From 4078f293fbdee9ee60601cff43748f455ef9960b Mon Sep 17 00:00:00 2001
From: Oscar Dowson <o.dowson@gmail.com>
Date: Wed, 9 Sep 2026 11:40:55 +1200
Subject: [PATCH] [Utilities] fix deleting variables and constraints in
 MockOptimizer

---
 src/Utilities/mockoptimizer.jl       | 24 ++++++++++--------
 test/Utilities/test_mockoptimizer.jl | 38 ++++++++++++++++++++++++++++
 2 files changed, 51 insertions(+), 11 deletions(-)

diff --git a/src/Utilities/mockoptimizer.jl b/src/Utilities/mockoptimizer.jl
index 401df2b21e..00c833b04e 100644
--- a/src/Utilities/mockoptimizer.jl
+++ b/src/Utilities/mockoptimizer.jl
@@ -865,15 +865,15 @@ end
 function MOI.delete(mock::MockOptimizer, index::MOI.VariableIndex)
     if !mock.delete_allowed
         throw(MOI.DeleteNotAllowed(index))
-    end
-    if !MOI.is_valid(mock, index)
+    elseif !MOI.is_valid(mock, index)
         # The index thrown by `mock.inner_model` would be xored
         throw(MOI.InvalidIndex(index))
     end
-    MOI.delete(mock.inner_model, xor_index(index))
-    delete!(mock.variable_primal, index)
-    delete!(mock.callback_variable_primal, index)
-    delete!(mock.variable_basis_status, index)
+    xored = xor_index(index)
+    MOI.delete(mock.inner_model, xored)
+    delete!(mock.variable_primal, xored)
+    delete!(mock.callback_variable_primal, xored)
+    delete!(mock.variable_basis_status, xored)
     return
 end
 
@@ -885,8 +885,9 @@ function MOI.delete(mock::MockOptimizer, indices::Vector{MOI.VariableIndex})
         # The index thrown by `mock.inner_model` would be xored
         MOI.throw_if_not_valid(mock, index)
     end
-    MOI.delete(mock.inner_model, xor_index.(indices))
-    for index in indices
+    xored = xor_index.(indices)
+    MOI.delete(mock.inner_model, xored)
+    for index in xored
         delete!(mock.variable_primal, index)
         delete!(mock.callback_variable_primal, index)
         delete!(mock.variable_basis_status, index)
@@ -902,9 +903,10 @@ function MOI.delete(mock::MockOptimizer, index::MOI.ConstraintIndex)
         # The index thrown by `mock.inner_model` would be xored
         throw(MOI.InvalidIndex(index))
     end
-    MOI.delete(mock.inner_model, xor_index(index))
-    delete!(mock.constraint_dual, index)
-    delete!(mock.constraint_basis_status, index)
+    xored = xor_index(index)
+    MOI.delete(mock.inner_model, xored)
+    delete!(mock.constraint_dual, xored)
+    delete!(mock.constraint_basis_status, xored)
     return
 end
 
diff --git a/test/Utilities/test_mockoptimizer.jl b/test/Utilities/test_mockoptimizer.jl
index 8cb2b56786..c2550d3a12 100644
--- a/test/Utilities/test_mockoptimizer.jl
+++ b/test/Utilities/test_mockoptimizer.jl
@@ -307,6 +307,44 @@ function test_empty_constructor()
     return
 end
 
+function test_delete_mock_variable()
+    model = MOI.Utilities.MockOptimizer(MOI.Utilities.Model{Float64}())
+    x = MOI.add_variables(model, 3)
+    MOI.set.(model, MOI.VariablePrimal(), x, [1.0, 2.0, 3.0])
+    MOI.delete(model, x[2])
+    @test length(model.variable_primal) == 2
+    @test haskey(model.variable_primal, MOI.Utilities.xor_index(x[1]))
+    @test !haskey(model.variable_primal, MOI.Utilities.xor_index(x[2]))
+    @test haskey(model.variable_primal, MOI.Utilities.xor_index(x[3]))
+    return
+end
+
+function test_delete_mock_variable_vector()
+    model = MOI.Utilities.MockOptimizer(MOI.Utilities.Model{Float64}())
+    x = MOI.add_variables(model, 3)
+    MOI.set.(model, MOI.VariablePrimal(), x, [1.0, 2.0, 3.0])
+    MOI.delete(model, x[1:2])
+    @test length(model.variable_primal) == 1
+    @test !haskey(model.variable_primal, MOI.Utilities.xor_index(x[1]))
+    @test !haskey(model.variable_primal, MOI.Utilities.xor_index(x[2]))
+    @test haskey(model.variable_primal, MOI.Utilities.xor_index(x[3]))
+    return
+end
+
+function test_delete_mock_constraint()
+    model = MOI.Utilities.MockOptimizer(MOI.Utilities.Model{Float64}())
+    x = MOI.add_variables(model, 3)
+    c = MOI.add_constraint.(model, x, MOI.EqualTo(1.0))
+    @test isempty(model.constraint_dual)
+    MOI.set.(model, MOI.ConstraintDual(), c, [1.0, 2.0, 3.0])
+    MOI.delete(model, c[2])
+    @test length(model.constraint_dual) == 2
+    @test haskey(model.constraint_dual, MOI.Utilities.xor_index(c[1]))
+    @test !haskey(model.constraint_dual, MOI.Utilities.xor_index(c[2]))
+    @test haskey(model.constraint_dual, MOI.Utilities.xor_index(c[3]))
+    return
+end
+
 end  # module
 
 TestMockOptimizer.runtests()