SERVER-43749 Modernize mapReduce tests in core

1 files changed, 104 insertions, 0 deletions

diff --git a/jstests/core/mr_reduce.js b/jstests/core/mr_reduce.js
new file mode 100644
index 00000000000..aded1cf471d
--- /dev/null
+++ b/jstests/core/mr_reduce.js
@@ -0,0 +1,104 @@
+// Tests the 'reduce' output mode for mapReduce.
+// Cannot implicitly shard accessed collections because of following errmsg: Cannot output to a
+// non-sharded collection because sharded collection exists already.
+// @tags: [
+//   assumes_unsharded_collection,
+//   # mapReduce does not support afterClusterTime.
+//   does_not_support_causal_consistency,
+//   does_not_support_stepdowns,
+//   uses_map_reduce_with_temp_collections,
+// ]
+(function() {
+"use strict";
+(function() {
+const source = db.mr_reduce;
+source.drop();
+
+assert.commandWorked(source.insert({_id: 1, a: [1, 2]}));
+assert.commandWorked(source.insert({_id: 2, a: [2, 3]}));
+assert.commandWorked(source.insert({_id: 3, a: [3, 4]}));
+
+const out = db.mr_reduce_out;
+const outName = out.getName();
+out.drop();
+
+const map = function() {
+    for (let i = 0; i < this.a.length; i++)
+        emit(this.a[i], 1);
+};
+const reduce = function(k, vs) {
+    return Array.sum(vs);
+};
+
+assert.commandWorked(source.mapReduce(map, reduce, {out: outName}));
+
+let expected = [{_id: 1, value: 1}, {_id: 2, value: 2}, {_id: 3, value: 2}, {_id: 4, value: 1}];
+assert.docEq(expected, out.find().sort({_id: 1}).toArray());
+
+assert.commandWorked(source.insert({_id: 4, a: [4, 5]}));
+// Insert something that should be unaltered by the mapReduce into the output collection.
+assert.commandWorked(out.insert({_id: 10, value: 5}));
+assert.commandWorked(
+    source.mapReduce(map, reduce, {out: {reduce: outName}, query: {_id: {$gt: 3}}}));
+
+expected = [
+    {_id: 1, value: 1},
+    {_id: 2, value: 2},
+    {_id: 3, value: 2},
+    {_id: 4, value: 2},
+    {_id: 5, value: 1},
+    {_id: 10, value: 5}
+];
+assert.docEq(expected, out.find().sort({_id: 1}).toArray());
+
+assert.commandWorked(source.insert({_id: 5, a: [5, 6]}));
+// Insert something that should be unaltered by the mapReduce into the output collection.
+assert.commandWorked(out.insert({_id: 20, value: 10}));
+assert.commandWorked(
+    source.mapReduce(map, reduce, {out: {reduce: outName}, query: {_id: {$gt: 4}}}));
+
+expected = [
+    {_id: 1, value: 1},
+    {_id: 2, value: 2},
+    {_id: 3, value: 2},
+    {_id: 4, value: 2},
+    {_id: 5, value: 2},
+    {_id: 6, value: 1},
+    {_id: 10, value: 5},
+    {_id: 20, value: 10}
+];
+assert.docEq(expected, out.find().sort({_id: 1}).toArray());
+}());
+(function() {
+const source = db.mr_reduce;
+source.drop();
+
+assert.commandWorked(source.insert({_id: 1, x: 1}));
+assert.commandWorked(source.insert({_id: 2, x: 1}));
+assert.commandWorked(source.insert({_id: 3, x: 2}));
+
+const out = db.mr_reduce_out;
+const outName = out.getName();
+out.drop();
+
+const map = function() {
+    emit(this.x, 1);
+};
+const reduce = function(k, v) {
+    return Array.sum(v);
+};
+
+assert.commandWorked(
+    source.mapReduce(map, reduce, {out: {reduce: outName}, query: {_id: {$gt: 0}}}));
+
+assert.eq(2, out.findOne({_id: 1}).value);
+assert.eq(1, out.findOne({_id: 2}).value);
+
+assert.commandWorked(source.insert({_id: 4, x: 2}));
+assert.commandWorked(
+    source.mapReduce(map, reduce, {out: {reduce: outName}, query: {_id: {$gt: 3}}}));
+
+assert.eq(2, out.findOne({_id: 1}).value);
+assert.eq(2, out.findOne({_id: 2}).value);
+}());
+}());