Add comprehensive test cases for cuddAddFind.c with 87% line coverage

[Copilot]

Adds test coverage for src/cuddAddFind.c which had 0% coverage. Achieved 87% line coverage (60/69 lines) and 100% function coverage (4/4 functions).

Changes

• 42 new test cases covering:
  • Cudd_addFindMax: constant ADDs, multi-variable ADDs, cache hits, plus infinity early return, negative values, deep recursive structures
  • Cudd_addFindMin: constant ADDs, multi-variable ADDs, cache hits, minus infinity early return, negative values, deep recursive structures
  • Cudd_addIthBit: bit extraction for various values (0-255), T==E simplification path, cache hits, fractional truncation, high bit positions

Uncovered Lines

9 lines (13%) remain uncovered—all defensive error handling for memory exhaustion:

• Lines 211-215: NULL return from addDoIthBit
• Lines 278-279, 285-287: NULL returns from recursive calls and cuddUniqueInter

These paths require memory allocation failures mid-operation, which cannot be reliably triggered without mocking frameworks.

Example Test

TEST_CASE("Cudd_addFindMax - Complex ADD with multiple variables", "[cuddAddFind]") {
    DdManager *manager = Cudd_Init(0, 0, CUDD_UNIQUE_SLOTS, CUDD_CACHE_SLOTS, 0);
    
    DdNode *var0 = Cudd_addIthVar(manager, 0);
    DdNode *var1 = Cudd_addIthVar(manager, 1);
    Cudd_Ref(var0); Cudd_Ref(var1);
    
    // Build: if x0 then (if x1 then 100 else 5) else (if x1 then 7 else 1)
    DdNode *then_branch = Cudd_addIte(manager, var1, const100, const5);
    DdNode *else_branch = Cudd_addIte(manager, var1, const7, const1);
    DdNode *add = Cudd_addIte(manager, var0, then_branch, else_branch);
    
    DdNode *result = Cudd_addFindMax(manager, add);
    REQUIRE(Cudd_V(result) == 100.0);
    // cleanup...
}

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/cuddAddFind.c and target 90% coverage for the source file.

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