IntegroDiff tests fail with spvals/SparseArrays error during Zygote differentiation

[ChrisRackauckas-Claude]

Summary

The IntegroDiff tests (7 test items) fail during Zygote differentiation through Cubature/Integrals.jl with an UndefVarError: spvals not defined error. This appears to be related to SparseArrays not being properly loaded in the Zygote differentiation path through Cubature.

Error

ERROR: UndefVarError: `spvals` not defined

The error occurs during backward pass through Zygote when differentiating through integral computations that use Cubature.

Affected Tests

All 7 IntegroDiff tests in test/IDE_tests.jl:

• IntegroDiff Example 1 -- 1D
• IntegroDiff Example 2 -- 1D (integral bound not including whole spatial domain)
• IntegroDiff Example 3 -- 1D (integral term inside the chain rule)
• IntegroDiff Example 4 -- 2D (integral w.r.t. x)
• IntegroDiff Example 5 -- 2D (integral w.r.t. y)
• IntegroDiff Example 6 -- 2D (integral w.r.t. x with separate kernel function)
• IntegroDiff Example 7 -- System of 2D integro-differential equation

Current Status

Tests are temporarily skipped in PR #1013 to unblock CI.

Related

This is likely related to the same Zygote/Cubature/Integrals.jl compatibility issues affecting QuadratureTraining methods.

References

• PR Fix compatibility with ModelingToolkit 11, Symbolics 7, and SymbolicUtils 4 #1013 where tests were skipped
• Similar issues may exist in Integrals.jl or Cubature.jl repos