Tests and docs for #752

README.md

@@ -513,6 +513,14 @@ end
 ```
 
 Renders the template string.
+You can optionally specify `:path` and `:line` for a clearer backtrace if there is
+a filesystem path or line associated with that string:
+
+```ruby
+get '/' do
+  haml '%div.title Hello World', :path => 'examples/file.haml', :line => 3
+end
+```
 
 ### Available Template Languages
 

lib/sinatra/base.rb

@@ -845,7 +845,9 @@ def compile_template(engine, data, options, views)
           end
         when Proc, String
           body = data.is_a?(String) ? Proc.new { data } : data
-          path, line = settings.caller_locations.first
+          caller = settings.caller_locations.first
+          path = options[:path] || caller[0]
+          line = options[:line] || caller[1]
           template.new(path, line.to_i, options, &body)
         else
           raise ArgumentError, "Sorry, don't know how to render #{data.inspect}."

test/templates_test.rb

@@ -100,6 +100,28 @@ def with_default_layout
     assert_equal 'Hello World', body
   end
 
+  it 'allows to specify path/line when rendering with String' do
+    path = 'example.txt'
+    line = 228
+    begin render_app {
+      render :erb, '<%= doesnotexist %>', {:path => path, :line => line}
+    }
+    rescue NameError => e
+      assert_match(/#{path}:#{line}/, e.backtrace.first)
+    end
+  end
+
+  it 'allows to specify path/line when rendering with Proc' do
+    path = 'example.txt'
+    line = 900
+    begin render_app {
+      render :erb, Proc.new { '<%= doesnotexist %>' }, {:path => path, :line => line}
+    }
+    rescue NameError => e
+      assert_match(/#{path}:#{line}/, e.backtrace.first)
+    end
+  end
+
   it 'renders Proc templates using the call result' do
     render_app { render(:test, Proc.new {'Hello World'}) }
     assert ok?