Use CircleCI workflows (#35)

Improves feedback in checks UI

Author: marcqualie

.circleci/config.yml

@@ -1,13 +1,39 @@
 version: 2.1
 
 jobs:
-  build:
+  bundle:
     docker:
-      - image: circleci/ruby:2.6.6
+      - image: circleci/ruby:2.7.1
     working_directory: /mnt/ramdisk
     steps:
       - checkout
-      - run: bundle install
+      - restore_cache:
+          keys:
+            - bundler-{{ checksum "diffcrypt.gemspec" }}-{{ .Environment.CACHE_VERSION }}
+      - run:
+          name: bundle install
+          command: |
+            gem install bundler -v '2.1.4'
+            bundle install --path=vendor/bundle --jobs=4 --retry=3
+      - save_cache:
+          key: bundler-{{ checksum "diffcrypt.gemspec" }}-{{ .Environment.CACHE_VERSION }}
+          paths:
+            - vendor/bundle
+
+  test:
+    docker:
+      - image: circleci/ruby:2.7.1
+    working_directory: /mnt/ramdisk
+    steps:
+      - checkout
+      - restore_cache:
+          keys:
+            - bundler-{{ checksum "diffcrypt.gemspec" }}-{{ .Environment.CACHE_VERSION }}
+      - run:
+          name: bundle install
+          command: |
+            gem install bundler -v '2.1.4'
+            bundle install --path=vendor/bundle --jobs=4 --retry=3
       - run:
           name: Setup Code Climate test-reporter
           command: |
@@ -20,7 +46,33 @@ jobs:
             ./cc-test-reporter before-build
             bundle exec rake test
             ./cc-test-reporter after-build --coverage-input-type lcov --exit-code $?
+  rubocop:
+    docker:
+      - image: circleci/ruby:2.7.1
+    working_directory: /mnt/ramdisk
+    steps:
+      - checkout
+      - restore_cache:
+          keys:
+            - bundler-{{ checksum "diffcrypt.gemspec" }}-{{ .Environment.CACHE_VERSION }}
+      - run:
+          name: bundle install
+          command: |
+            gem install bundler -v '2.1.4'
+            bundle install --path=vendor/bundle --jobs=4 --retry=3
       - run:
           name: rubocop
           command: bundle exec rubocop
           when: always
+
+workflows:
+  version: 2
+  all:
+    jobs:
+      - bundle
+      - test:
+          requires:
+            - bundle
+      - rubocop:
+          requires:
+            - bundle