Improve Template#inspect output (#35407)

* Don't call inspect from identifier_method_name

* Add locals Template#inspect

Handler, formats, and variant are usually obvious from looking at the
identifier. However it's not uncommon to have different locals for the
same template so we should make that obvious in inspect.

* Add tests for short_identifier and inspect

[John Hawthorn + Rafael Mendonça França]

2 files changed, 16 insertions, 2 deletions

diff --git a/actionview/lib/action_view/template.rb b/actionview/lib/action_view/template.rb
index cc5e0cbb4f..ca387e9229 100644
--- a/actionview/lib/action_view/template.rb
+++ b/actionview/lib/action_view/template.rb
@@ -203,8 +203,12 @@ module ActionView
       end
     end
 
+    def short_identifier
+      @short_identifier ||= defined?(Rails.root) ? identifier.sub("#{Rails.root}/", "") : identifier
+    end
+
     def inspect
-      @inspect ||= defined?(Rails.root) ? identifier.sub("#{Rails.root}/", "") : identifier
+      "#<#{self.class.name} #{short_identifier} locals=#{@locals.inspect}>"
     end
 
     # This method is responsible for properly setting the encoding of the
@@ -378,7 +382,7 @@ module ActionView
       end
 
       def identifier_method_name
-        inspect.tr("^a-z_", "_")
+        short_identifier.tr("^a-z_", "_")
       end
 
       def instrument(action, &block) # :doc:
diff --git a/actionview/test/template/template_test.rb b/actionview/test/template/template_test.rb
index 36caef28c2..c74305fb42 100644
--- a/actionview/test/template/template_test.rb
+++ b/actionview/test/template/template_test.rb
@@ -215,4 +215,14 @@ class TestERBTemplate < ActiveSupport::TestCase
   ensure
     silence_warnings { Encoding.default_external = old }
   end
+
+  def test_short_identifier
+    @template = new_template("hello")
+    assert_equal "hello template", @template.short_identifier
+  end
+
+  def test_template_inspect
+    @template = new_template("hello")
+    assert_equal "#<ActionView::Template hello template locals=[]>", @template.inspect
+  end
 end