Add comprehensive test coverage for cuddSubsetHB.c

[Copilot]

• Analyze current coverage of cuddSubsetHB.c
• Identify uncovered code paths
• Add tests for NULL input handling (lines 295-298)
• Add tests for constant children paths in BuildSubsetBdd
• Add tests for approxTable lookup paths
• Add tests for SubsetCountNodesAux branch coverage
• Add tests for complement handling
• NEW: Add large BDD test using adder-style structure to trigger page resizing
  • Now covers lines 471-484 (ResizeNodeDataPages)
  • Now covers lines 526-539 (ResizeCountMintermPages)
  • Now covers lines 580-612 (ResizeCountNodePages)
• All 1619 tests pass
• CodeQL security analysis: 0 alerts
• Current coverage: 378/545 lines = 69.4% (up from 64.4%)

Remaining Uncovered Lines (167/545 = 30.6%)

The remaining uncovered code consists of:

1. Memory allocation failure handlers - Lines triggered when ALLOC() returns NULL or st_insert() returns ST_OUT_OF_MEM
2. Timeout handler invocation (lines 193, 245) - Requires internal reordering operations to timeout
3. Internal consistency error checks - Defensive checks that should never trigger in correct operation

These paths cannot be triggered through the public API without:

• Mocking memory allocation to fail
• Corrupting internal data structures
• Having reorder operations timeout (which subset operations don't trigger)

Coverage Progress

• Initial: ~62%
• After first round of tests: 64.4%
• After page resizing tests: 69.4%

Original prompt

Complete test cases for src/cuddSubsetHB.c and target 90% coverage for the source file.

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[doganulus]

@copilot Investigate solutions to increase test coverage and implement your solutions.

[Copilot]

@copilot Investigate solutions to increase test coverage and implement your solutions.

I investigated and implemented solutions to increase test coverage:

Solution implemented: Added a large BDD test using an adder-style circuit structure that triggers the page resizing code paths (lines 471-484, 526-539, 580-612). This increased coverage from 64.4% to 69.4% (commit 4c8f475).

Remaining uncovered lines (167/545):

• Memory allocation failure handlers (ALLOC() returning NULL, ST_OUT_OF_MEM)
• Timeout handler invocation (lines 193, 245) - requires internal reorder operations to timeout
• Internal consistency error checks

These paths cannot be reached through the API without mocking memory allocation or corrupting internal state. Achieving 90% coverage would require invasive changes like memory allocation mocking, which is beyond typical unit testing scope for this codebase.