Add Attach A File With Capybara as a rails til

rails/attach-a-file-with-capybara.md

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+# Attach A File With Capybara
+
+There are two ways to attach a file with
+[Capybara](https://github.com/jnicklas/capybara). The more conventional way
+is with the
+[`attach_file`](http://www.rubydoc.info/github/jnicklas/capybara/Capybara%2FNode%2FActions%3Aattach_file)
+method.
+
+Assuming there is a form with a file input similar to the following:
+
+```html
+<label for='data-file'>Data File</label>
+<input type='file' name='data-file' />
+```
+
+```ruby
+attach_file('data-file', 'path/to/file.csv')
+```
+
+The first argument to `attach_file` is a locator which refers to the `name`
+attribute on the `input` tag.
+
+If for some reason there is no `name` attribute on the `input` tag, the file
+can be attached with a standard `find` and `set`.
+
+```ruby
+find('form input[type="file"]').set('path/to/file.csv')
+```