Add online_emit mode

.gitignore

@@ -8,3 +8,4 @@
 /tmp/
 
 Gemfile.lock
+coverage.json

README.md

@@ -45,6 +45,26 @@ run App
 Boot up application, do something, and access `/akainaa`.
 It will show Web UI what and how many executed.
 
+### Enable online emit mode
+
+Akainaa can emit coverage data which recorded in interval to the file.
+This feature is intended to be used with vscode-akainaa extension.
+
+```ruby
+Akainaa.start(
+  project_dir: File.expand_path(__dir__),
+  ignore_glob_patterns: %w[
+    config/application.rb
+    config/initializers/*_initializer.rb
+  ],
+  online_emit: {
+    mode: :file,
+    interval: 1, # seconds
+    output_path: '/tmp/akainaa.json',
+  },
+)
+```
+
 ## Development
 
 After checking out the repo, run `bin/setup` to install dependencies. You can also run `bin/console` for an interactive prompt that will allow you to experiment.

lib/akainaa.rb

@@ -1,6 +1,7 @@
 # frozen_string_literal: true
 
 require 'coverage'
+require 'fileutils'
 
 require_relative 'akainaa/version'
 require_relative 'akainaa/call_node_visitor'
@@ -15,7 +16,8 @@ class << self
     def start(
       project_dir:,
       ignore_glob_patterns: [],
-      hide_not_executed_files: false
+      hide_not_executed_files: false,
+      online_emit: nil
     )
       @project_dir = project_dir
       @project_dir += '/' unless @project_dir.end_with?('/')
@@ -24,8 +26,15 @@ def start(
       end
       @ignore_files = Set.new(ignore_files)
       @hide_not_executed_files = hide_not_executed_files
+      @monitor = Monitor.new
 
       Coverage.start(lines: true)
+
+      if online_emit.is_a?(Hash)
+        option = default_online_emit.merge(online_emit)
+        FileUtils.mkdir_p(File.dirname(option[:path]))
+        start_multipart_emit(option)
+      end
     end
 
     def peek_result
@@ -37,7 +46,56 @@ def peek_result
     end
 
     def reset
-      Coverage.result(stop: false, clear: true)
+      @monitor.synchronize do
+        Coverage.result(stop: false, clear: true)
+        @previous_result = {}
+      end
+    end
+
+    private def default_online_emit
+      {
+        mode: :file,
+        interval: 1,
+        path: 'tmp/coverage.json',
+      }
+    end
+
+    private def start_multipart_emit(option)
+      Thread.new do
+        @monitor.synchronize do
+          @previous_result = {}
+        end
+
+        loop do
+          sleep option[:interval]
+          current_result = peek_result
+
+          diff = {}
+          current_result.each do |path, path_coverage|
+            previous_path_coverage = @previous_result[path]
+
+            if previous_path_coverage.nil?
+              diff[path] = path_coverage
+            elsif previous_path_coverage[:lines].size != path_coverage[:lines].size
+              diff[path] = path_coverage
+            else
+              diff[path] = { lines: [] }
+
+              path_coverage[:lines].each_with_index do |count, index|
+                val = count ? count - previous_path_coverage[:lines][index] : nil
+
+                diff[path][:lines] << val
+              end
+            end
+          end
+
+          @monitor.synchronize do
+            @previous_result = current_result
+          end
+          File.write(option[:path], diff.to_json)
+          puts 'Akainaa: Coverage result emitted'
+        end
+      end
     end
   end
 

sample/Gemfile.lock

@@ -1,7 +1,7 @@
 PATH
   remote: ..
   specs:
-    akainaa (0.1.1)
+    akainaa (0.1.3)
 
 GEM
   remote: https://rubygems.org/

sample/config.ru

@@ -2,7 +2,13 @@
 
 require 'akainaa'
 
-Akainaa.start(project_dir: File.expand_path(__dir__))
+Akainaa.start(
+  project_dir: File.expand_path(__dir__),
+  online_emit: {
+    mode: :file,
+    interval: 10,
+  },
+)
 
 require_relative 'app'