New API tested

storage/driver/boltdb_test.go

@@ -396,3 +396,50 @@ func fillBoltDB(t *testing.T, bdb *BoltDB) {
 		t.Fatal(err)
 	}
 }
+
+func TestApplySet(t *testing.T) {
+	cases := map[string]struct {
+		doc      bson.M
+		operator bson.M
+		want     bson.M
+	}{
+		"noop on empty": {},
+		"noop on full": {
+			doc:  bson.M{"hello": "world"},
+			want: bson.M{"hello": "world"},
+		},
+		"add new field on full": {
+			operator: bson.M{"hi": "mom"},
+			doc:      bson.M{"hello": "world"},
+			want:     bson.M{"hello": "world", "hi": "mom"},
+		},
+		"change only field on full": {
+			operator: bson.M{"hello": "lol jk not world"},
+			doc:      bson.M{"hello": "world"},
+			want:     bson.M{"hello": "lol jk not world"},
+		},
+		"set existing, nested field": {
+			operator: bson.M{"hello.world": "hi"},
+			doc:      bson.M{"hello": bson.M{"world": "not hi"}},
+			want:     bson.M{"hello": bson.M{"world": "hi"}},
+		},
+		"add to existing, nested field": {
+			operator: bson.M{"hello.notworld": "hi"},
+			doc:      bson.M{"hello": bson.M{"world": "not hi"}},
+			want:     bson.M{"hello": bson.M{"world": "not hi", "notworld": "hi"}},
+		},
+	}
+
+	for name, d := range cases {
+		c := d
+		t.Run(name, func(t *testing.T) {
+			out, err := applySet(c.doc, c.operator)
+			if err != nil {
+				t.Fatal(err)
+			}
+			if fmt.Sprint(out) != fmt.Sprint(c.want) {
+				t.Fatalf("(%+v, %+v) => want \n%+v\n, got \n%+v", c.doc, c.operator, c.want, out)
+			}
+		})
+	}
+}