diff --git a/test/defaults.jl b/test/defaults.jl
index 6a32073..6b77229 100644
--- a/test/defaults.jl
+++ b/test/defaults.jl
@@ -24,19 +24,31 @@
     @test isnothing(A.metabolite_formula(m, ""))
     @test isnothing(A.metabolite_charge(m, ""))
     @test isnothing(A.metabolite_compartment(m, ""))
+    @test isempty(A.couplings(m))
+    @test A.a_couplings(m) == 0
+    @test_throws ErrorException A.coupling(m)
+    @test all(isempty, A.coupling_bounds(m))
+    @test_throws ErrorException A.coupling_weights(m, "")
 
     @test isempty(A.reaction_annotations(m, ""))
     @test isempty(A.metabolite_annotations(m, ""))
     @test isempty(A.gene_annotations(m, ""))
+    @test isempty(A.coupling_annotations(m, ""))
     @test isempty(A.reaction_notes(m, ""))
     @test isempty(A.metabolite_notes(m, ""))
     @test isempty(A.gene_notes(m, ""))
+    @test isempty(A.coupling_notes(m, ""))
     @test isnothing(A.reaction_name(m, ""))
     @test isnothing(A.metabolite_name(m, ""))
     @test isnothing(A.gene_name(m, ""))
+    @test isnothing(A.coupling_name(m, ""))
 
     @test_throws ErrorException A.load(NotAModel, ".")
     @test_throws ErrorException A.save(m, ".")
     @test_throws ErrorException A.filename_extensions(NotAModel)
     @test_throws ErrorException show(stdout, MIME"text/plain"(), m)
+
+    A.n_reactions(::NotAModel) = 123
+
+    @test size(A.coupling(m) == (0, 123))
 end