util: add tests for list_of_keys.

The main case we wanted to cover, std::unordered_map with multiple
entries, requires a non-ideal test function, because it isn't
deterministic by design.

util/tests/list-of-keys-test.cc

@@ -0,0 +1,46 @@
+#include <tuple>
+
+#include <catch2/catch_test_macros.hpp>
+
+#include "util.h"
+
+TEST_CASE("std::unordered_map with multiple entries", "[list-of-keys]")
+{
+    std::unordered_map<std::string_view, int> map = {
+        {"first", 0},
+        {"second", 0},
+    };
+
+    auto s = list_of_keys(map);
+    auto rv = s == "first, second" || s == "second, first";
+    REQUIRE(rv == true);
+}
+
+TEST_CASE("std::unordered_map with single entry", "[list-of-keys]")
+{
+    std::unordered_map<std::string_view, int> map = {
+        {"first", 0},
+    };
+
+    REQUIRE(list_of_keys(map) == "first");
+}
+
+TEST_CASE("std::vector with multiple entries", "[list-of-keys]")
+{
+    std::vector<std::string> vec = {
+        "first",
+        "second",
+        "third",
+    };
+
+    REQUIRE(list_of_keys(vec) == "first, second, third");
+}
+
+TEST_CASE("std::vector with single entry", "[list-of-keys]")
+{
+    std::vector<std::string> vec = {
+        "first",
+    };
+
+    REQUIRE(list_of_keys(vec) == "first");
+}

util/tests/meson.build

@@ -4,5 +4,8 @@ test_util_lib = static_library('test-util', test_util_src, dependencies: [utilit
 copy_test = executable('copy-test', 'copy-test.cc', link_with: [test_util_lib], dependencies: [thread_dep, utilities])
 test('copy-test', copy_test)
 
+list_of_keys_test = executable('list-of-keys-test', 'list-of-keys-test.cc', dependencies: [utilities, catch2])
+test('list-of-keys-test', list_of_keys_test)
+
 fixed_test = executable('fixed-test', 'fixed-test.cc', dependencies: [utilities, catch2])
 test('fixed-test', fixed_test)