Add elixir 1.19.x compatibility (#107)

* Add elixir 1.19 to CI
* Fix type violation warning

Author: Geekfish

.github/workflows/main.yml

@@ -41,6 +41,8 @@ jobs:
             elixir: 1.17.x
           - otp: 27.x
             elixir: 1.18.x
+          - otp: 27.x
+            elixir: 1.19.x
     env:
       MIX_ENV: test
     steps:

lib/mimic/module.ex

@@ -129,13 +129,12 @@ defmodule Mimic.Module do
   if @elixir_version >= 1.18 do
     defp generate_mimic_struct(module) do
       if function_exported?(module, :__info__, 1) && module.__info__(:struct) != nil do
-        struct_info = module.__info__(:struct)
-
         struct_template = Map.from_struct(module.__struct__())
 
         struct_params =
-          for %{field: field} <- struct_info,
-              do: {field, Macro.escape(struct_template[field])}
+          Enum.map(module.__info__(:struct), fn %{field: field} ->
+            {field, Macro.escape(struct_template[field])}
+          end)
 
         quote do
           defstruct unquote(struct_params)

test/mimic_test.exs

@@ -1103,26 +1103,42 @@ defmodule Mimic.Test do
              }
     end
 
-    if @elixir_version >= 1.18 do
-      test "copies struct fields" do
-        StructNoEnforceKeys
-        |> stub(:bar, fn -> @stubbed end)
-
-        assert StructNoEnforceKeys.__info__(:struct) == [
-                 %{field: :foo, default: nil},
-                 %{field: :bar, default: nil}
-               ]
-      end
-    else
-      test "copies struct fields" do
-        StructNoEnforceKeys
-        |> stub(:bar, fn -> @stubbed end)
-
-        assert StructNoEnforceKeys.__info__(:struct) == [
-                 %{field: :foo, required: false},
-                 %{field: :bar, required: false}
-               ]
-      end
+    cond do
+      @elixir_version >= 1.19 ->
+        test "copies struct fields" do
+          StructNoEnforceKeys
+          |> stub(:bar, fn -> @stubbed end)
+
+          # Why pattern matching:
+          # Direct comparison causes the compiler to emit a warning.
+          # The `default` key may or may not exist in the struct info.
+          assert [
+                   %{field: :foo, default: nil, required: false},
+                   %{field: :bar, default: nil, required: false}
+                 ] = StructNoEnforceKeys.__info__(:struct)
+        end
+
+      @elixir_version >= 1.18 ->
+        test "copies struct fields" do
+          StructNoEnforceKeys
+          |> stub(:bar, fn -> @stubbed end)
+
+          assert StructNoEnforceKeys.__info__(:struct) == [
+                   %{field: :foo, default: nil},
+                   %{field: :bar, default: nil}
+                 ]
+        end
+
+      true ->
+        test "copies struct fields" do
+          StructNoEnforceKeys
+          |> stub(:bar, fn -> @stubbed end)
+
+          assert StructNoEnforceKeys.__info__(:struct) == [
+                   %{field: :foo, required: false},
+                   %{field: :bar, required: false}
+                 ]
+        end
     end
 
     test "protocol still works" do