yak(pin-user-inspect-output-exactly-both-redacted-fields-shape-l0mg): pin User inspect output exactly (both redacted fields + shape)

app/test/firehose/accounts_test.exs

@@ -390,8 +390,57 @@ defmodule Firehose.AccountsTest do
   end
 
   describe "inspect/2 for the User module" do
-    test "does not include password" do
-      refute inspect(%User{password: "123456"}) =~ "password: \"123456\""
+    # Rendering is `#Firehose.Accounts.User<__meta__: ..., id: 42, ...>`: a
+    # single line that ends with `, ...>`. The tests below pin the stable parts
+    # (module name, one line, redaction, field names and values) rather than
+    # the full string, so a toolchain bump that changes formatting does not
+    # fail them.
+    test "redacts every field the schema marks redacted, by name and by value" do
+      user = %User{
+        id: 42,
+        email: "shape-pin@example.com",
+        password: "plaintext-secret-value",
+        hashed_password: "hashed-secret-value"
+      }
+
+      output = inspect(user)
+      redacted = User.__schema__(:redact_fields)
+
+      # Guard against a vacuous loop if the schema key ever changes meaning.
+      # (`match?` rather than a comparison against `[]`: the type checker
+      # proves this schema's literal list non-empty and warns on the compare.)
+      assert match?([_ | _], redacted)
+      # The two secrets this schema declares; ties the loop to real fields.
+      assert :password in redacted
+      assert :hashed_password in redacted
+
+      for field <- redacted do
+        refute output =~ Atom.to_string(field)
+        refute output =~ Map.fetch!(user, field)
+      end
+    end
+
+    test "renders a single struct line with non-redacted fields and values" do
+      user = %User{
+        id: 42,
+        email: "shape-pin@example.com",
+        password: "plaintext-secret-value",
+        hashed_password: "hashed-secret-value"
+      }
+
+      output = inspect(user)
+      redacted = User.__schema__(:redact_fields)
+
+      assert String.starts_with?(output, "#Firehose.Accounts.User<")
+      assert String.ends_with?(output, ">")
+      refute output =~ "\n"
+
+      assert output =~ "id: 42"
+      assert output =~ ~s(email: "shape-pin@example.com")
+
+      for %{field: field} <- User.__info__(:struct), field not in redacted do
+        assert output =~ Atom.to_string(field)
+      end
     end
   end
 end