Simple makefile tests

Getting a handle on testing requires you become comfortable writing test. The place to start is with the simplest test you can think of. Even though Make will notify you if a file is missing, learning how to write these simple test and to format useful output is a valuable skill to practice.

Helper variable for a timestamp:
​DTS = $(shell date +%Y-%m-%dT%H:%M:%S-%Z)

Test for a directory:
define test_dir
    # tests the directory in the <first dependency>
    if ! test -d $<; \
    then echo $(DTS)    [FAIL] - $< does not exist; \
    else true; fi
endef

ROOTDIR := $(shell pwd)
​
ROOTDIR: $(ROOTDIR)
    @$(test_dir)

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