1 files changed, 67 insertions, 0 deletions
diff --git a/jstests/core/query/count/count6.js b/jstests/core/query/count/count6.js
new file mode 100644
index 00000000000..78735c89c26
--- /dev/null
+++ b/jstests/core/query/count/count6.js
@@ -0,0 +1,67 @@
+// Some correctness checks for fast and normal count modes, including with skip and limit.
+//
+// @tags: [requires_fastcount]
+
+t = db.jstests_count6;
+
+function checkCountForObject(obj) {
+    t.drop();
+    t.createIndex({b: 1, a: 1});
+
+    function checkCounts(query, expected) {
+        assert.eq(expected, t.count(query), "A1");
+        assert.eq(expected, t.find(query).skip(0).limit(0).count(true), "A2");
+        // Check proper counts with various skip and limit specs.
+        for (var skip = 1; skip <= 2; ++skip) {
+            for (var limit = 1; limit <= 2; ++limit) {
+                assert.eq(Math.max(expected - skip, 0), t.find(query).skip(skip).count(true), "B1");
+                assert.eq(Math.min(expected, limit), t.find(query).limit(limit).count(true), "B2");
+                assert.eq(Math.min(Math.max(expected - skip, 0), limit),
+                          t.find(query).skip(skip).limit(limit).count(true),
+                          "B4");
+
+                // Check limit(x) = limit(-x)
+                assert.eq(t.find(query).limit(limit).count(true),
+                          t.find(query).limit(-limit).count(true),
+                          "C1");
+                assert.eq(t.find(query).skip(skip).limit(limit).count(true),
+                          t.find(query).skip(skip).limit(-limit).count(true),
+                          "C2");
+            }
+        }
+
+        // Check limit(0) has no effect
+        assert.eq(expected, t.find(query).limit(0).count(true), "D1");
+        assert.eq(
+            Math.max(expected - skip, 0), t.find(query).skip(skip).limit(0).count(true), "D2");
+        assert.eq(
+            expected, t.getDB().runCommand({count: t.getName(), query: query, limit: 0}).n, "D3");
+        assert.eq(Math.max(expected - skip, 0),
+                  t.getDB().runCommand({count: t.getName(), query: query, limit: 0, skip: skip}).n,
+                  "D4");
+    }
+
+    for (var i = 0; i < 5; ++i) {
+        checkCounts({a: obj.a, b: obj.b}, i);
+        checkCounts({b: obj.b, a: obj.a}, i);
+        t.insert(obj);
+    }
+
+    t.insert({a: true, b: true});
+    t.insert({a: true, b: 1});
+    t.insert({a: false, b: 1});
+    t.insert({a: false, b: true});
+    t.insert({a: false, b: false});
+
+    checkCounts({a: obj.a, b: obj.b}, i);
+    checkCounts({b: obj.b, a: obj.a}, i);
+
+    // Check with no query
+    checkCounts({}, 10);
+}
+
+// Check fast count mode.
+checkCountForObject({a: true, b: false});
+
+// Check normal count mode.
+checkCountForObject({a: 1, b: 0});