SERVER-15816 explained upserts against an empty collection shouldn't try to create a collection

1 files changed, 36 insertions, 0 deletions

diff --git a/jstests/core/explain_upsert.js b/jstests/core/explain_upsert.js
new file mode 100644
index 00000000000..41282e9bf51
--- /dev/null
+++ b/jstests/core/explain_upsert.js
@@ -0,0 +1,36 @@
+// Test explain for {upsert: true} updates.
+
+var t = db.jstests_explain_upsert;
+t.drop();
+
+var explain;
+
+// Explained upsert against an empty collection should succeed and be a no-op.
+explain = db.runCommand({
+    explain: {
+        update: t.getName(),
+        updates: [
+            {q: {a: 1}, u: {a: 1}, upsert: true}
+        ]
+    }
+});
+assert.commandWorked(explain);
+
+// Collection should still not exist.
+assert.eq(0, t.count());
+assert(!t.drop());
+
+// Add a document to the collection.
+t.insert({a: 3});
+
+// An explained upsert against a non-empty collection should also succeed as a no-op.
+explain = db.runCommand({
+    explain: {
+        update: t.getName(),
+        updates: [
+            {q: {a: 1}, u: {a: 1}, upsert: true}
+        ]
+    }
+});
+assert.commandWorked(explain);
+assert.eq(1, t.count());