Minor: make test output less verbose

(cherry picked from commit 919c099)

Author: ilya-g

libraries/stdlib/test/ExceptionJVMTest.kt

@@ -6,6 +6,7 @@ import test.collections.assertArrayNotSameButEquals
 import org.junit.Test  as test
 import java.io.PrintWriter
 import java.io.*
+import java.nio.charset.Charset
 
 class ExceptionJVMTest {
 
@@ -24,7 +25,7 @@ class ExceptionJVMTest {
         val buffer = StringWriter()
         val writer = PrintWriter(buffer)
         t.printStackTrace(writer)
-        println(buffer)
+        comparePrintedThrowableResult(t, buffer.buffer)
     }
 
     fun assertPrintStackTraceStream(t: Throwable) {
@@ -40,7 +41,17 @@ class ExceptionJVMTest {
         }
 
         val bytes = assertNotNull(byteBuffer.toByteArray())
-        assertTrue(bytes.size > 10)
+        val content = bytes.toString(Charset.defaultCharset())
+        comparePrintedThrowableResult(t, content)
+    }
+
+    private fun comparePrintedThrowableResult(throwable: Throwable, printedThrowable: CharSequence) {
+        val stackTrace = throwable.stackTrace
+        val lines = printedThrowable.lines()
+        assertEquals(throwable.toString(), lines[0])
+        stackTrace.forEachIndexed { index, frame ->
+            assertTrue(lines.any { frame.toString() in it }, "frame at index $index is not found in the printed message")
+        }
     }
 
     @test fun changeStackTrace() {

libraries/stdlib/test/concurrent/TimerTest.kt

@@ -15,12 +15,12 @@ class TimerTest {
 
         val task = timer.scheduleAtFixedRate(1000, 100) {
             val current = counter.incrementAndGet()
-            println("Timer fired at $current")
+            // println("Timer fired at $current")
         }
         Thread.sleep(1500)
         task.cancel()
 
         val value = counter.get()
-        assertTrue(value > 4, "current counter is $value")
+        assertTrue(value > 4, "Expected to fire at least 4 times, but was $value")
     }
 }

libraries/stdlib/test/io/Files.kt

@@ -157,7 +157,7 @@ class FilesTest {
 
         fun assertFailsRelativeTo(file: File, base: File) {
             val e = assertFailsWith<IllegalArgumentException>("file: $file, base: $base") { file.relativeTo(base) }
-            println(e.message)
+//            println(e.message)
         }
 
         val allFiles = listOf(absolute, relative) + if (isBackslashSeparator) listOf(networkShare1, networkShare2) else emptyList()