add test comments

1 files changed, 18 insertions, 1 deletions

diff --git a/jstests/capped7.js b/jstests/capped7.js
index ecb689e23c6..693828da85f 100644
--- a/jstests/capped7.js
+++ b/jstests/capped7.js
@@ -1,3 +1,5 @@
+// Test NamespaceDetails::emptyCappedCollection via 'emptycapped' command
+
 Random.setRandomSeed();
 
 db.capped7.drop();
@@ -8,6 +10,10 @@ var ten = new Array( 11 ).toString().replace( /,/g, "-" );
 
 count = 0;
 
+/**
+ * Insert new documents until the capped collection loops and the document
+ * count doesn't increase on insert.
+ */
 function insertUntilFull() {
 count = tzz.count();
     var j = 0;
@@ -23,21 +29,27 @@ while( 1 ) {
 
 insertUntilFull();
 
+// oldCount == count before empty
 oldCount = count;
 
 assert.eq.automsg( "11", "tzz.stats().numExtents" );
+
+// oldSize == size before empty
 var oldSize = tzz.stats().storageSize;
 
 assert.commandWorked( db._dbCommand( { emptycapped: "capped7" } ) );
 
+// check that collection storage parameters are the same after empty
 assert.eq.automsg( "11", "tzz.stats().numExtents" );
 assert.eq.automsg( "oldSize", "tzz.stats().storageSize" );
 
+// check that the collection is empty after empty
 assert.eq.automsg( "0", "tzz.find().itcount()" );
 assert.eq.automsg( "0", "tzz.count()" );
 
+// check that we can reuse the empty collection, inserting as many documents
+// as we were able to the first time through.
 insertUntilFull();
-
 assert.eq.automsg( "oldCount", "count" );
 assert.eq.automsg( "oldCount", "tzz.find().itcount()" );
 assert.eq.automsg( "oldCount", "tzz.count()" );
@@ -47,12 +59,16 @@ var oldSize = tzz.stats().storageSize;
 
 assert.commandWorked( db._dbCommand( { emptycapped: "capped7" } ) );
 
+// check that the collection storage parameters are unchanged after another empty
 assert.eq.automsg( "11", "tzz.stats().numExtents" );
 assert.eq.automsg( "oldSize", "tzz.stats().storageSize" );
 
+// insert an arbitrary number of documents
 var total = Random.randInt( 2000 );
 for( var j = 1; j <= total; ++j ) {
     tzz.save( {i:ten,j:j} );
+    // occasionally check that only the oldest documents are removed to make room
+    // for the newest documents
     if ( Random.rand() > 0.95 ) {
         assert.automsg( "j >= tzz.count()" );
         assert.eq.automsg( "tzz.count()", "tzz.find().itcount()" );
@@ -62,6 +78,7 @@ for( var j = 1; j <= total; ++j ) {
         while( c.hasNext() ) {
             assert.eq.automsg( "c.next().j", "k--" );
         }
+        // check the same thing with a reverse iterator as well
         var c = tzz.find().sort( {$natural:1} );
         assert.automsg( "c.hasNext()" );
         while( c.hasNext() ) {