Go benchmark by function name

I have this Benchmark function:

BenchmarkMyTest(b *testing.B) {
}

And I would like to run only this function not running all other tests, but the command never worked for me.

go test -bench='BenchmarkMyTest'
or
go test -run='BenchmarkMyTest'

What's the correct way of running one single benchmark function in Go? It says to use regex but I can't find any documentation.

Thanks,

Solution

Described at Command Go: Description of testing flags:

-bench regexp
    Run benchmarks matching the regular expression.
    By default, no benchmarks run. To run all benchmarks,
    use '-bench .' or '-bench=.'.

-run regexp
    Run only those tests and examples matching the regular
    expression.

So the syntax is that you have to separate it with a space or with the equal sign (with no apostrophe marks), and what you specify is a regexp:

go test -bench BenchmarkMyTest
go test -run TestMyTest

Or:

go test -bench=BenchmarkMyTest
go test -run=TestMyTest

Specifying exactly 1 function

As the specified expression is a regexp, this will also match functions whose name contains the specified name (e.g. another function whose name starts with this, for example "BenchmarkMyTestB"). If you only want to match "BenchmarkMyTest", append the regexp word boundary '\b':

go test -bench BenchmarkMyTest\b
go test -run TestMyTest\b

Note that it's enough to append it only to the end as if the function name doesn't start with "Benchmark", it is not considered to be a benchmark function, and similarly if it doesn't start with "Test", it is not considered to be a test function (and will not be picked up anyway).