1 files changed, 54 insertions, 0 deletions
diff --git a/jstests/core/always_true_false.js b/jstests/core/always_true_false.js
new file mode 100644
index 00000000000..0b32ac22a16
--- /dev/null
+++ b/jstests/core/always_true_false.js
@@ -0,0 +1,54 @@
+// Tests $alwaysTrue and $alwaysFalse behavior for match expressions.
+(function() {
+"use strict";
+
+const coll = db.always_true_false;
+coll.drop();
+
+assert.commandWorked(
+    coll.insert([{a: []}, {a: false}, {a: null}, {}, {a: false, b: 2}, {a: false, b: 1}]));
+
+// Check alwaysFalse.
+assert.eq(0, coll.find({$alwaysFalse: 1}).itcount());
+assert.eq(0, coll.find({$alwaysFalse: 1, a: false}).itcount());
+assert.eq(0, coll.find({$alwaysFalse: 1, b: 1}).itcount());
+
+// Check alwaysFalse with $and, $or.
+assert.eq(1, coll.find({$or: [{b: 1}, {$alwaysFalse: 1}]}).itcount());
+assert.eq(0, coll.find({$or: [{$alwaysFalse: 1}]}).itcount());
+assert.eq(0, coll.find({$or: [{$alwaysFalse: 1}, {$alwaysFalse: 1}]}).itcount());
+assert.eq(0, coll.find({$or: [{$alwaysFalse: 1}, {a: {$all: []}}, {$alwaysFalse: 1}]}).itcount());
+assert.eq(0, coll.find({$and: [{b: 1}, {$alwaysFalse: 1}]}).itcount());
+assert.eq(0, coll.find({$and: [{a: false}, {$alwaysFalse: 1}, {$alwaysFalse: 1}]}).itcount());
+
+// Check alwaysTrue.
+assert.eq(6, coll.find({$alwaysTrue: 1}).itcount());
+assert.eq(3, coll.find({$alwaysTrue: 1, a: false}).itcount());
+assert.eq(1, coll.find({$alwaysTrue: 1, b: 1}).itcount());
+
+// Check alwaysTrue with $and, $or.
+assert.eq(3, coll.find({$and: [{a: false}, {$alwaysTrue: 1}, {$alwaysTrue: 1}]}).itcount());
+assert.eq(0, coll.find({$and: [{a: false}, {$alwaysTrue: 1}, {$alwaysFalse: 1}]}).itcount());
+assert.eq(6, coll.find({$or: [{b: 1}, {$alwaysTrue: 1}]}).itcount());
+assert.eq(6, coll.find({$or: [{b: 1}, {$alwaysFalse: 1}, {$alwaysTrue: 1}]}).itcount());
+
+assert(coll.drop());
+
+// Check that a rooted-$or query with each clause false will not return any results.
+assert.commandWorked(coll.insert([{}, {}, {}]));
+const emptyOrError = assert.throws(() => coll.find({$or: []}).itcount());
+assert.eq(emptyOrError.code, ErrorCodes.BadValue);
+
+assert.eq(coll.find({$or: [{$alwaysFalse: 1}]}).itcount(), 0);
+assert.eq(coll.find({$or: [{a: {$all: []}}]}).itcount(), 0);
+assert.eq(coll.find({$or: [{$alwaysFalse: 1}, {$alwaysFalse: 1}]}).itcount(), 0);
+assert.eq(coll.find({$or: [{$alwaysFalse: 1}, {a: {$all: []}}, {$alwaysFalse: 1}]}).itcount(), 0);
+
+// Check failure cases.
+assert.commandFailedWithCode(db.runCommand({find: coll.getName(), filter: {$alwaysTrue: 0}}),
+                             ErrorCodes.FailedToParse);
+assert.commandFailedWithCode(db.runCommand({find: coll.getName(), filter: {$alwaysFalse: 0}}),
+                             ErrorCodes.FailedToParse);
+assert.commandFailedWithCode(db.runCommand({find: coll.getName(), filter: {a: {$alwaysFalse: 1}}}),
+                             ErrorCodes.BadValue);
+}());