Add --clean option to the style checker

Closes #8

README.md

@@ -75,6 +75,13 @@ It probably makes sense to put `style-check` in either the `pre` or
 - `GITHUB_ACCESS_TOKEN`: A Github API auth token for a user with commit
   access to your repo. (Can also be set with the `-g` option.)
 
+`style-check` also has the following option:
+
+- `--clean`: Cleans old comments from the pull request before commenting again,
+  to avoid double-commenting for the same issue. *Warning: only use this option
+  if you have a special Github user for Circlemator, otherwise you may end up
+  accidentally deleting user code review comments!*
+
 ### Self-merge release branch
 
 Preamble: at Rainforest, our process for getting code into production

exe/circlemator

@@ -28,6 +28,10 @@ parser = OptionParser.new do |opts|
     options[:circle_api_token] = t
   end
 
+  opts.on('--clean', 'Clean existing comments before commenting on a pull request') do
+    options[:clean] = true
+  end
+
   opts.on('-h', '--help', 'Print this help message') do
     puts opts
     exit

lib/circlemator/github_repo.rb

@@ -17,6 +17,12 @@ def initialize(url, repo)
       end
     end
 
+    class BadResponseError < StandardError
+      def initialize(response)
+        super "Bad response from github: #{response.inspect}"
+      end
+    end
+
     base_uri 'https://api.github.com/repos'
 
     def initialize(user:, repo:, github_auth_token:, **_opts)
@@ -33,6 +39,10 @@ def put(path, opts = {})
       self.class.put(fix_path(path), opts.merge(basic_auth: auth))
     end
 
+    def delete(path, opts = {})
+      self.class.delete(fix_path(path), opts.merge(basic_auth: auth))
+    end
+
     private
 
     def fix_path(path)

lib/circlemator/pr_cleaner.rb

@@ -0,0 +1,36 @@
+# frozen_string_literal: true
+require 'circlemator/github_repo'
+
+module Circlemator
+  class PrCleaner
+    def initialize(github_repo:, pr_url:)
+      @github_repo = github_repo
+      @pr_url = pr_url
+      get_user_id
+    end
+
+    def clean!
+      response = @github_repo.get("#{@pr_url}/comments")
+      if response.code != 200
+        raise ::Circlemator::GithubRepo::BadResponseError, response
+      end
+
+      comments = JSON.parse(response.body)
+      comments.each do |comment|
+        if comment.dig('user', 'id') == @user_id
+          @github_repo.delete("#{@pr_url}/comments/#{comment.fetch('id')}")
+        end
+      end
+    end
+
+    private
+
+    def get_user_id
+      response = @github_repo.get('/user')
+      if response.code != 200
+        raise ::Circlemator::GithubRepo::BadResponseError, response
+      end
+      @user_id = JSON.parse(response.body).fetch('id')
+    end
+  end
+end

lib/circlemator/pr_finder.rb

@@ -3,12 +3,6 @@
 
 module Circlemator
   class PrFinder
-    class BadResponseError < StandardError
-      def initialize(response)
-        super "Bad response from github: #{response.inspect}"
-      end
-    end
-
     def initialize(github_repo:, base_branch:, compare_branch:, sha:, **_opts)
       @github_repo = github_repo
       @base_branch = base_branch
@@ -19,7 +13,7 @@ def initialize(github_repo:, base_branch:, compare_branch:, sha:, **_opts)
     def find_pr
       response = @github_repo.get '/pulls', query: { base: @base_branch }
       if response.code != 200
-        raise BadResponseError, response
+        raise ::Circlemator::GithubRepo::BadResponseError, response
       end
 
       prs = JSON.parse(response.body)

lib/circlemator/style_checker.rb

@@ -5,6 +5,7 @@
 require 'pronto/rubocop'
 require 'pronto/commentator'
 require 'circlemator/pr_finder'
+require 'circlemator/pr_cleaner'
 
 module Circlemator
   class StyleChecker
@@ -14,8 +15,11 @@ def initialize(opts)
     end
 
     def check!
-      pr_number, _ = PrFinder.new(@opts).find_pr
+      pr_number, pr_url = PrFinder.new(@opts).find_pr
       if pr_number
+        if @opts[:clean]
+          PrCleaner.new(github_repo: @opts.fetch(:github_repo), pr_url: pr_url).clean!
+        end
         ENV['PULL_REQUEST_ID'] = pr_number.to_s
         formatter = ::Pronto::Formatter::GithubPullRequestFormatter.new
       else

spec/circlemator/pr_cleaner_spec.rb

@@ -0,0 +1,75 @@
+# frozen_string_literal: true
+require 'circlemator/pr_cleaner'
+require 'circlemator/github_repo'
+require 'json'
+
+RSpec.describe Circlemator::PrCleaner do
+  describe '#clean!' do
+    let(:github_repo) do
+      Circlemator::GithubRepo.new(user: 'octocat', repo: 'Hello-World', github_auth_token: 'abc123')
+    end
+    let(:pr_url) { 'https://api.github.com/repos/octocat/Hello-World/pulls/1347' }
+    let(:cleaner) do
+      described_class.new github_repo: github_repo,
+                          pr_url: pr_url
+    end
+    let(:user_id) { 7 }
+    let(:user_response) do
+      {
+        'login' => 'octocat',
+        'id' => user_id,
+      }.to_json
+    end
+    let(:comments_response) do
+      [
+        {
+          'id' => 1,
+          'user' => {
+            'id' => user_id,
+          },
+        },
+        {
+          'id' => 2,
+          'user' => {
+            'id' => user_id + 1,
+          },
+        },
+        {
+          'id' => 3,
+          'user' => {
+            'id' => user_id,
+          },
+        },
+      ].to_json
+    end
+
+    subject { cleaner.clean! }
+
+    before do
+      allow(github_repo)
+        .to receive(:get).with('/user').and_return double(code: 200, body: user_response)
+      allow(github_repo)
+        .to receive(:get).with("#{pr_url}/comments").and_return double(code: 200, body: comments_response)
+    end
+
+    context 'with a successful response' do
+      it 'deletes all the comments for the PR for the authenticated user' do
+        expect(github_repo).to receive(:delete).with(%r(comments/1)).once
+        expect(github_repo).to receive(:delete).with(%r(comments/3)).once
+        expect(github_repo).to_not receive(:delete).with(%r(comments/2))
+
+        subject
+      end
+    end
+
+    context 'with an unsuccessful response' do
+      before do
+        allow(github_repo).to receive(:get).and_return double(code: 500, body: 'BAD')
+      end
+
+      it 'raises an error' do
+        expect { subject }.to raise_error Circlemator::GithubRepo::BadResponseError
+      end
+    end
+  end
+end

spec/circlemator/pr_finder_spec.rb

@@ -58,7 +58,7 @@
       end
 
       it 'raises an error' do
-        expect { subject }.to raise_error Circlemator::PrFinder::BadResponseError
+        expect { subject }.to raise_error Circlemator::GithubRepo::BadResponseError
       end
     end
 

spec/circlemator/style_checker_spec.rb

@@ -37,6 +37,22 @@
 
         expect(ENV['PULL_REQUEST_ID']).to eq pr_number.to_s
       end
+
+      context 'with the --clean option' do
+        let(:checker) do
+          Circlemator::StyleChecker.new github_repo: github_repo,
+                                        sha: 'abc123',
+                                        base_branch: 'master',
+                                        compare_branch: 'topic',
+                                        clean: true
+        end
+
+        it 'cleans existing comments before running pronto' do
+          expect(Circlemator::PrCleaner).to receive(:new).and_return double(clean!: nil)
+
+          subject
+        end
+      end
     end
 
     context 'without an open PR' do