Add small test for service builder

.config/nextest.toml

@@ -1,7 +1,9 @@
+# Test that test groups are assigned correctly using:
+# `cargo nextest show-config test-groups`
 [test-groups]
 # Mocks of static methods need to run sequentially. This test group is for tests that mock AppService's static methods.
 app-service-static-mock = { max-threads = 1 }
 
 [[profile.default.overrides]]
-filter = 'test(service::registry::tests::)'
+filter = 'test(#service::registry::tests::*) | test(#service::tests::*)'
 test-group = "app-service-static-mock"

src/service/mod.rs

@@ -72,3 +72,41 @@ where
 
     async fn build(self, context: &AppContext<A::State>) -> anyhow::Result<S>;
 }
+
+#[cfg(test)]
+mod tests {
+    use crate::app::MockTestApp;
+    use crate::app_context::MockAppContext;
+    use crate::service::{AppServiceBuilder, MockAppService};
+    use async_trait::async_trait;
+    use rstest::rstest;
+
+    struct TestAppServiceBuilder;
+    #[async_trait]
+    impl AppServiceBuilder<MockTestApp, MockAppService<MockTestApp>> for TestAppServiceBuilder {
+        async fn build(
+            self,
+            _context: &MockAppContext<()>,
+        ) -> anyhow::Result<MockAppService<MockTestApp>> {
+            Ok(MockAppService::default())
+        }
+    }
+
+    #[rstest]
+    #[case(true)]
+    #[case(false)]
+    fn builder_enabled(#[case] service_enabled: bool) {
+        // Arrange
+        let mut context = MockAppContext::default();
+        context.expect_clone().returning(MockAppContext::default);
+
+        let enabled_ctx = MockAppService::<MockTestApp>::enabled_context();
+        enabled_ctx.expect().returning(move |_| service_enabled);
+
+        // Act
+        let builder = TestAppServiceBuilder;
+
+        // Assert
+        assert_eq!(builder.enabled(&context), service_enabled);
+    }
+}