go not running program with name package_test.go

You can't name your program files as *_test.go as this is part of integrated Go testing system

To write a new test suite, create a file whose name ends _test.go that contains the TestXxx functions as described here. Put the file in the same package as the one being tested. The file will be excluded from regular package builds but will be included when the “go test” command is run. For more detail, run “go help test” and “go help testflag”.

Just rename package_test.go to packagetest.go

Not a bug, it's designed so. go run detects the _test files and consider them as test files for a package, test files will be compiled as a separate package, and then linked and run with the main test binary.
It's recommended to put your package file to GOPATH/src/PACK_NAME/, then run your *_test.go with go test.