How to develop and test a local go module

Question

I have this script:

#!/usr/bin/env bash

set -eo pipefail

cd "$(dirname "$BASH_SOURCE")";
pth_to_make="$GOPATH/src/ores/json-logging"
mkdir -p "$pth_to_make";
rm -rf "$pth_to_make";
ln -sf "$PWD" "$pth_to_make";

however this module is not declared as a go module in go.mod...I am symlinking a different dependency into the repo to test it.

The real dependency in production is at:

"$GOPATH/src/github.com/oresoftware/json-logging"

the test path is:

"$GOPATH/src/ores/json-logging"

Now, I would just delete the real dependency path in local development, the problem is that it then just deletes the .git folder in the repo and then I end up having to download that again.

Is there some way for me to symlink over the real repo/dep folder, but not lose the git stuff? Maybe I could do:

 mv   "$GOPATH/src/github.com/oresoftware/json-logging"  "/tmp/gotemp/json-logging"
 # call the script above
 # then when I am done:
 rm -rf "$GOPATH/src/github.com/oresoftware/json-logging"
 mv "/tmp/gotemp/json-logging" "$GOPATH/src/github.com/oresoftware/json-logging"  # put it back

would that be the best way forward?

Answer 1

So to expand on my comment it sounds like what you are after is the replace directive which you can read more about here . But i've outlined a brief example below;

If we imagine the directory structure:

├── replace-directive
│   ├── go.mod
│   └── replace.go
├── sandbox
│   ├── go.mod
│   └── main.go

The replace-directive is a go module with the go.mod file containing:

module example.com/replacedirective

go 1.14

Sandbox is where we want to use this local dependency version rather than grabbing the version from example.com . So in our sandbox go.mod file we have the replace directive as follows;

module example/sandbox

require (
  example.com/replacedirective v0.0.0  // This would be your reference to your production dependency
)

replace example.com/replacedirective => ../replace-directive // This is your local dependency

go 1.14

So now when you reference the module in your code it will use your local dependency instead. No symlinks required.