Add tests

These aren't run on drone yet as there is no pre-commit plugin!

.pre-commit-config.yaml

@@ -3,4 +3,4 @@ repos:
   - repo: https://github.com/IamTheFij/docker-pre-commit
     rev: v2.0.0
     hooks:
-      - id: hadolint
+      - id: hadolint-system

Makefile

@@ -1,11 +1,17 @@
+DOCKER_TAG = drone-pre-commit-$(USER)
+
 .PHONY: clean
 
 .PHONY: default
 default: test
 
 .PHONY: test
-test:
-	@echo noop
+test: build
+	docker run --rm -v $(shell pwd):/src:ro --workdir /src $(DOCKER_TAG) ./tests/steps.sh
+
+.PHONY: build
+build: ./Dockerfile
+	docker build -t $(DOCKER_TAG) .
 
 .PHONY: install-hooks
 install-hooks:

tests/steps.sh

@@ -0,0 +1,9 @@
+#! /bin/bash
+set -ex
+
+# These simulate commands added to a pipeline step
+
+wget -L -O /usr/bin/hadolint https://github.com/hadolint/hadolint/releases/download/v1.18.0/hadolint-Linux-x86_64
+chmod +x /usr/bin/hadolint
+
+pre-commit run --all-files