Why doesn't my Makefile interpolate an expression in a command

Question

I'm trying to write a super simple Makefile to run the tests in a Go project. The project's dependencies are vendored, but I want to skip these tests. When running this from the command line I simply do

$ go test $(go list ./... | grep -v /vendor/)

Yet, when I put this into a Makefile like this:

test:
    go test $(go list ./... | grep -v /vendor/)

.PHONY: test

the expression will not be evaluated:

$ make
go test 
?       github.com/m90/some-repo    [no test files]

How do I get make to interpolate the expression in a shell-like manner?

Answer 1

In a Makefile recipe section you will need to escape the $ using a second $:

test:
    go test $$(go list ./... | grep -v /vendor/)

.PHONY: test

Answer 2

Depending on the circumstance, it might be more useful to evaluate the command during the expansion of the recipe using shell function:

test:
    go test $(shell go list ./... | grep -v /vendor/)

.PHONY: test

This will make the package names part of the recipe, and will normally print the result of the subcommand when executed.