
 
-              expect(body.integration).to.have.length(3)
+              expect(body.integration).to.have.length(4)
 
               ## remove the absolute path key
               body.integration = _.map body.integration, (obj) ->
                 _.pick(obj, "name", "relative")
 
               expect(res.body).to.deep.eq({
                 integration: [
+                  {
+                    "name": "sub/a&b%c.js"
+                    "relative": "tests/sub/a&b%c.js"
+                  }
                   {
                     name: "sub/sub_test.coffee"
                     relative: "tests/sub/sub_test.coffee"

packages/server/test/support/fixtures/projects/todos/tests/sub/a&b%c.js

@@ -0,0 +1,4 @@
+/* eslint-disable mocha/no-global-tests */
+it('is truthy', function () {
+  expect(true).to.be.true
+})

packages/server/test/support/fixtures/server/expected_todos_all_tests_iframe.html

@@ -18,6 +18,7 @@
     </script>
     <script type="text/javascript" src="/__cypress/tests?p=tests/_support/spec_helper.js-123"></script>
     <script type="text/javascript" src="/__cypress/tests?p=tests/etc/etc.js-123"></script>
+    <script type="text/javascript" src="/__cypress/tests?p=tests/sub/a%26b%25c.js-123"></script>
     <script type="text/javascript" src="/__cypress/tests?p=tests/sub/sub_test.coffee-123"></script>
     <script type="text/javascript" src="/__cypress/tests?p=tests/test1.js-123"></script>
     <script type="text/javascript" src="/__cypress/tests?p=tests/test2.coffee-123"></script>

packages/server/test/unit/project_spec.js

@@ -698,6 +698,35 @@ This option will not have an effect in Some-other-name. Tests that rely on web s
       })
     })
 
+    it('escapses %, &', function () {
+      const todosSpec = path.join(this.todosPath, 'tests/sub/a&b%c.js')
+
+      return this.project.getSpecUrl(todosSpec)
+      .then((str) => {
+        expect(str).to.eq('http://localhost:8888/__/#/tests/integration/sub/a%26b%25c.js')
+      })
+    })
+
+    if (process.platform !== 'win32') {
+      // ? is tested here because it's valid in Unix/Linux, but invalid in Windows
+      // https://gist.github.com/doctaphred/d01d05291546186941e1b7ddc02034d3
+      it('escapes ?', function () {
+        const filePath = path.join(__dirname, '../support/fixtures/projects/todos/tests/sub/a?.spec.js')
+
+        fs.writeFileSync(filePath, '')
+
+        const todosSpec = path.join(this.todosPath, 'tests/sub/a?.spec.js')
+
+        return this.project.getSpecUrl(todosSpec)
+        .then((str) => {
+          expect(str).to.eq('http://localhost:8888/__/#/tests/integration/sub/a%3F.spec.js')
+        })
+        .then(() => {
+          fs.unlinkSync(filePath)
+        })
+      })
+    }
+
     it('returns __all spec url', function () {
       return this.project.getSpecUrl()
       .then((str) => {