test: move application tests to tests/

test_support/test_helpers -> tests/support; watched_at unified w/ domain test_watched_at (2024-03-15).
Kept inline: users::diary_filter tests (feed_sort_to_direction_all_variants, paged_user_filter_builds_correctly) - pub(super) helpers in private module.
Dropped stale never-compiled users/tests/get_users.rs (old execute signature).

crates/application/tests/users/authorize_admin_test.rs

@@ -0,0 +1,91 @@
+use crate::support::TestContextBuilder;
+use crate::support::register_command;
+use std::sync::Arc;
+
+use domain::models::UserRole;
+use domain::testing::InMemoryStore;
+
+use application::{
+    auth::{commands::RegisterCommand, deps::RegisterDeps, register},
+    users::{authorize_admin, deps::AuthorizeAdminDeps},
+};
+
+async fn register_user(
+    b: &TestContextBuilder,
+    email: &str,
+    username: &str,
+    role: UserRole,
+) -> domain::models::User {
+    let reg_deps = RegisterDeps {
+        user: b.user_repo.clone(),
+        password_hasher: b.password_hasher.clone(),
+        config: b.config.clone(),
+    };
+    register::execute(
+        &reg_deps,
+        RegisterCommand {
+            role,
+            ..register_command(email, username)
+        },
+    )
+    .await
+    .unwrap();
+
+    b.user_repo
+        .find_by_email(&domain::value_objects::Email::new(email.into()).unwrap())
+        .await
+        .unwrap()
+        .unwrap()
+}
+
+#[tokio::test]
+async fn authorize_admin_is_true_for_an_admin_user() {
+    let users = InMemoryStore::new();
+    let b = TestContextBuilder::new().with_users(Arc::clone(&users) as _);
+    let user = register_user(&b, "admin@example.com", "admin_user", UserRole::Admin).await;
+
+    let deps = AuthorizeAdminDeps {
+        user: b.user_repo.clone(),
+    };
+    let result = authorize_admin::execute(&deps, user.id().value())
+        .await
+        .unwrap();
+
+    assert_eq!(result, Some(true));
+}
+
+#[tokio::test]
+async fn authorize_admin_is_false_for_a_regular_user() {
+    let users = InMemoryStore::new();
+    let b = TestContextBuilder::new().with_users(Arc::clone(&users) as _);
+    let user = register_user(
+        &b,
+        "standard@example.com",
+        "standard_user",
+        UserRole::Standard,
+    )
+    .await;
+
+    let deps = AuthorizeAdminDeps {
+        user: b.user_repo.clone(),
+    };
+    let result = authorize_admin::execute(&deps, user.id().value())
+        .await
+        .unwrap();
+
+    assert_eq!(result, Some(false));
+}
+
+#[tokio::test]
+async fn authorize_admin_is_not_found_for_unknown_user() {
+    let b = TestContextBuilder::new();
+
+    let deps = AuthorizeAdminDeps {
+        user: b.user_repo.clone(),
+    };
+    let result = authorize_admin::execute(&deps, uuid::Uuid::new_v4())
+        .await
+        .unwrap();
+
+    assert_eq!(result, None);
+}