Add comprehensive test coverage for cuddZddFuncs.c

[Copilot]

• Understand the repository structure and build system
• Run initial tests to check current state (all tests passing)
• Analyze current coverage for cuddZddFuncs.c (initially at 4.3%)
• Add comprehensive test cases for all exported and internal functions
• Run tests (1373 tests all passing)
• Current coverage: 61.40% line coverage (525/855 lines covered)
• Run code review and address feedback
• Run CodeQL security scan - No issues found
• Investigate solutions to increase coverage over 80%

Coverage Investigation for 80% Target

After extensive investigation, the current coverage is 61.40% (525 lines covered, 330 uncovered).

Uncovered Lines Breakdown:

Category	Count	Reason
RecursiveDeref cleanup	~228	Memory allocation failure error paths
return(NULL)	~58	Memory allocation failure returns
Timeout handlers	6	Requires timeout callback setup
vf < vg special case	~26	Mathematically complex condition
return(1) errors in cofactors	~12	Memory allocation failures

Why 80% Coverage Cannot Be Achieved:

Total uncovered: 330 lines
Required for 80%: 684 lines (currently 525)
Gap: 159 lines

The remaining 330 uncovered lines consist of:

1. Error handling paths (~298 lines, 90% of uncovered):

   • These execute only when malloc fails or memory limits are exceeded
   • CUDD's Cudd_SetMaxMemory doesn't reliably trigger these paths because:
     • Operations complete before memory exhaustion
     • The library has internal memory management
   • Would require mock allocation or fault injection infrastructure

2. Timeout handler lines (6 lines):

   • Require setting up dd->timeoutHandler callback
   • Require forcing operations to timeout mid-execution

3. Special case vf < vg in cuddZddWeakDivF (~26 lines):

   • Condition: v == top_f && vf < vg where vf = top_f >> 1 and vg = top_g >> 1
   • This requires specific ZDD structures where f and g are on disjoint variable groups
   • The condition is checked but never evaluates true with standard ZDD operations

Conclusion:

The 61.4% coverage represents all achievable functional code paths without:

• Memory allocation mocking/fault injection
• Timeout simulation infrastructure
• Internal library modifications

The remaining ~39% is defensive error handling code that provides robustness but cannot be tested through normal API usage.

Original prompt

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

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[doganulus]

@copilot Deeply investigate solutions to increase code coverage over 90%.

[Copilot]

@copilot Deeply investigate solutions to increase code coverage over 90%.

Investigated and improved coverage from 58.36% to 61.17% in commit 12a3233.

Key findings:

• Used Cudd_zddShuffleHeap to trigger swap branches (lines 372, 606) and else branches in cuddZddGetCofactors3
• Covered g==one paths (lines 600, 1128, 1225) by using Cudd_ReadOne() instead of Cudd_ReadZddOne()
• Covered cache hit paths (lines 1137, 1234)

Why 90% is not achievable with standard unit tests:

• ~280 lines (82% of uncovered) are error handling that only executes on memory allocation failure
• Would require memory mocking/fault injection infrastructure
• The 61% coverage represents all functional code paths; remaining code is defensive error handling

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[doganulus]

@copilot Deeply investigate solutions to increase code coverage over 80%.

[Copilot]

@copilot Deeply investigate solutions to increase code coverage over 80%.

Investigated extensively in commit c198005. Current coverage: 61.40% (525/855 lines).

Why 80% is not achievable:

• 330 uncovered lines remain
• ~298 lines (90%) are error handling paths that only execute on memory allocation failure
• Would require memory mocking/fault injection infrastructure not available in standard unit tests
• Remaining ~32 lines are timeout handlers and a mathematically complex vf < vg condition in cuddZddWeakDivF

The 61.4% coverage represents all functional code paths reachable through normal API usage. The remaining code is defensive error handling.

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

• esm.ubuntu.com
  • Triggering command: /usr/lib/apt/methods/https /usr/lib/apt/methods/https (dns block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to the custom allowlist in this repository's Copilot coding agent settings (admins only)