Add some tests and drone to run them

.drone.yml

@@ -0,0 +1,29 @@
+---
+kind: pipeline
+name: test
+
+workspace:
+  base: "/app"
+  path: "."
+
+steps:
+
+  - name: test
+    image: python:3-alpine
+    commands:
+      - apk add bash shellcheck make gcc musl-dev libffi-dev openssl-dev
+      - pip install docker-compose
+      - make all
+
+  - name: notify
+    image: drillster/drone-email
+    settings:
+      host:
+        from_secret: SMTP_HOST  # pragma: whitelist secret
+      username:
+        from_secret: SMTP_USER  # pragma: whitelist secret
+      password:
+        from_secret: SMTP_PASS  # pragma: whitelist secret
+      from: drone@iamthefij.com
+    when:
+      status: [changed, failure]

Makefile

@@ -0,0 +1,21 @@
+.PHONY: all test clean
+
+all: test shellcheck
+
+test: test-negative test-positive
+
+.PHONY: shellcheck
+shellcheck:
+	shellcheck *.sh
+
+.PHONY: test-positive
+test-positive:
+	@echo "Check valid compose file."
+	./compose-check.sh tests/docker-compose.yml || { echo 'fail'; exit 1; }
+
+.PHONY: test-negative
+test-negative:
+	@echo "Check bad file. Should error."
+	./compose-check.sh tests/docker-compose.bad.yml && { echo 'fail'; exit 1; } || echo 'ok'
+	@echo "Check multiple files. Should error."
+	./compose-check.sh tests/docker-compose* && { echo 'fail'; exit 1; } || echo 'ok'

compose-check.sh

@@ -6,15 +6,16 @@ check_file() {
     local file=$1
     docker-compose -f "$file" config -q 2>&1 \
         | sed "/variable is not set. Defaulting/d"
-    return ${PIPESTATUS[0]}
+    return "${PIPESTATUS[0]}"
 }
 
 check_files() {
-    local all_files=$@
+    local all_files=( "$@" )
     has_error=0
-    for file in $all_files ; do
+    for file in "${all_files[@]}" ; do
         if [[ -f "$file" ]]; then
             if ! check_file "$file" ; then
+                echo "ERROR: $file"
                 has_error=1
             fi
         fi
@@ -22,7 +23,7 @@ check_files() {
     return $has_error
 }
 
-if ! check_files $@ ; then
+if ! check_files "$@" ; then
     echo "To ignore, use --no-verify"
 fi
 

tests/docker-compose.bad.yml

@@ -0,0 +1 @@
+not: valid

tests/docker-compose.yml

@@ -0,0 +1,6 @@
+---
+version: '2'
+
+services:
+  main:
+    image: busybox