Speed up test suite via fixture scope optimization and slow test markers

[Copilot]

Many tests unnecessarily open a new .NET Database connection per test function despite being read-only or sharing the same underlying database file. Database opens via pythonnet are expensive.

Fixture scope optimizations

• TestDatabase.db: Function-scoped → class-scoped, eliminating ~10 redundant DB opens. Extracted test_close to its own TestDatabaseClose class to avoid closing the shared connection.
• TestBaseQuery: Added class-scoped _db fixture so the Database opens once instead of per-test (~11 opens saved, including 8 parametrized test_by_muid cases). base_query remains function-scoped for mutable state isolation.
• test_scenarios.py: Grouped two read-only tests into TestScenarioReadOnly with a class-scoped db on session_sirius_db. Saves 2 file copies + 2 DB opens + fixes connection leaks.
• test_create_existing_model_raises_error: sirius_db → session_sirius_db (read-only check, no copy needed).

Slow test markers

• All simulation runner tests marked @pytest.mark.slow.
• Added -m not slow to default pytest addopts in pyproject.toml, so slow tests are skipped by default when running locally. CI workflows are unaffected since they pass explicit -m flags on the command line, which override addopts.

Original prompt

The test suite is very slow. Explore opportunities to speed it up.

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[ryan-kipawa]

@copilot

You marked some tests as slow. Adjust pyproject.toml pytest configuration such that it does not run slow tests by default locally. Do not update the github action - there they should run.

After running the tests locally, these were the 50 slowest tests.

===================================================== slowest 50 durations ====================================================== 
51.25s call     tests/test_simulation_runner.py::test_mike_engine_run_flood
42.30s call     tests/test_simulation_runner.py::test_mike_engine_run_swmm
20.63s call     tests/test_simulation_runner.py::test_mike_engine_run_epanet
18.75s call     tests/test_simulation_runner.py::test_mike_engine_run_1d
14.36s call     tests/database/test_table_generation.py::TestTableGeneration::test_generated_code_can_be_imported_and_used        
12.80s call     tests/database/test_database.py::TestDatabaseOpen::test_open_existing_model
9.72s call     tests/test_tools.py::test_import_tool
7.17s call     tests/test_tools.py::test_interpolate_tool
6.87s call     tests/test_tools.py::test_catch_slope_len_tool
6.10s call     tests/test_tools.py::test_connect_repair_tool
6.01s setup    tests/database/test_queries.py::TestInsertQuery::test_insert
5.80s call     tests/test_tools.py::test_topology_repair_tool
5.71s setup    tests/database/test_database.py::TestDatabase::test_is_open
5.41s call     tests/test_scenarios.py::test_api_create_and_activate_scenario
5.11s setup    tests/database/test_queries.py::TestDeleteQuery::test_safety_check
5.07s setup    tests/database/test_queries.py::TestUpdateQuery::test_safety_check
4.95s setup    tests/database/test_tables.py::TestBaseTable::test_name
3.17s call     tests/database/test_database.py::TestDatabase::test_top_level_imports
2.79s call     tests/database/test_database.py::TestDatabaseCreate::test_create_new_model
2.66s call     tests/database/test_database.py::TestDatabaseCreate::test_import_epanet
2.41s call     tests/database/test_database.py::TestDatabaseCreate::test_import_swmm
2.10s setup    tests/database/test_table_generation.py::TestTableGeneration::test_generate_single_table_class
2.03s setup    tests/database/test_table_generation.py::TestTableGeneration::test_generated_code_can_be_imported_and_used
1.95s setup    tests/database/test_table_generation.py::TestTableGeneration::test_generate_all_tables
0.68s call     tests/database/test_database.py::TestDatabaseClose::test_close
0.67s call     tests/database/test_table_generation.py::TestTableGeneration::test_generate_all_tables
0.63s call     tests/database/test_queries.py::TestBaseQuery::test_base_query_error_if_not_open
0.63s setup    tests/database/test_queries.py::TestBaseQuery::test_where_clause
0.62s setup    tests/test_scenarios.py::TestScenarioReadOnly::test_api_access_scenarios_and_alternatives
0.61s setup    tests/database/test_queries.py::TestSelectQuery::test_select_all_columns
0.56s setup    tests/database/test_table_collection.py::TestBaseTableCollection::test_initialize_tables
0.54s setup    tests/database/test_queries.py::TestUpdateQuery::test_update_computation_begin_with_string

[Copilot]

@copilot

You marked some tests as slow. Adjust pyproject.toml pytest configuration such that it does not run slow tests by default locally. Do not update the github action - there they should run....

Added -m not slow to pyproject.toml addopts in 0160235. Running pytest locally now skips slow tests by default. CI workflows are unchanged — they all pass explicit -m flags which override the addopts default, so slow tests still run there.