1 files changed, 59 insertions, 0 deletions

diff --git a/lib/pronto/eslint_npm.rb b/lib/pronto/eslint_npm.rb
new file mode 100644
index 0000000..afbae59
--- /dev/null
+++ b/lib/pronto/eslint_npm.rb
@@ -0,0 +1,59 @@
+require 'pronto'
+
+module Pronto
+  class ESLintNpm < Runner
+    def run
+      return [] unless @patches
+
+      @patches.select { |patch| patch.additions > 0 }
+        .select { |patch| js_file?(patch.new_file_full_path) }
+        .map { |patch| inspect(patch) }
+        .flatten.compact
+    end
+
+    def inspect(patch)
+      @_repo_path ||= @patches.first.repo.path
+
+      offences = run_eslint(patch)
+      clean_up_eslint_output(offences)
+        .map do |offence|
+          patch
+            .added_lines
+            .select { |line| line.new_lineno == offence['line'] }
+            .map { |line| new_message(offence, line) }
+        end
+    end
+
+    private
+
+    def new_message(offence, line)
+      path = line.patch.delta.new_file[:path]
+      level = :warning
+
+      Message.new(path, line, level, offence['message'], nil, self.class)
+    end
+
+    def js_file?(path)
+      %w(.js .es6 .js.es6).include?(File.extname(path))
+    end
+
+    def run_eslint(patch)
+      Dir.chdir(@_repo_path) do
+        JSON.parse(
+          `eslint #{Shellwords.escape(patch.new_file_full_path.to_s)} -f json`
+        )
+      end
+    end
+
+    # rubocop:disable Metrics/LineLength
+    def clean_up_eslint_output(output)
+      # 1. Filter out offences without a warning or error
+      # 2. Get the messages for that file
+      # 3. Ignore errors without a line number for now
+      output
+        .select { |offence| offence['errorCount'] + offence['warningCount'] > 0 }
+        .map { |offence| offence['messages'] }
+        .flatten.select { |offence| offence['line'] }
+    end
+  end
+end