Use BATS for testing

Switches testing to the BATS testing framework:
https://github.com/bats-core/bats-core

test-build.sh

@@ -46,7 +46,9 @@ function build() {
   info "Build of ${full_tag} succeeded."
 
   info "Testing ${full_tag}"
-  docker run --rm -v "$PWD/test-image.sh:/usr/local/bin/test.sh" node:"${full_tag}" test.sh "${full_version}"
+  export full_tag=${full_tag}
+  export full_version=${full_version}
+  bats test-image.bats
 }
 
 cd "$(cd "${0%/*}" && pwd -P)" || exit

test-image.bats

@@ -0,0 +1,17 @@
+#!/usr/bin/env bats
+
+@test "Test for node and version" {
+  run docker run --rm -it node:"$full_tag" node -e "process.stdout.write(process.versions.node)"
+  [ "$status" -eq 0 ]
+  [ "$output" == "${full_version}" ]
+}
+
+@test "Test for npm" {
+  run docker run --rm -it node:"$full_tag" npm --version
+  [ "$status" -eq 0 ]
+}
+
+@test "Test for yarn" {
+  run docker run --rm -it node:"$full_tag" yarn --version
+  [ "$status" -eq 0 ]
+}

test-image.sh

@@ -1,18 +0,0 @@
-#!/bin/sh
-if [ "$(node -e "process.stdout.write(process.versions.node)")" != "${1}" ]; then
-  echo "Test for node failed!"
-  exit 1
-fi
-echo "Test for node succeeded."
-
-if ! npm --version >/dev/null; then
-  echo "Test for npm failed!"
-  exit 1
-fi
-echo "Test for npm succeeded."
-
-if ! yarn --version >/dev/null; then
-  echo "Test of yarn failed!"
-  exit 1
-fi
-echo "Test for yarn succeeded."