Simple tests for sub-set projections.

packages/minimongo/minimongo_tests.js

@@ -1069,6 +1069,55 @@ Tinytest.add("minimongo - fetch with fields", function (test) {
   });
 });
 
+Tinytest.add("minimongo - fetch with projection, subarrays", function (test) {
+  // Apparently projection of type 'foo.bar.x' for
+  // { foo: [ { bar: { x: 42 } }, { bar: { x: 3 } } ] }
+  // should return exactly this object. More precisely, arrays are considered as
+  // sets and are queried separately and then merged back to result set
+  var c = new LocalCollection();
+
+  // Insert a test object with two set fields
+  c.insert({
+    setA: [{
+      fieldA: 42,
+      fieldB: 33
+    }, {
+      fieldA: "the good",
+      fieldB: "the bad",
+      fieldC: "the ugly"
+    }],
+    setB: [{
+      anotherA: { },
+      anotherB: "meh"
+    }, {
+      anotherA: 1234,
+      anotherB: 431
+    }]
+  });
+
+  var equalNonStrict = function (a, b, desc) {
+    test.equal(EJSON.stringify(a), EJSON.stringify(b), desc);
+  };
+
+  var testForProjection = function (projection, expected) {
+    var fetched = c.find({}, { fields: projection }).fetch()[0];
+    equalNonStrict(fetched, expected, "failed sub-set projection: " +
+                                      JSON.stringify(projection));
+  };
+
+  testForProjection({ 'setA.fieldA': 1, 'setB.anotherB': 1, _id: 0 },
+                    {
+                      setA: [{ fieldA: 42 }, { fieldA: "the good" }],
+                      setB: [{ anotherB: "meh" }, { anotherB: 431 }]
+                    });
+
+  testForProjection({ 'setA.fieldA': 0, 'setB.anotherA': 0, _id: 0 },
+                    {
+                      setA: [{fieldB:33}, {fieldB:"the bad",fieldC:"the ugly"}],
+                      setB: [{ anotherB: "meh" }, { anotherB: 431 }]
+                    });
+});
+
 Tinytest.add("minimongo - observe ordered with projection", function (test) {
   // These tests are copy-paste from "minimongo -observe ordered",
   // slightly modified to test projection