How to set child process' environment variable in Makefile

Make variables are not exported into the environment of processes make invokes... by default. However you can use make's export to force them to do so. Change:

test: NODE_ENV = test

to this:

test: export NODE_ENV = test

(assuming you have a sufficiently modern version of GNU make >= 3.77 ).

As MadScientist pointed out, you can export individual variables with:

export MY_VAR = foo  # Available for all targets

Or export variables for a specific target (target-specific variables):

my-target: export MY_VAR_1 = foo
my-target: export MY_VAR_2 = bar
my-target: export MY_VAR_3 = baz

my-target: dependency_1 dependency_2
  echo do something

You can also specify the .EXPORT_ALL_VARIABLES target to—you guessed it!—EXPORT ALL THE THINGS!!!:

.EXPORT_ALL_VARIABLES:

MY_VAR_1 = foo
MY_VAR_2 = bar
MY_VAR_3 = baz

test:
  @echo $$MY_VAR_1 $$MY_VAR_2 $$MY_VAR_3

see .EXPORT_ALL_VARIABLES