write-flow-tests

Writing Python Flow Tests

Guidelines for writing new end-to-end Python flow tests in tests/pytests/.

Framework

Tests use the RLTest framework. The typical pattern is:

1. Create an index with env.expect('FT.CREATE', ...).ok()
2. Load data with conn.execute_command('HSET', ...)
3. Assert query results with env.cmd(...) or env.expect(...)

Finding where to add tests

• Search existing test files in tests/pytests/ for related functionality using Grep (function names, command names, feature names).
• Determine whether an existing test can be extended or a new test is needed.
• Look at nearby tests in the same file for style and patterns specific to that file.

Test function signature

• Accept env as a parameter when the test works with the default environment (dialect 2 on CI):

  def testMyFeature(env):
  

• Only create a custom Env() when you need specific settings that differ from the default, such as:
  • protocol=3 (to access res['warning'] dicts)
  • DEFAULT_DIALECT 1 (to test legacy behavior)
  • Other non-default moduleArgs
• Always document why a custom Env() is needed if it's not obvious.

Cluster considerations

• Add @skip(cluster=True) to tests that don't exercise cluster-specific behavior. This avoids redundant test runs.
• If a test does need to run in cluster mode, use {hash_tag} key prefixes (e.g., {doc}:1) to ensure keys land on the same shard.

Index creation

• Use env.expect('FT.CREATE', ...).ok() for creating indexes — not conn.execute_command('FT.CREATE', ...).
• Reserve conn (getConnectionByEnv(env)) for key-write commands like HSET, DEL, etc.

Waiting for index

• Data inserted before FT.CREATE: Background indexing is activated. Call waitForIndex(env, 'idx') after FT.CREATE to wait for the backfill to complete before querying.
• Data inserted after FT.CREATE: Each HSET/JSON.SET is immediately acknowledged by the index — no waitForIndex needed.
• Do not call waitForIndex right after FT.CREATE with no pre-existing data — there is nothing to wait for.

Assertions

• Compare the full result when the response is deterministic and small:

  # Good — full result comparison
  res = env.cmd('FT.SEARCH', 'idx', '@t:{al*}', 'NOCONTENT')
  env.assertEqual(res, [1, 'doc1'])
  
  # Good — empty result
  res = env.cmd('FT.SEARCH', 'idx', '@t:{a*}', 'NOCONTENT')
  env.assertEqual(res, [0])
  

• Add message=res when the assertion checks only part of the result (e.g., assertGreaterEqual), so failures show the actual response:

  env.assertGreaterEqual(res[0], 9, message=res)
  

• Use env.expect(...).error().contains('...') for error-path tests.
• Use env.assertContains(...) for checking substrings in responses (e.g., warning messages, explain output).

Deprecated commands

• Do not use FT.ADD — use HSET via conn.execute_command('HSET', ...) instead.
• FT.ADD does not work in cluster mode and is deprecated.

Test structure

• Include a docstring explaining what code path or behavior the test exercises.
• Keep tests focused — one test per code path or behavior.
• Restore global config changes (e.g., MAXPREFIXEXPANSIONS) at the end of the test.