Index: lucene/src/test/org/apache/lucene/index/TestIndexReader.java
===================================================================
--- lucene/src/test/org/apache/lucene/index/TestIndexReader.java	(revision 1045172)
+++ lucene/src/test/org/apache/lucene/index/TestIndexReader.java	(working copy)
@@ -1850,5 +1850,16 @@
     }
     dir.close();
   }
-  
+
+  // LUCENE-2812
+  public void testIndexExists() throws Exception {
+    Directory dir = newDirectory();
+    IndexWriter writer = new IndexWriter(dir, newIndexWriterConfig(TEST_VERSION_CURRENT, new MockAnalyzer()));
+    writer.addDocument(new Document());
+    writer.prepareCommit();
+    assertFalse(IndexReader.indexExists(dir));
+    writer.close();
+    assertTrue(IndexReader.indexExists(dir));
+    dir.close();
+  }
 }
Index: lucene/src/java/org/apache/lucene/index/IndexReader.java
===================================================================
--- lucene/src/java/org/apache/lucene/index/IndexReader.java	(revision 1045172)
+++ lucene/src/java/org/apache/lucene/index/IndexReader.java	(working copy)
@@ -835,13 +835,17 @@
 
   /**
    * Returns <code>true</code> if an index exists at the specified directory.
-   * If the directory does not exist or if there is no index in it.
    * @param  directory the directory to check for an index
    * @return <code>true</code> if an index exists; <code>false</code> otherwise
    * @throws IOException if there is a problem with accessing the index
    */
   public static boolean indexExists(Directory directory) throws IOException {
-    return SegmentInfos.getCurrentSegmentGeneration(directory) != -1;
+    try {
+      new SegmentInfos().read(directory);
+      return true;
+    } catch (IOException ioe) {
+      return false;
+    }
   }
 
   /** Returns the number of documents in this index. */