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/import/create_session_test.rs

@@ -0,0 +1,30 @@
+use crate::support::create_import_session_command;
+use std::sync::Arc;
+
+use uuid::Uuid;
+
+use domain::testing::InMemoryStore;
+
+use crate::support::TestContextBuilder;
+use application::import::create_session;
+use application::import::deps::CreateSessionDeps;
+
+#[tokio::test]
+async fn creates_session_with_parsed_file() {
+    let sessions = InMemoryStore::new();
+    let b = TestContextBuilder::new();
+
+    let deps = CreateSessionDeps {
+        import_session: Arc::clone(&sessions) as _,
+        document_parser: b.document_parser.clone(),
+    };
+
+    let result = create_session::execute(
+        &deps,
+        create_import_session_command(Uuid::new_v4(), b"col1\nval1"),
+    )
+    .await
+    .unwrap();
+
+    assert!(!result.columns.is_empty());
+}