Improve error message for models with wrong number of interfaces

Author: wouterwln

src/model_macro.jl

@@ -737,6 +737,17 @@ function get_make_node_function(ms_body, ms_args, ms_name)
             $ms_body
         end
 
+        function GraphPPL.add_terminated_submodel!(
+            __model__::GraphPPL.Model,
+            __context__::GraphPPL.Context,
+            __options__::GraphPPL.NodeCreationOptions,
+            __fform__::typeof($ms_name),
+            __interfaces__::NamedTuple,
+            any::GraphPPL.StaticInt{N}
+        ) where {N}
+            error("Model $(__fform__) is not defined for $(N) interfaces ($(keys(__interfaces__))).")
+        end
+
         function ($ms_name)(; kwargs...)
             return GraphPPL.ModelGenerator($ms_name, kwargs)
         end

src/plugins/variational_constraints/variational_constraints.jl

@@ -97,4 +97,4 @@ function postprocess_plugin(plugin::VariationalConstraintsPlugin, model::Model)
     end
     apply_constraints!(model, GraphPPL.get_principal_submodel(model), plugin.constraints)
     materialize_constraints!(model)
-end
+end

test/model_generator_tests.jl

@@ -158,7 +158,9 @@ end
             return (a = 2, observation = 3)
         end
         # Too many keys, `c = 1` is extra
-        @test_throws MethodError create_model(generator) do model, ctx
+        @test_throws "Model simple_model_for_model_generator is not defined for 4 interfaces ((:c, :a, :b, :observation))." create_model(
+            generator
+        ) do model, ctx
             return (a = 1, b = 2, observation = 3)
         end
     end

test/model_macro_tests.jl

@@ -2016,3 +2016,22 @@ end
 
     @test default_backend(hello) === TestUtils.TestGraphPPLBackend()
 end
+
+@testitem "error message for other number of interfaces" begin
+    using GraphPPL
+    using Distributions
+
+    import GraphPPL: @model
+
+    @model function somemodel(a, b, c)
+        a ~ Normal(b, c)
+    end
+
+    @test_throws "Model somemodel is not defined for 2 interfaces" GraphPPL.create_model(somemodel(a = 1, b = 2))
+
+    @model function somemodel(a, b)
+        c ~ Normal(b, a)
+    end
+
+    @test !isnothing(GraphPPL.create_model(somemodel(a = 1, b = 2)))
+end