HADOOP-2927. Fix TestDU to acurately calculate the expected file size. Contributed by shv.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/core/trunk@644603 13f79535-47bb-0310-9956-ffa450edef68

CHANGES.txt

@@ -455,6 +455,9 @@ Trunk (unreleased changes)
     HADOOP-3161. Fix FIleUtil.HardLink.getLinkCount on Mac OS. (nigel
     via omalley)
 
+    HADOOP-2927. Fix TestDU to acurately calculate the expected file size.
+    (shv via nigel)
+
 Release 0.16.2 - 2008-04-02
 
   BUG FIXES

src/test/org/apache/hadoop/fs/TestDU.java

@@ -53,32 +53,27 @@ public class TestDU extends TestCase {
     file.getFD().sync();
     file.close();
   }
-  
-  /*
-   * Find a number that is a multiple of the block size in this file system
-   */
-  private int getBlockSize() throws IOException, InterruptedException {
-    File file = new File(DU_DIR, "small");
-    createFile(file, 128); // this is an arbitrary number. It has to be big enough for the filesystem to report
-                           // any usage at all. For instance, NFS reports 0 blocks if the file is <= 64 bytes
-
-    Thread.sleep(5000); // let the metadata updater catch up
-
-    DU du = new DU(file, 0);
-    return (int) du.getUsed();
-  }
 
+  /**
+   * Verify that du returns expected used space for a file.
+   * We assume here that if a file system crates a file of size 
+   * that is a multiple of the block size in this file system,
+   * then the used size for the file will be exactly that size.
+   * This is true for most file systems.
+   * 
+   * @throws IOException
+   * @throws InterruptedException
+   */
   public void testDU() throws IOException, InterruptedException {
-    int blockSize = getBlockSize();
-
+    int writtenSize = 32*1024;   // writing 32K
     File file = new File(DU_DIR, "data");
-    createFile(file, 2 * blockSize);
+    createFile(file, writtenSize);
 
     Thread.sleep(5000); // let the metadata updater catch up
     
     DU du = new DU(file, 0);
-    long size = du.getUsed();
+    long duSize = du.getUsed();
 
-    assertEquals(2 * blockSize, size);
+    assertEquals(writtenSize, duSize);
   }
 }