Converting to go 1.11 modules

[smyrman]

Removes vendored version of hysterix.

Initattes two new go module roots:

• One for the git root
• One for the examples/ sub-directory

Resolves #209

[smyrman]

The example_test.go was moved to the examples/ folder to get the mod file to detect less dependencies. The examples/ folder got it's own mod file, with a replace directive for the rest-layer dependency.

Any opinions on this approach @rs?

[rs]

I don't think you need to do that. Just do no run go test before committing the go.mod and test deps won't be added.

[Dragomir-Ivanov]

go mod init github.com/rs/rest-layer; go mod tidy

Always includes test deps, without any go test run, after the above command.

[smyrman]

It's certainly possible to exclude test deps from go.mod, but it doesn't look to be best-practice. From https://github.com/golang/go/wiki/Modules#how-to-prepare-for-a-release, there are two relevant recommendations for preparing a release of your go module:

1. Run go mod tidy. This command is the only command to remove unused dependencies, but it will also add any test dependencies.
2. Run go test all [redefined in Go module mode] to test your module (including running the tests for your direct and indirect dependencies) as a way of validating that the currently selected packages versions are compatible.

For the latter, test dependencies are defenantly best added to the go.mod. As @Dragomir-Ivanov pointed out earlier though, test dependencies are not downloaded when building a module that depend on rest-layer; only their go.mod files are. They would be for go test all, of course.

As for moving the exmaple_test.go to examples, a better alternative for keeping the amount of dependencies down in the main module, would be to rewrite it to only depend on the standard library (e.g. http.Handler, the default logger etc).

[smyrman]

As for adding a separate go module root in the examples/ directory, that makes (as far as I know) anything depending on rest-layer, or commands run against rest-layer, including go test ./..., completely ignore the examples/ directory. I think this is reasonable - the dependencies found in the example are completely irrelevant for rest-layer as a library - but I can't claim there is a precedence in the community for doing it in this way yet.

[smyrman]

As for moving the example_test.go to examples/, a better alternative for keeping the amount of dependencies down in the main module, would be to rewrite it to only depend on the standard library (e.g. http.Handler, the default logger etc).

I have done an attempt on this. Kept the cors dependency as it's hard to avoid, and is already included in another test.

[Dragomir-Ivanov]

cors is fine I guess. It is needed during development, anyway.

[smyrman]

I will go ahead and merge this.