fixes #467 this is a useful feature for some folks with complex deployments

lib/coverband/adapters/base.rb

@@ -140,7 +140,9 @@ def merge_expanded_data(new_expanded, old_expanded)
 
       # TODO: This should only be 2 cases get our dup / not dups aligned
       def array_add(latest, original)
-        if Coverband.configuration.use_oneshot_lines_coverage
+        if latest.empty? && original.empty?
+          []
+        elsif Coverband.configuration.use_oneshot_lines_coverage
           latest.map!.with_index { |v, i| ((v + original[i] >= 1) ? 1 : 0) if v && original[i] }
         elsif Coverband.configuration.simulate_oneshot_lines_coverage
           latest.map.with_index { |v, i| ((v + original[i] >= 1) ? 1 : 0) if v && original[i] }

lib/coverband/adapters/redis_store.rb

@@ -72,6 +72,15 @@ def raw_store
         @redis
       end
 
+      def file_count
+        data = redis.get type_base_key(Coverband::RUNTIME_TYPE)
+        JSON.parse(data).keys.length
+      end
+
+      def cached_file_count
+        @cached_file_count ||= file_count
+      end
+
       private
 
       attr_reader :redis

lib/coverband/reporters/json_report.rb

@@ -5,13 +5,16 @@
 module Coverband
   module Reporters
     class JSONReport < Base
-      attr_accessor :filtered_report_files, :options, :page, :as_report, :store, :filename, :base_path
+      attr_accessor :filtered_report_files, :options, :page, :as_report, :store, :filename, :base_path, :line_coverage,
+        :for_merged_report
 
       def initialize(store, options = {})
         self.options = options
         self.page = options.fetch(:page) { nil }
         self.filename = options.fetch(:filename) { nil }
         self.as_report = options.fetch(:as_report) { false }
+        self.line_coverage = options.fetch(:line_coverage) { false }
+        self.for_merged_report = options.fetch(:for_merged_report) { false }
         self.base_path = options.fetch(:base_path) { "./" }
         self.store = store
 
@@ -28,6 +31,33 @@ def report
         report_as_json
       end
 
+      def merge_reports(first_report, second_report, options = {})
+        merged_data = {}
+        merged_data[Coverband::RUNTIME_TYPE.to_s] = Coverband::Adapters::Base.new.send(
+          :merge_reports,
+          first_report[Coverband::RUNTIME_TYPE.to_s],
+          second_report[Coverband::RUNTIME_TYPE.to_s],
+          {skip_expansion: true}
+        )
+        if first_report[Coverband::EAGER_TYPE.to_s] && second_report[Coverband::EAGER_TYPE.to_s]
+          merged_data[Coverband::EAGER_TYPE.to_s] = Coverband::Adapters::Base.new.send(
+            :merge_reports,
+            first_report[Coverband::EAGER_TYPE.to_s],
+            second_report[Coverband::EAGER_TYPE.to_s],
+            {skip_expansion: true}
+          )
+        end
+        if first_report[Coverband::MERGED_TYPE.to_s] && second_report[Coverband::MERGED_TYPE.to_s]
+          merged_data[Coverband::MERGED_TYPE.to_s] = Coverband::Adapters::Base.new.send(
+            :merge_reports,
+            first_report[Coverband::MERGED_TYPE.to_s],
+            second_report[Coverband::MERGED_TYPE.to_s],
+            {skip_expansion: true}
+          )
+        end
+        merged_data
+      end
+
       private
 
       def coverage_css_class(covered_percent)
@@ -43,6 +73,8 @@ def coverage_css_class(covered_percent)
       end
 
       def report_as_json
+        return filtered_report_files.to_json if for_merged_report
+
         result = Coverband::Utils::Results.new(filtered_report_files)
         source_files = result.source_files
 
@@ -97,7 +129,7 @@ def coverage_totals(source_files)
       def coverage_files(result, source_files)
         source_files.each_with_object({}) do |source_file, hash|
           runtime_coverage = result.file_with_type(source_file, Coverband::RUNTIME_TYPE)&.covered_lines_count || 0
-          hash[source_file.short_name] = {
+          data = {
             filename: source_file.filename,
             hash: Digest::SHA1.hexdigest(source_file.filename),
             never_loaded: source_file.never_loaded,
@@ -109,6 +141,8 @@ def coverage_files(result, source_files)
             covered_percent: source_file.covered_percent,
             covered_strength: source_file.covered_strength
           }
+          data[:coverage] = source_file.coverage if line_coverage
+          hash[source_file.short_name] = data
         end
       end
     end

lib/coverband/utils/dead_methods.rb

@@ -1,4 +1,4 @@
-# frozen_string_literal: ntrue
+# frozen_string_literal: true
 
 require "coverband/utils/method_definition_scanner"
 

lib/coverband/utils/tasks.rb

@@ -33,8 +33,12 @@
     require "coverband/utils/results"
     require "coverband/reporters/json_report"
 
-    report = Coverband::Reporters::JSONReport.new(Coverband.configuration.store).report
-    File.write("coverage/coverage.json", report)
+    report = Coverband::Reporters::JSONReport.new(Coverband.configuration.store, {
+      for_merged_report: !!ENV["FOR_MERGED_REPORT"],
+      line_coverage: true
+    }).report
+    `mkdir -p coverage`
+    File.write("coverage/coverage.json.#{Time.now.to_f}", report)
   end
 
   ###
@@ -68,6 +72,39 @@
     SimpleCov::Formatter::HTMLFormatter.new.format(result)
   end
 
+  ####
+  # This task can aggregate multiple coverage files into a single coverage report
+  # * `FOR_MERGED_REPORT=true bundle exec rake coverband:coverage_json` to generate the JSON files
+  # * collect all the files over time in some system or as artifacts in CI, then run...
+  # * `bundle exec rake coverband:aggregate_coverage` to merge the files
+  # * the output will include a timestamp of when it was output...
+  ####
+  task :aggregate_coverage do |task, args|
+    require "coverband/utils/result"
+    require "coverband/utils/file_list"
+    require "coverband/utils/source_file"
+    require "coverband/utils/lines_classifier"
+    require "coverband/utils/results"
+    require "coverband/reporters/json_report"
+
+    directory = "./coverage"
+    pattern = "coverage.json*"
+
+    # Use Dir.glob to find files matching the pattern in the specified directory
+    files = Dir.glob(File.join(directory, pattern))
+
+    report = {}
+    files.each do |file|
+      data = JSON.parse(File.read(file))
+      report = if report.empty?
+        data
+      else
+        Coverband::Reporters::JSONReport.new(Coverband.configuration.store).merge_reports(report, data)
+      end
+    end
+    File.write("coverage/coverage_merged.json.#{Time.now.to_f}", report.to_json)
+  end
+
   desc "Run a simple rack app to report Coverband code coverage"
   task :coverage_server do
     if Rake::Task.task_defined?("environment")

test/coverband/reporters/base_test.rb

@@ -75,7 +75,6 @@ def setup
     roots = ['/base/[0-9]*/', '/base/78/app/']
 
     Coverband.configuration.stubs(:all_root_paths).returns(roots)
-    lines_hit = [1, 3, 6]
     store.stubs(:merged_coverage).returns(coverage)
     File.expects(:exist?).at_least_once
       .with('/base/[0-9]*/app/controllers/dashboard_controller.rb')

test/coverband/reporters/json_test.rb

@@ -45,4 +45,15 @@ def setup
       assert_equal parsed["files"][file].keys, expected_keys
     end
   end
+
+  test "supports merging" do
+    @store.send(:save_report, basic_coverage)
+    first_report = JSON.parse(Coverband::Reporters::JSONReport.new(@store, for_merged_report: true).report)
+
+    @store.send(:save_report, increased_basic_coverage)
+    second_report = JSON.parse(Coverband::Reporters::JSONReport.new(@store, for_merged_report: true).report)
+    data = Coverband::Reporters::JSONReport.new(@store).merge_reports(first_report, second_report)
+    assert_equal data[Coverband::RUNTIME_TYPE.to_s]["app_path/dog.rb"]["data"], [0, 4, 10]
+    assert_equal data[Coverband::MERGED_TYPE.to_s]["app_path/dog.rb"]["data"], [0, 4, 10]
+  end
 end

test/test_helper.rb

@@ -125,6 +125,10 @@ def basic_coverage
   {"app_path/dog.rb" => example_line}
 end
 
+def increased_basic_coverage
+  {"app_path/dog.rb" => [0, 2, 6]}
+end
+
 def basic_coverage_full_path
   {basic_coverage_file_full_path => example_line}
 end