Append to existing log file if it exists instead of rewriting it

lib/miss_cleo/tests_to_files_map_logger.rb

@@ -15,7 +15,11 @@ def add_to_log(test_file_and_line, lines_run_before, lines_run_after, templates)
     end
 
     def export_logs
-      File.open(file_name, 'w') { |f| f.write JSON.dump logs }
+      if File.exists?(file_name)
+        file = JSON.parse(File.read(file_name))
+        @logs += file
+      end
+      File.open(file_name, 'w') { |f| f.write JSON.dump @logs }
     end
 
     private

lib/miss_cleo/version.rb

@@ -1,3 +1,3 @@
 module MissCleo
-  VERSION = "0.4.7"
+  VERSION = "0.4.8"
 end

spec/tests_to_files_map_logger_spec.rb

@@ -32,5 +32,15 @@
       expect(File.exists?(file_name)).to be
       FileUtils.rm(file_name)
     end
+
+    it "appends to an existing log" do
+      file_name = 'test.json'
+      File.open(file_name, 'w') { |f| f.write JSON.dump [["hello"]] }
+      logger = described_class.new(file_name)
+      logger.export_logs
+      lines = File.read(file_name)
+      expect(lines).to eq("[[\"hello\"]]")
+      FileUtils.rm(file_name)
+    end
   end
 end