Add additional expression-default tests

Author: MilesCranmer

test/model_def.jl

@@ -157,20 +157,28 @@ end
     @mlj_model mutable struct Foo1
         a::Vector{Int} = [1, 2, 3]
     end
-    Foo1().a == [1, 2, 3]
+    @test Foo1().a == [1, 2, 3]
     @mlj_model mutable struct Foo2
         a::Vector{Int} = [1, 2, 3]::(true)
     end
-    Foo2().a == [1, 2, 3]
+    @test Foo2().a == [1, 2, 3]
 
-    # Negative number:
+    # Constraints applied
     @mlj_model mutable struct Foo3
-        a::Float64 = -1.0
+        a::Vector{Int} = [1, 2, 3]::(all(>(0), _))
     end
-    Foo3().a === -1.0
+    @test redirect_stderr(devnull) do
+        Foo3(; a = [-1]).a == [1, 2, 3]
+    end
+
+    # Negative number:
     @mlj_model mutable struct Foo4
+        a::Float64 = -1.0
+    end
+    @test Foo4().a === -1.0
+    @mlj_model mutable struct Foo5
         a::Float64 = (-1.0)::(true)
     end
-    Foo4().a == -1.0
+    @test Foo5().a == -1.0
 
 end