testing: document that example output must use // (and avoid gofmt flakiness)

[gopherbot]

by daviddengcn:

Before filing a bug, please check whether it has been fixed since the
latest release. Search the issue tracker and check that you're running the
latest version of Go:

Run "go version" and compare against
http://golang.org/doc/devel/release.html  If a newer version of Go exists,
install it and retry what you did to reproduce the problem.

Thanks.

What steps will reproduce the problem?
If possible, include a link to a program on play.golang.org.
1.
2.
3.

What is the expected output?
After "go fmt" my example cases are not failed

What do you see instead?
They are failed by tabs

Which compiler are you using (5g, 6g, 8g, gccgo)?

Which operating system are you using?
MacOS


Which version are you using?  (run 'go version')
1.0.3

Please provide any additional information below.
More information: https://groups.google.com/forum/#!topic/golang-nuts/ZH5YgwmjCXk

[rsc]

Comment 1:

Let's document that example output must use // comments.

[natefinch]

Comment 2:

Is there any interest in just fixing it so that a common indent is stripped off?  An
example here:
http://play.golang.org/p/u5P7NZ_Cvj

[rsc]

Comment 3:

I would rather just document it. Stripping common indent is full of
problems too.

[davecheney]

Comment 4:

Issue #4811 has been merged into this issue.

[adg]

Comment 6:

This issue was closed by revision 2482ef7.

Status changed to Fixed.