golang compiling the same package from two different file locations

The way I have my projects structured is similar to the following

/workspace
  /src
    /package1
  /vendor
    /src
      /somepackage
      /anotherpackage
      /package1

My GOPATH is set to /workspace;/workspace/vendor

Note this is not using the go 1.5 vendor option.

So far everything has been compiling and working fine within out build / development workflow.
I'm in a situation now where I would like to import a library into the vendor directory workspace/vendor/src/package1 but write some unit tests in the workspace/src/package1 directory..

When the tests run it cannot find methods from the package1 in the vendor dir.

Is there a way to get the vendor package code recognised into the same namespace like this?

Are you asking to essentially "split" the code for a package between two folders in two different gopaths? The go tool cannot do this, as it takes the first folder it finds on any folder in your gopath. If you are actively working on a project, why would it go in the vendor gopath and not in the src one?

It is because of distinctions like this that I generally recommend one gopath for everything. If you want to vendor dependencies I recommend doing that for each individual main package you have.

As captncraig said: The go tool cannot do this.

But you are free to call the go compiler itself on any set of files you want: go tool compile <file.go>...

Of course this would reintroduce some kind of Makefile style build system. It is doable but all the heavy lifting done by go build or go install is lost and will have to live in your Makefiles.