Refactor Makefile and specs to allow running a narrow spec target.

Author: jemc

Makefile

@@ -13,10 +13,16 @@ test: PHONY
 	docker exec -ti mare-dev make extra_args="$(extra_args)" test.inner
 /tmp/bin/spec: $(shell find src -name '*.cr') $(shell find spec -name '*.cr')
 	mkdir -p /tmp/bin
-	crystal build --debug spec/spec_helper.cr -o $@
+	crystal build --debug spec/all.cr -o $@
 test.inner: PHONY /tmp/bin/spec
 	echo && /tmp/bin/spec $(extra_args)
 
+# Run a narrow target within the test suite.
+test.narrow: PHONY
+	docker exec -ti mare-dev make target="$(target)" test.narrow.inner
+test.narrow.inner: PHONY
+	crystal spec spec/spec_helper.cr "$(target)"
+
 # Evaluate a Hello World example.
 example-eval: PHONY
 	docker exec -ti mare-dev make extra_args="$(extra_args)" example-eval.inner

spec/all.cr

@@ -0,0 +1 @@
+require "./**"

spec/spec_helper.cr

@@ -1,6 +1,5 @@
 require "spec"
 require "../src/mare"
-require "./**"
 
 module Spec::Methods
   def fixture(*parts)