Add comprehensive test cases for cuddSubsetSP.c

[Copilot]

Adds test coverage for the shortest paths subset extraction heuristic (cuddSubsetSP.c), which had 0% coverage.

Coverage achieved

• Line coverage: 70.6% (404/572 lines)
• Function coverage: 81.8% (9/11 functions)

Test cases added

• Cudd_SubsetShortPaths / Cudd_SupersetShortPaths: Constants, single variables, AND/OR/XOR/ITE/XNOR structures, complemented functions
• Parameter variations: numVars=0 default, thresholds 1-1000+, hardlimit flag (0/1)
• Edge cases: Path length computation, cache hits, node reuse, threshold exceeds numVars

Why not 80%

The uncovered 168 lines (~29%) are:

• ResizeNodeDistPages / ResizeQueuePages — require >262K unique nodes to trigger page reallocation
• Memory error handlers — require ST_OUT_OF_MEM conditions
• Internal error handlers — unreachable in normal operation

// Example test structure
TEST_CASE("Cudd_SubsetShortPaths - AND function", "[cuddSubsetSP]") {
    DdManager *manager = Cudd_Init(0, 0, CUDD_UNIQUE_SLOTS, CUDD_CACHE_SLOTS, 0);
    DdNode *x = Cudd_bddNewVar(manager);
    DdNode *y = Cudd_bddNewVar(manager);
    DdNode *f = Cudd_bddAnd(manager, x, y);
    
    DdNode *result = Cudd_SubsetShortPaths(manager, f, 2, 2, 1);
    REQUIRE(Cudd_bddLeq(manager, result, f));  // Result is subset of f
}

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)

Original prompt

Complete test cases for src/cuddSubsetSP.c to achieve 80% code coverage.

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💡 You can make Copilot smarter by setting up custom instructions, customizing its development environment and configuring Model Context Protocol (MCP) servers. Learn more Copilot coding agent tips in the docs.

[coveralls]

Pull Request Test Coverage Report for Build 19699488655

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 2 unchanged lines in 1 file lost coverage.
• Overall coverage increased (+1.4%) to 32.381%

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Files with Coverage Reduction	New Missed Lines	%
src/cuddReorder.c	2	37.84%

Totals
Change from base Build 19697583343:	1.4%
Covered Lines:	9586
Relevant Lines:	29604

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💛 - Coveralls