Restructure credentials after environment overrides.

Follow up to: e0d3313

- Revert renames from `encrypted` and `encrypted_file` back to `credentials`.
  They might be using our Encrypted* generators but from that level of abstraction
  they're still about credentials.

- Same vein: extract a `credentials` method for the `encrypted` local variable. But
  don't call it `encrypted` just because it uses that under the hood. It's about
  capturing the credentials. It's also useful in `change_credentials_in_system_editor`.

- Remove lots of needless argument passing. We've abstracted content_path and key_path
  into methods for a reason, so they should be used. Also spares a conspicuous rename
  of content_path into file_path in other methods.

- Reorders private methods so they're grouped into: command building blocks, option
  parsers, and the generators.

- Extracts commonality in the credentials application tests. A tad unsure about this.
  But I do like that we go with key, content thus matching the command and remove the
  yield which isn't really needed.

- Moves test/credentials_test.rb to beneath the test/application directory. It's a
  Rails application test, so it should be in there.

- Uses `root.join` — a neat trick gleaned from the tests! — and composes the configuration
  private methods such that the building block is below the callers.

1 files changed, 13 insertions, 5 deletions

diff --git a/railties/CHANGELOG.md b/railties/CHANGELOG.md
index 673b6eac86..aca55fae80 100644
--- a/railties/CHANGELOG.md
+++ b/railties/CHANGELOG.md
@@ -116,12 +116,20 @@
 
     *Richard Schneeman*
 
-*   Support environment specific credentials file.
+*   Support environment specific credentials overrides.
 
-    For `production` environment look first for `config/credentials/production.yml.enc` file that can be decrypted by
-    `ENV["RAILS_MASTER_KEY"]` or `config/credentials/production.key` master key.
-    Edit given environment credentials file by command `rails credentials:edit --environment production`.
-    Default paths can be overwritten by setting `config.credentials.content_path` and `config.credentials.key_path`.
+    So any environment will look for `config/credentials/#{Rails.env}.yml.enc` and fall back
+    to `config/credentials.yml.enc`.
+
+    The encryption key can be in `ENV["RAILS_MASTER_KEY"]` or `config/credentials/production.key`.
+
+    Environment credentials overrides can be edited with `rails credentials:edit --environment production`.
+    If no override is setup for the passed environment, it will be created.
+
+    Additionally, the default lookup paths can be overwritten with these configs:
+
+    - `config.credentials.content_path`
+    - `config.credentials.key_path`
 
     *Wojciech Wnętrzak*