Add removeAll() helper to C++ tests (#2461)

examples/cpp/CMakeLists.txt

@@ -19,6 +19,6 @@ FetchContent_Declare(
 
 FetchContent_MakeAvailable(Catch2 cpprealm)
 
-add_executable(examples examples.cpp define-object-model.cpp authentication.cpp)
+add_executable(examples testHelpers.hpp examples.cpp define-object-model.cpp authentication.cpp testHelpersTests.cpp)
 target_link_libraries(examples PRIVATE Catch2::Catch2WithMain)
 target_link_libraries(examples PRIVATE cpprealm)

examples/cpp/examples.cpp

@@ -3,6 +3,7 @@
 #include <string>
 #include <thread>
 #include <future>
+#include "testHelpers.hpp"
 
 // :snippet-start: includes
 #include <cpprealm/sdk.hpp>
@@ -68,9 +69,7 @@ TEST_CASE("first test case", "[test]") {
     });
     // :snippet-end:
     // Clean up after the test
-    realm.write([&realm, &dog] {
-        realm.remove(dog);
-    });
+    removeAll(realm);
 }
 
 TEST_CASE("create a dog", "[write]") {

examples/cpp/testHelpers.hpp

@@ -0,0 +1,25 @@
+#ifndef testHelpers_h
+#define testHelpers_h
+
+#include <cpprealm/sdk.hpp>
+
+/**
+    Removes all objects of all types from a realm.
+ */
+template<typename... Ts>
+void removeAll(realm::db<Ts...> &realm) {
+    // Iterate over the template parameter pack (Ts...)
+    ([&realm] {
+        // For each T in realm, fetch all objects of type T
+        auto objects = realm.template objects<Ts>();
+        realm.write([&realm, &objects] {
+            // Iterate over the results to delete each object (at time of writing,
+            // realm.removeAll() and realm.remove(collection) do not exist)
+            for (auto object : objects) {
+                realm.template remove(object);
+            }
+        });
+    }(), ...); // This is called a "fold expression"
+}
+
+#endif

examples/cpp/testHelpersTests.cpp

@@ -0,0 +1,51 @@
+#include <catch2/catch_test_macros.hpp>
+
+#include "testHelpers.hpp"
+
+struct SyncDog : realm::object {
+    realm::persisted<realm::uuid> _id;
+    realm::persisted<std::string> name;
+    realm::persisted<int> age;
+
+    static constexpr auto schema = realm::schema("SyncDog",
+        realm::property<&SyncDog::_id, true>("_id"),
+        realm::property<&SyncDog::name>("name"),
+        realm::property<&SyncDog::age>("age"));
+};
+
+struct Dog : realm::object {
+    realm::persisted<std::string> name;
+    realm::persisted<int> age;
+
+    static constexpr auto schema = realm::schema("Dog",
+        realm::property<&Dog::name>("name"),
+        realm::property<&Dog::age>("age"));
+};
+
+struct Person : realm::object {
+    realm::persisted<std::string> _id;
+    realm::persisted<std::string> name;
+    realm::persisted<int> age;
+    realm::persisted<std::optional<Dog>> dog;
+    static constexpr auto schema = realm::schema("Person",
+        realm::property<&Person::_id, true>("_id"), // primary key
+        realm::property<&Person::name>("name"),
+        realm::property<&Person::age>("age"),
+        realm::property<&Person::dog>("dog"));
+};
+
+TEST_CASE("removeAll removes all", "[meta]") {
+    auto realm = realm::open<Person, Dog, SyncDog>();
+    realm.write([&realm] {
+        realm.add(Dog { .name = "Rex", .age = 1 });
+        realm.add(Person { ._id = "123", .name = "Ali", .age = 1 });
+        realm.add(SyncDog { ._id = realm::uuid{}, .name = "Cyber Rex", .age = 1 });
+    });
+    REQUIRE(realm.objects<Dog>().size() > 0);
+    REQUIRE(realm.objects<Person>().size() > 0);
+    REQUIRE(realm.objects<SyncDog>().size() > 0);
+    removeAll(realm);
+    REQUIRE(realm.objects<Dog>().size() == 0);
+    REQUIRE(realm.objects<Person>().size() == 0);
+    REQUIRE(realm.objects<SyncDog>().size() == 0);
+}