server: fixes #1124, clear the disk cache whenever launching the browser

packages/server/lib/browsers/chrome.coffee

@@ -129,19 +129,23 @@ module.exports = {
           args = newArgs
     .then =>
       Promise.all([
-        ## ensure that we have a chrome profile dir
-        utils.ensureProfile(browserName)
+        ## ensure that we have a clean cache dir
+        ## before launching the browser every time
+        utils.ensureCleanCache(browserName)
 
         @_writeExtension(options.proxyUrl, options.socketIoRoute)
       ])
-    .spread (dir, dest) ->
+    .spread (cacheDir, dest) ->
       ## normalize the --load-extensions argument by
       ## massaging what the user passed into our own
       args = _normalizeArgExtensions(dest, args)
 
+      userDir = utils.getProfileDir(browserName)
+
       ## this overrides any previous user-data-dir args
       ## by being the last one
-      args.push("--user-data-dir=#{dir}")
+      args.push("--user-data-dir=#{userDir}")
+      args.push("--disk-cache-dir=#{cacheDir}")
 
       debug("launch in chrome: %s, %s", url, args)
 

packages/server/lib/browsers/electron.coffee

@@ -79,12 +79,22 @@ module.exports = {
       if ua = options.userAgent
         @_setUserAgent(win.webContents, ua)
 
-      if ps = options.proxyServer
-        @_setProxy(win.webContents, ps)
+      setProxy = =>
+        if ps = options.proxyServer
+          @_setProxy(win.webContents, ps)
+
+      Promise.join(
+        setProxy(),
+        @_clearCache(win.webContents)
+      )
     .then ->
       win.loadURL(url)
     .return(win)
 
+  _clearCache: (webContents) ->
+    new Promise (resolve) ->
+      webContents.session.clearCache(resolve)
+
   _setUserAgent: (webContents, userAgent) ->
     ## set both because why not
     webContents.setUserAgent(userAgent)

packages/server/lib/browsers/utils.coffee

@@ -9,10 +9,17 @@ fs = Promise.promisifyAll(fs)
 profiles = appData.path("browsers")
 
 module.exports = {
-  ensureProfile: (name) ->
-    p = path.join(profiles, name)
+  getProfileDir: (name) ->
+    path.join(profiles, name)
 
-    fs.ensureDirAsync(p).return(p)
+  ensureCleanCache: (name) ->
+    p = path.join(profiles, name, "CypressCache")
+
+    fs
+    .removeAsync(p)
+    .then ->
+      fs.ensureDirAsync(p)
+    .return(p)
 
   copyExtension: (src, dest) ->
     fs.copyAsync(src, dest)

packages/server/test/e2e/cache_spec.coffee

@@ -8,6 +8,8 @@ replacerRe = /(<h1>)\w+(<\/h1>)/
 
 e2ePath = Fixtures.projectPath("e2e")
 
+requestsForCache = 0
+
 onServer = (app) ->
   app.post "/write/:text", (req, res) ->
     file = path.join(e2ePath, "index.html")
@@ -19,6 +21,13 @@ onServer = (app) ->
       fs.writeFile file, str, (err) ->
         res.sendStatus(200)
 
+  app.get "/cached", (req, res) ->
+    requestsForCache += 1
+
+    res
+    .set("cache-control", "public, max-age=3600")
+    .send("this response will be disk cached")
+
 describe "e2e cache", ->
   e2e.setup({
     servers: {
@@ -37,3 +46,21 @@ describe "e2e cache", ->
       snapshot: true
       expectedExitCode: 0
     })
+
+  it "clears cache when browser is spawned", ->
+    e2e.exec(@, {
+      spec: "cache_clearing_spec.coffee"
+      expectedExitCode: 0
+    })
+    .then =>
+      ## only 1 request should have gone out
+      expect(requestsForCache).to.eq(1)
+
+      e2e.exec(@, {
+        spec: "cache_clearing_spec.coffee"
+        expectedExitCode: 0
+      })
+      .then ->
+        ## and after the cache is cleaned before
+        ## opening the browser, it'll make a new request
+        expect(requestsForCache).to.eq(2)

packages/server/test/scripts/e2e.js

@@ -14,6 +14,10 @@ const glob = Promise.promisify(require('glob'))
 
 const options = minimist(process.argv.slice(2))
 
+if (options.browser) {
+  process.env.BROWSER = options.browser
+}
+
 const started = new Date()
 
 let numFailed = 0

packages/server/test/support/fixtures/projects/e2e/cypress/integration/cache_clearing_spec.coffee

@@ -0,0 +1,15 @@
+req = (win) ->
+  new Promise (resolve, reject) ->
+    rand = Math.random()
+
+    xhr = new win.XMLHttpRequest()
+    xhr.open("GET", "http://localhost:1515/cached/")
+    xhr.onload = -> resolve(win)
+    xhr.onerror = reject
+    xhr.send()
+
+it "makes cached request", ->
+  cy
+    .visit("http://localhost:1515")
+    .then(req) ## this creates the disk cache
+    .then(req) ## this should not hit our server

packages/server/test/unit/browsers/electron_spec.coffee

@@ -68,6 +68,7 @@ describe "lib/browsers/electron", ->
   context "._launch", ->
     beforeEach ->
       @sandbox.stub(menu, "set")
+      @sandbox.stub(electron, "_clearCache").resolves()
       @sandbox.stub(electron, "_setProxy").resolves()
       @sandbox.stub(electron, "_setUserAgent")