Test cases for go and appengine

Question

I am using Go and appengine, and now I would like to do some test cases.

I tried using gos standard test package, Files (both "package hello"):

hello/http.go
hello/http_test.go

Problem: I cannot run go test hello. The closest I have got is go test hello/http_test.go which works if I do not make any calls to http.go, which is quite pointless. :)

Answer 1

github.com/mzimmerman/appenginetesting

Installation

1. Install Go

2. Set the Go Environmental Variables (Your path may vary):

   export GOPATH=~/gopath
   export PATH=$PATH:$GOPATH/bin
   

3. Download the Google App Engine SDK for Go

4. Set the Google App Engine Environmental Variables (Your path may vary):

   export APPENGINE_SDK=$HOME/appengine
   export PATH=$PATH:$APPENGINE_SDK
   

5. Symlink the appengine and appengine_internal dirctories:

   ln -s $APPENGINE_SDK/goroot/src/pkg/appengine $GOPATH/src/pkg/
   ln -s $APPENGINE_SDK/goroot/src/pkg/appengine_internal $GOPATH/src/pkg/
   

6. Install appenginetesting

   go get github.com/mzimmerman/appenginetesting
   

Writing test

appengintesting provides a fake appengine.Context. Behind the scenes It's starts up a Python development server and runs the request through it, so tests can be a little bit slow (seconds instead of milliseconds). To use it in tests you write something like

import "github.com/mzimmerman/appenginetesting"
...
c := appenginetesting.NewContext(nil)

You can then use c as you would use an actual appengine.Context. This works will in the test file, but it won't work with contexts that you create by calling appengine.NewContext(r)

The strategy that I'm using in gaego is to import the context from a custom package instead of appengine. This allows me to use an appengine.Context when the build is for App Engine and use appenginetesting.Context when the build is for the test suit.

By setting the following build flags:

• context_appengine.go // +build appengine
• context_testing.go // +build !appengine

The compiler will decide which file it would like to load. Example. This techinique was taken form Gorilla

Then instead of import from appengine I import from my package E.g.

import (
  github.com/gaego/context
)

..
c := context.NewContext(r)
..

That last thing that needs to be mentioned is that you must explicitly close the context, otherwise the python processes will continue to run. You terminate the process by calling:

defer c.Close()

For more examples please view:

context_test.go

recorder_test.go

Edit: Takuya Ueda has created a brunch that works with the latest SDK

Edit2: Joshua Marsh maintains a fork that is compatible with the latest SDK

Edit3: Matt Zimmerman maintains a fork with additional features over the standard aetest package (Login/Logout & Task Queues)

Answer 2

An interesting development: as of 1.8.6 using service stubs for testing has been integrated into the SDK through the "appengine/aetest" package. This works largely like the above via a "testing" context. More info