Index: common-build.xml
===================================================================
--- common-build.xml	(revision 1035418)
+++ common-build.xml	(working copy)
@@ -65,6 +65,7 @@
   </condition>
   <property name="tests.multiplier" value="1" />
   <property name="tests.codec" value="random" />
+  <property name="tests.randomCodecPerField" value="true"/>
   <property name="tests.locale" value="random" />
   <property name="tests.timezone" value="random" />
   <property name="tests.directory" value="random" />
Index: src/test/org/apache/lucene/util/LuceneTestCase.java
===================================================================
--- src/test/org/apache/lucene/util/LuceneTestCase.java	(revision 1035418)
+++ src/test/org/apache/lucene/util/LuceneTestCase.java	(working copy)
@@ -35,6 +35,8 @@
 import org.apache.lucene.index.codecs.preflex.PreFlexCodec;
 import org.apache.lucene.index.codecs.preflexrw.PreFlexRWCodec;
 import org.apache.lucene.index.codecs.pulsing.PulsingCodec;
+import org.apache.lucene.index.codecs.simpletext.SimpleTextCodec;
+import org.apache.lucene.index.codecs.standard.StandardCodec;
 import org.apache.lucene.search.BooleanQuery;
 import org.apache.lucene.search.FieldCache;
 import org.apache.lucene.search.FieldCache.CacheEntry;
@@ -69,6 +71,7 @@
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collections;
+import java.util.HashMap;
 import java.util.IdentityHashMap;
 import java.util.Iterator;
 import java.util.List;
@@ -142,6 +145,8 @@
   // tests)
   /** Gets the codec to run tests with. */
   static final String TEST_CODEC = System.getProperty("tests.codec", "random");
+  /** Get if a random codec per field should be used */ // only use random per field if no explicit codec is set
+  static final boolean TEST_RAMDOM_CODEC_PER_FIELD = "random".equals(TEST_CODEC) && Boolean.parseBoolean(System.getProperty("tests.randomCodecPerField", "true"));
   /** Gets the locale to run tests with */
   static final String TEST_LOCALE = System.getProperty("tests.locale", "random");
   /** Gets the timezone to run tests with */
@@ -316,6 +321,7 @@
     timeZone = TEST_TIMEZONE.equals("random") ? randomTimeZone(random) : TimeZone.getTimeZone(TEST_TIMEZONE);
     TimeZone.setDefault(timeZone);
     testsFailed = false;
+    randomCodecProvider = new RandomCodecProvider(random);
   }
   
   @AfterClass
@@ -336,11 +342,11 @@
       }
     stores = null;
     // if tests failed, report some information back
-    if (testsFailed)
+    if (testsFailed) {
       System.out.println("NOTE: test params are: codec=" + codec + 
         ", locale=" + locale + 
-        ", timezone=" + (timeZone == null ? "(null)" : timeZone.getID()));
-    if (testsFailed) {
+        ", timezone=" + (timeZone == null ? "(null)" : timeZone.getID()) + 
+       (TEST_RAMDOM_CODEC_PER_FIELD?", "+randomCodecProvider.toString():""));
       System.err.println("NOTE: all tests run in this JVM:");
       System.err.println(Arrays.toString(testClassesRun.toArray()));
     }
@@ -636,7 +642,9 @@
       logmp.setCalibrateSizeByDeletes(r.nextBoolean());
       logmp.setMergeFactor(_TestUtil.nextInt(r, 2, 20));
     }
-    
+    if (TEST_RAMDOM_CODEC_PER_FIELD) {
+      c.setCodecProvider(randomCodecProvider);
+    }
     c.setReaderPooling(r.nextBoolean());
     c.setReaderTermsIndexDivisor(_TestUtil.nextInt(r, 1, 4));
     return c;
@@ -838,6 +846,8 @@
   // seed for individual test methods, changed in @before
   private long seed;
   
+  protected static CodecProvider randomCodecProvider;
+  
   private static final Random seedRand = new Random();
   protected static final Random random = new Random();
 
@@ -901,4 +911,45 @@
       }
     }
   }
+  
+  static class RandomCodecProvider extends CodecProvider {
+
+    private final Codec[] codecs;
+    private final Map<String, String> perFieldMap = new HashMap<String, String>();
+    private final Random random;
+
+    RandomCodecProvider(Random random) {
+      this.codecs = new Codec[] { new StandardCodec(), new SimpleTextCodec(),
+          new MockSepCodec(), new PulsingCodec(1 + random.nextInt(10)),
+          new MockVariableIntBlockCodec(1 + random.nextInt(10)),
+          new MockFixedIntBlockCodec(1 + random.nextInt(10)) };
+      for (int i = 0; i < codecs.length; i++) {
+        super.register(codecs[i]);
+      }
+      // register preflex to support reading of old indexes
+      this.register(new PreFlexCodec());
+      this.random = random;
+    }
+
+    @Override
+    public synchronized String getFieldCodec(String name) {
+      if (!perFieldMap.containsKey(name)) { // select a codec at random
+        setFieldCodec(name, codecs[random.nextInt(codecs.length)].name);
+      }
+      return super.getFieldCodec(name);
+    }
+
+    @Override
+    public synchronized void setFieldCodec(String field, String codec) {
+      if (!perFieldMap.containsKey(field)) {
+        perFieldMap.put(field, codec);
+      }
+      super.setFieldCodec(field, codec);
+    }
+
+    @Override
+    public String toString() {
+      return "RandomCodecProvider [perFieldMap=" + perFieldMap + "]";
+    }
+  }
 }