Update

Author: odow

src/MathOptInterface.jl

@@ -393,14 +393,10 @@ const IndexMap = Utilities.IndexMap
 import PrecompileTools
 
 PrecompileTools.@setup_workload begin
-    optimizer =
-        () -> Utilities.MockOptimizer(
-            Utilities.UniversalFallback(Utilities.Model{Float64}()),
-        )
     PrecompileTools.@compile_workload begin
         model = Utilities.CachingOptimizer(
             Utilities.UniversalFallback(Utilities.Model{Float64}()),
-            instantiate(optimizer; with_bridge_type = Float64),
+            instantiate(Utilities.MockOptimizer; with_bridge_type = Float64),
         )
         set(model, Silent(), true)
         x = add_variables(model, 3)

src/Utilities/mockoptimizer.jl

@@ -131,6 +131,11 @@ function MockOptimizer(
     )
 end
 
+function MockOptimizer(::Type{T} = Float64; kwargs...) where {T}
+    inner = UniversalFallback(Utilities.Model{T}())
+    return MockOptimizer(inner, T; kwargs...)
+end
+
 """
 All user-facing indices are xor'd with this mask to produce unusual indices.
 This is good at catching bugs in solvers which assume indices are ordered 1, 2,

test/Utilities/mockoptimizer.jl

@@ -285,6 +285,28 @@ function test_is_set_by_optimize_optimizer_attribute()
     return
 end
 
+function test_empty_constructor()
+    mock = MOI.Utilities.MockOptimizer(Int; supports_names = false)
+    @test mock.supports_names == false
+    @test isa(
+        mock,
+        MOI.Utilities.MockOptimizer{
+            MOI.Utilities.UniversalFallback{MOI.Utilities.Model{Int}},
+            Int,
+        },
+    )
+    mock = MOI.Utilities.MockOptimizer()
+    @test mock.supports_names
+    @test isa(
+        mock,
+        MOI.Utilities.MockOptimizer{
+            MOI.Utilities.UniversalFallback{MOI.Utilities.Model{Float64}},
+            Float64,
+        },
+    )
+    return
+end
+
 end  # module
 
 TestMockOptimizer.runtests()