autotuner: add unit tests for parse_flow_variables and parse_tunable_variables

[rohithsiddi]

Problem

Two helper functions in tools/AutoTuner/src/autotuner/utils.py had explicit TODO: Tests. comments with no accompanying tests:

• parse_flow_variables (line 186) — parses environment variables from Tcl scripts and a generated vars.tcl file
• parse_tunable_variables (line 221) — reads variables.yaml and returns the set of variables marked as tunable

Note: parse_flow_variables was the original validation approach in parse_config before being superseded by parse_tunable_variables in 4458cacb. The function remains defined with an explicit TODO and is tested here for completeness.

These functions are on the critical path: parse_tunable_variables is called by parse_config on every tuning run to validate which variables are allowed.

Changes

• tools/AutoTuner/test/test_utils.py — new test file covering both functions
• flow/test/test_autotuner.sh — invoke the new tests before the smoke tests

Test coverage

parse_flow_variables

Test	What it covers
test_parse_flow_variables_from_scripts_and_vars_tcl	Happy path: reads scripts/*.tcl and vars.tcl, extracts env vars via regex, normalises to uppercase, verifies make vars call signature
test_parse_flow_variables_exits_when_make_fails	make returns non-zero → prints [ERROR TUN-0018] and exits
test_parse_flow_variables_exits_when_vars_tcl_is_missing	make succeeds but vars.tcl is absent → prints [ERROR TUN-0019] and exits

parse_tunable_variables

Test	What it covers
test_parse_tunable_variables_returns_only_tunable_keys	Returns only keys with tunable=1; excludes tunable=0 and keys with no tunable field

subprocess.run and yaml.safe_load are mocked at the module level so no Makefile or real variables.yaml is required. A real temporary filesystem is used for the Tcl file parsing to exercise the actual glob/regex/file-read path.

[gemini-code-assist]

Code Review

This pull request introduces unit tests for the AutoTuner utility and the rule file generation logic. It adds tools/AutoTuner/test/test_utils.py, which is integrated into the test_autotuner.sh script, and a new test suite flow/test/test_genRuleFile.py. Review feedback highlights that test_genRuleFile.py is currently not invoked by any test scripts and should be integrated into the CI pipeline. Additionally, a workaround in the wildcard matching test points to a logic bug in genRuleFile.py that should be addressed directly.