Merge pull request #725 from JetBrains/refactor-junit-executor

A tiny refactoring: use groupBy

Author: nikpachoo

executors/src/main/kotlin/JUnitExecutors.kt

@@ -22,14 +22,7 @@ class JUnitExecutors {
           jUnitCore.run(request)
         }
         System.setOut(standardOutput)
-        val groupedTestResults = HashMap<String, MutableList<TestRunInfo>>()
-        for (testRunInfo in output) {
-          if (!groupedTestResults.containsKey(testRunInfo.className)) {
-            groupedTestResults[testRunInfo.className] = ArrayList()
-          }
-          groupedTestResults[testRunInfo.className]?.add(testRunInfo)
-        }
-        print(mapper.writeValueAsString(groupedTestResults))
+        standardOutput.print(mapper.writeValueAsString(output.groupBy({ it.className }, { it })))
       }
       catch (e: Exception) {
         System.setOut(standardOutput)