rails/rails — pull request #15293 by schneems (2014-05-24 12:11:28+00:00)
Title: print generators on failed generate

Let's say we just ran:

```
$ rails g migrate add_click_to_issue_assignment
```

We will get an error that looks like:

```
Could not find generator migrate.
```

This patch adds all existing migrations to the output to make it easier for a developer to find a valid migration.

```
Could not find generator "migrate". Please select a valid generator:
Rails:
assets
controller
generator
helper
integration_test
mailer
migration
model
resource
scaffold
scaffold_controller
task
```

It would be nice to do some spelling detection and suggest alternatives, but for now this should help.