SERVER-42080 `stdx::unordered_map<...>::at` must throw.

Added a test to check that this happens.

2 files changed, 51 insertions, 0 deletions

diff --git a/src/mongo/stdx/SConscript b/src/mongo/stdx/SConscript
index a51aa3423f4..f954fdf8398 100644
--- a/src/mongo/stdx/SConscript
+++ b/src/mongo/stdx/SConscript
@@ -13,3 +13,13 @@ env.Benchmark(
     ],
 )
 
+
+env.CppUnitTest(
+    target='stdx_test',
+    source=[
+        'unordered_map_test.cpp'
+    ],
+    LIBDEPS=[
+        '$BUILD_DIR/third_party/shim_abseil',
+    ],
+)
diff --git a/src/mongo/stdx/unordered_map_test.cpp b/src/mongo/stdx/unordered_map_test.cpp
new file mode 100644
index 00000000000..daeaea61358
--- /dev/null
+++ b/src/mongo/stdx/unordered_map_test.cpp
@@ -0,0 +1,41 @@
+/**
+ *    Copyright (C) 2019-present MongoDB, Inc.
+ *
+ *    This program is free software: you can redistribute it and/or modify
+ *    it under the terms of the Server Side Public License, version 1,
+ *    as published by MongoDB, Inc.
+ *
+ *    This program is distributed in the hope that it will be useful,
+ *    but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *    Server Side Public License for more details.
+ *
+ *    You should have received a copy of the Server Side Public License
+ *    along with this program. If not, see
+ *    <http://www.mongodb.com/licensing/server-side-public-license>.
+ *
+ *    As a special exception, the copyright holders give permission to link the
+ *    code of portions of this program with the OpenSSL library under certain
+ *    conditions as described in each individual source file and distribute
+ *    linked combinations including the program with the OpenSSL library. You
+ *    must comply with the Server Side Public License in all respects for
+ *    all of the code used other than as permitted herein. If you modify file(s)
+ *    with this exception, you may extend this exception to your version of the
+ *    file(s), but you are not obligated to do so. If you do not wish to do so,
+ *    delete this exception statement from your version. If you delete this
+ *    exception statement from all source files in the program, then also delete
+ *    it in the license file.
+ */
+
+#include "mongo/stdx/unordered_map.h"
+
+#include <stdexcept>
+
+#include "mongo/unittest/unittest.h"
+
+namespace {
+TEST(StdxUnorderedMapTest, atShouldThrow) {
+    mongo::stdx::unordered_map<int, int> m;
+    ASSERT_THROWS(m.at(42), std::out_of_range);
+}
+}  // namespace