How to Test Package Main in Go

Simeon Visser — Thu, 05 Jun 2014 00:00:00 GMT

There are a few things to get right when trying to test the main package in Go. This is a result of package naming rules and where files need to be located. My attempts from other testing frameworks (such as Python) led me to error messages such as:

cannot find package "mypackage" in any of: /first/path/ (from $GOROOT), /second/path/ (from $GOPATH)
can't load package: package mypackage: found packages main (mypackage.go) and mypackage (mypackage_test.go) in /project/path
./mypackage_test.go:4: import "path/to/mypackage" while compiling that package (import cycle)

However, it should be possible to resolve all these errors by following this checklist:

An executable package must have the name main (so package main).
The name of the code file can be as desired, so example.go in this example.
The name of the test file should have _test.go at the end, so example_test.go.
The test file should be in the same directory as the code file.
The package name of the test file must also be package main.
There is no need to import the code in the test file as everything is in the same package.

You don't necessarily need to have these files in a subdirectory of your project; you can have all files in the root directory of the project.

Simeon Visser (go)

How to Test Package Main in Go