yak(credo-strict-tuned-config-both-apps-x02d): credo strict, tuned config (both apps)

blogex/test/blogex/link_error_test.exs

@@ -0,0 +1,44 @@
+defmodule Blogex.LinkErrorTest do
+  @moduledoc """
+  Pins the rendered exception message, not just the struct.
+
+  The message is what a compile-time failure shows a human: the indentation and
+  the newline between errors are load-bearing. This is a characterization test
+  written before `message/1` was rewritten (`Enum.map/2 |> Enum.join/2` ->
+  `Enum.map_join/3`), so it passes on both sides of that change by design - it
+  exists to make the rewrite safe, not to prove new behaviour.
+  """
+  use ExUnit.Case, async: true
+
+  test "message/1 renders one indented line per error" do
+    error = %Blogex.LinkError{
+      blog: :engineering,
+      post_id: "my-post",
+      errors: [
+        {1, "/blog/unknown/broken", "unknown blog ID: unknown", [post_id: "my-post"]},
+        {7, "/blog/engineering/", "empty slug", [post_id: "my-post"]}
+      ]
+    }
+
+    assert Exception.message(error) == """
+           invalid internal blog links in engineering (post: my-post)
+
+             line 1: /blog/unknown/broken — unknown blog ID: unknown
+             line 7: /blog/engineering/ — empty slug
+           """
+  end
+
+  test "message/1 omits the post label when there is no post id" do
+    error = %Blogex.LinkError{
+      blog: :engineering,
+      post_id: nil,
+      errors: [{3, "/blog/unknown/broken", "unknown blog ID: unknown", []}]
+    }
+
+    assert Exception.message(error) == """
+           invalid internal blog links in engineering
+
+             line 3: /blog/unknown/broken — unknown blog ID: unknown
+           """
+  end
+end