Chdir changes current working directory, and registers a cleanup function to return to the previous directory.

DoOrTimeout runs a check function every interval until deadline, unless the check returns true.

ExpectExpvarDeltaWithDeadline returns a deferrable function which tests if the expvar metric with name has changed by delta within the given deadline, once the function begins.

ExpectMapExpvarMetricDeltaWithDeadline returns a deferrable function which tests if the expvar map metric with name and key has changed by delta within the given deadline, once the function begins.

ExpectNoDiff tests to see if the two interfaces have no diff.

FatalIfErr fails the test with a fatal error if err is not nil.

OpenLogFile creates a new file that emulates being a log.

OverrideStdin replaces standard input with another *os.File and restores it at the end of the test.

SetFlag sets the value of the commandline flag, and registers a cleanup function that restores the flag value.

TestGetExpvar fetches the expvar metric `name`, and returns the expvar.

TestOpenFile creates a new file called name and returns the opened file.

TestTempDir creates a temporary directory for use during tests, returning the pathname.

TimeoutTest returns a test function that executes f with a timeout, If the test does not complete in time the test is failed.