go test can't find function in a same package

Question

The directory structure is :

src src/pkg src/pkg/t1.go src/pkg/t1_test.go 

---

t1.go

package pkg  import ( "fmt" )  func SayHI(){     fmt.Println("this is t1") } 

---

t1_test.go

package pkg  import (     "testing" )  func TestXYZ(t *testing.T) {     SayHI() } 

---

Invoke go test from command line at dir src/pkg

go test t1_test.go

---

error:

./t1_test.go:8: undefined: SayHI FAIL    command-line-arguments [build failed] 

but the function is there

thanks for any hints

Answer 1

It is working as intended.

jnml@fsc-r630:~/src/pkg$ go help test usage: go test [-c] [-i] [build flags] [packages] [flags for test binary]  'Go test' automates testing the packages named by the import paths. It prints a summary of the test results in the format:      ok   archive/tar   0.011s     FAIL archive/zip   0.022s     ok   compress/gzip 0.033s     ...  followed by detailed output for each failed package.  'Go test' recompiles each package along with any files with names matching the file pattern "*_test.go".  These additional files can contain test functions, benchmark functions, and example functions.  See 'go help testfunc' for more.  By default, go test needs no arguments.  It compiles and tests the package with source in the current directory, including tests, and runs the tests.  The package is built in a temporary directory so it does not interfere with the non-test installation.  In addition to the build flags, the flags handled by 'go test' itself are:      -c  Compile the test binary to pkg.test but do not run it.      -i         Install packages that are dependencies of the test.         Do not run the test.  The test binary also accepts flags that control execution of the test; these flags are also accessible by 'go test'.  See 'go help testflag' for details.  For more about build flags, see 'go help build'. For more about specifying packages, see 'go help packages'.  See also: go build, go vet. jnml@fsc-r630:~/src/pkg$  

In other words:

• go test is okay.
• go test pkg (assuming $GOPATH is ~ and the package is in ~/src/pkg) is okay.
• go test whatever_test.go is not okay as that is not supported as documented above.

To select which tests to run use the -run <regular_expression> flag (where the <regular_expression> is interpreted as having wildcards on either end, like .*<regular_expression>.*). For example

$ go test -run Say # from within the package's directory 

or

$ go test -run Say my/package/import/path # from anywhere 

Answer 2

This is somewhat strange in Golang. To be honest it took me some time to figure a way out.

A simple work-around is to include them in the command, eg: go test src/pkg/t1.go src/pkg/t1_test.go

IMHO, The best way is to keep it clean. So avoid having more than 1 file as dependency per test file. If you are using +1 file as dependency, consider creating a black-box test with a _test package and do not make use of any lowerCase internal vars.

This will avoid you having to deal with complicated dependencies on your day to day testing.