Test InputStream.transferTo() (#1526)

* Test InputStream.transferTo()

* Don't crash on Java 8

okio/src/jvmMain/kotlin/okio/RealBufferedSource.kt

@@ -185,9 +185,6 @@ internal actual class RealBufferedSource actual constructor(
             if (read == -1L) break
           }
           count += buffer.size
-          if (count < 0) {
-            count = Long.MAX_VALUE
-          }
           buffer.writeTo(out)
         }
         return count

okio/src/jvmTest/kotlin/okio/BufferedSourceTest.kt

@@ -15,6 +15,11 @@
  */
 package okio
 
+import assertk.assertThat
+import assertk.assertions.isEqualTo
+import assertk.assertions.isTrue
+import java.io.ByteArrayInputStream
+import java.io.ByteArrayOutputStream
 import java.io.EOFException
 import java.nio.ByteBuffer
 import java.nio.charset.Charset
@@ -991,6 +996,24 @@ class BufferedSourceTest(
     }
   }
 
+  @Test
+  fun inputStreamTransferTo() {
+    try {
+      ByteArrayInputStream(byteArrayOf(1)).transferTo(ByteArrayOutputStream())
+    } catch (e: NoSuchMethodError) {
+      return // This JDK doesn't have transferTo(). Skip this test.
+    }
+
+    val data = "a".repeat(SEGMENT_SIZE * 3 + 1)
+    sink.writeUtf8(data)
+    sink.emit()
+    val inputStream = source.inputStream()
+    val outputStream = ByteArrayOutputStream()
+    inputStream.transferTo(outputStream)
+    assertThat(source.exhausted()).isTrue()
+    assertThat(outputStream.toByteArray().toUtf8String()).isEqualTo(data)
+  }
+
   @Test
   fun longHexString() {
     assertLongHexString("8000000000000000", -0x7fffffffffffffffL - 1L)