travis: use a make .gitvalidation target

.travis.yml

@@ -12,15 +12,15 @@ before_script:
 
 before_install:
   - docker pull vbatts/pandoc
-  - go get github.com/vbatts/git-validation
+  - make install.tools
   - go get github.com/alecthomas/gometalinter
   - gometalinter --install --update
   - go get -t -d ./...
 
 install: true
 
 script:
-  - git-validation -run DCO,short-subject -v -range ${TRAVIS_COMMIT_RANGE}
+  - make .gitvalidation
   - make lint
   - make check-license
   - make test

Makefile

@@ -15,6 +15,8 @@ FIGURE_FILES := \
 OUTPUT		?= output/
 DOC_FILENAME	?= oci-image-spec
 
+EPOCH_TEST_COMMIT ?= v0.2.0
+
 default: help
 
 help:
@@ -82,6 +84,23 @@ test:
 img/%.png: %.dot
 	dot -Tpng $^ > $@
 
+.PHONY: .gitvalidation
+
+# When this is running in travis, it will only check the travis commit range
+.gitvalidation:
+	@which git-validation > /dev/null 2>/dev/null || (echo "ERROR: git-validation not found. Consider 'make install.tools' target" && false)
+ifeq ($(TRAVIS),true)
+	git-validation -q -run DCO,short-subject,dangling-whitespace
+else
+	git-validation -v -run DCO,short-subject,dangling-whitespace -range $(EPOCH_TEST_COMMIT)..HEAD
+endif
+
+.PHONY: install.tools
+install.tools: .install.gitvalidation
+
+.install.gitvalidation:
+	go get github.com/vbatts/git-validation
+
 clean:
 	rm -rf *~ $(OUTPUT)
 .PHONY: \