add unit test for constructor duplicate

tests/Main.idr

@@ -47,6 +47,7 @@ idrisTests
        -- Error messages
        "error001", "error002", "error003", "error004", "error005",
        "error006", "error007", "error008", "error009", "error010",
+       "error011",
        -- Modules and imports
        "import001", "import002", "import003", "import004",
        -- Interactive editing support

tests/idris2/error011/ConstructorDuplicate.idr

@@ -0,0 +1,5 @@
+data A = B | B
+
+data C : Type -> Type where
+  D : C Int
+  D : C String

tests/idris2/error011/expected

@@ -0,0 +1,3 @@
+1/1: Building ConstructorDuplicate (ConstructorDuplicate.idr)
+ConstructorDuplicate.idr:1:14--3:1:Main.B is already defined
+ConstructorDuplicate.idr:5:3--5:15:Main.D is already defined

tests/idris2/error011/run

@@ -0,0 +1,3 @@
+$1 ConstructorDuplicate.idr --check
+
+rm -rf build