diff-lcs 1.4.4 - Fix broken formatting

- Resolve #65: Two different issues were reported:

  - Line numbers changed between 1.3 and 1.4. This change is intentional, but
    in comparing the output against `diff` for the new examples provided
    it became clear that for unified and context diffs, the last hunk was
    reporting incorrect hunk lengths (that is, if it was `12,4 11,8`, it should
    have been `12,3 11,7`. This has been resolved by providing
    `Diff::LCS::Hunk#diff` an additional parameter, `last` which defaults to
    `false`.

  - Net new lines were added in the middle of a unified diff hunk, which was
    incorrect. That is, we were getting:

    ```diff
    @@ -10,6 +11,10 @@
    recipe[j::default]
    recipe[k::default]
    recipe[l::default]
    +recipe[o::new]
    +recipe[p::new]
    +recipe[q::new]
    +recipe[r::new]
    recipe[m::default]
    recipe[n::default]
    ```

    instead of:

    ```diff
    @@ -12,3 +11,7 @@
    recipe[l::default]
    recipe[m::default]
    recipe[n::default]
    +recipe[o::new]
    +recipe[p::new]
    +recipe[q::new]
    +recipe[r::new]
    ```

    This has been resolved. The error was that `Diff::LCS::Block#diff_size` was
    applying `.abs` to its output, which is incorrect. We need to know the
    direction of the size for placing changes, but when determining the maximum
    block size for use in `Diff::LCS::Hunk#diff` calculations, we need to know
    the `.abs` size.

  - New tests were added to prevent these changes from regressing in the
    future, both as issue tests and as additional `ldiff` tests. These tests
    highlighted more issues with diff-lcs output as compared to `diff`,
    specifically the handling and reporting of missing newlines at the end of
    files. All of the issues highlighted were resolved and the structure of
    `ldiff` tests was changed so that it is easier to add new comparison files
    at any time.

- Resolve #35: Indicate that when comparing against custom objects, `#eql?`
  must be implemented such that objects that _resolve_ to the same meaning are
  _treated_ as the same meaning. This is important because the basic LCS
  algorithm uses a hash for position matching.

- Resolve #43: Provide a more meaningful error from `Diff::LCS::Hunk.new` if
  the `piece` provided does not create useful `Diff::LCS::Block`. It's
  extremely unlikely, this error will be more useful than `NoMethodError` being
  thrown.

- Resolve #44: `ldiff` binary detection failed to work correctly. It had been
  `!old_text or !new_text`, but the precedence of `or` broke that. It is now
  `!old_text || !new_text`.

Also:

- Ran Rubocop again. Updated configuration definitions, fixed some code
  formatting.

Contributing.md

@@ -1,84 +1,118 @@
 ## Contributing
 
-I value any contribution to Diff::LCS you can provide: a bug report, a feature
-request, or code contributions. Code contributions to Diff::LCS are especially
-<del>welcome</del>encouraged. Because Diff::LCS is a complex codebase, there
-are a few guidelines:
-
-*   Code changes *will not* be accepted without tests. The test suite is
-    written with [RSpec][].
-*   Match my coding style.
-*   Use a thoughtfully-named topic branch that contains your change. Rebase
-    your commits into logical chunks as necessary.
-*   Use [quality commit messages][].
-*   Do not change the version number; when your patch is accepted and a release
-    is made, the version will be updated at that point.
-*   Submit a GitHub pull request with your changes.
-*   New or changed behaviours require appropriate documentation.
+I value any contribution to Diff::LCS you can provide: a bug report, a
+feature request, or code contributions. Code contributions to Diff::LCS are
+especially <del>welcome</del>encouraged. Because Diff::LCS is a complex
+codebase, there are a few guidelines:
+
+- Code changes _will not_ be accepted without tests. The test suite is
+  written with [RSpec][].
+- Match my coding style.
+- Use a thoughtfully-named topic branch that contains your change. Rebase
+  your commits into logical chunks as necessary.
+- Use [quality commit messages][].
+- Do not change the version number; when your patch is accepted and a release
+  is made, the version will be updated at that point.
+- Submit a GitHub pull request with your changes.
+- New or changed behaviours require appropriate documentation.
 
 ### Test Dependencies
 
-Diff::LCS uses Ryan Davis’s [Hoe][] to manage the release process, and it adds
-a number of rake tasks. You will mostly be interested in:
+Diff::LCS uses Ryan Davis’s [Hoe][] to manage the release process, and it
+adds a number of rake tasks. You will mostly be interested in:
 
-    $ rake
+```sh
+$ rake
+```
 
 which runs the tests the same way that:
 
-    $ rake spec
-    $ rake travis
+```sh
+$ rake spec
+```
 
 will do.
 
 To assist with the installation of the development dependencies, I have
 provided a Gemfile pointing to the (generated) `diff-lcs.gemspec` file. This
 will permit you to do:
 
-    $ bundle install
+```sh
+$ bundle install
+```
 
 to get the development dependencies. If you aleady have `hoe` installed, you
 can accomplish the same thing with:
 
-    $ rake newb
+```sh
+$ rake newb
+```
 
 This task will install any missing dependencies, run the tests/specs, and
 generate the RDoc.
 
 You can run tests with code coverage analysis by running:
 
-    $ rake spec:coverage
+```sh
+$ rake spec:coverage
+```
 
 ### Workflow
 
 Here's the most direct way to get your work merged into the project:
 
-*   Fork the project.
-*   Clone down your fork (`git clone git://github.com/<username>/diff-lcs.git`).
-*   Create a topic branch to contain your change (`git checkout -b
-    my_awesome_feature`).
-*   Hack away, add tests. Not necessarily in that order.
-*   Make sure everything still passes by running `rake`.
-*   If necessary, rebase your commits into logical chunks, without errors.
-*   Push the branch up (`git push origin my_awesome_feature`).
-*   Create a pull request against halostatue/diff-lcs and describe what your
-    change does and the why you think it should be merged.
+- Fork the project.
+- Clone down your fork (`git clone git://github.com/<username>/diff-lcs.git`).
+- Create a topic branch to contain your change (`git checkout -b my_awesome_feature`).
+- Hack away, add tests. Not necessarily in that order.
+- Make sure everything still passes by running `rake`.
+- If necessary, rebase your commits into logical chunks, without errors.
+- Push the branch up (`git push origin my_awesome_feature`).
+- Create a pull request against halostatue/diff-lcs and describe what your
+  change does and the why you think it should be merged.
 
 ### Contributors
 
-*   Austin Ziegler created Diff::LCS.
-
-Thanks to everyone else who has contributed to Diff::LCS:
-
-*   Kenichi Kamiya
-*   Michael Granger
-*   Vít Ondruch
-*   Jon Rowe
-*   Koichi Ito
-*   Josef Strzibny
-*   Josh Bronson
-*   Mark Friedgan
-*   Akinori MUSHA
-
-[Rspec]: http://rspec.info/documentation/
+- Austin Ziegler created Diff::LCS.
+
+Thanks to everyone else who has contributed code or bug reports to Diff::LCS:
+
+- @ginriki
+- @joshbronson
+- @kevinmook
+- @mckaz
+- Akinori Musha
+- Artem Ignatyev
+- Brandon Fish
+- Camille Drapier
+- Cédric Boutillier
+- Gregg Kellogg
+- Jagdeep Singh
+- Jason Gladish
+- Jon Rowe
+- Josef Strzibny
+- Josep (@apuratepp)
+- Josh Bronson
+- Jun Aruga
+- Kenichi Kamiya
+- Kensuke Nagae
+- Kevin Ansfield
+- Koichi Ito
+- Mark Friedgan
+- Michael Granger
+- Myron Marston
+- Nicolas Leger
+- Oleg Orlov
+- Paul Kunysch
+- Pete Higgins
+- Peter Wagenet
+- Philippe Lafoucrière
+- Ryan Lovelett
+- Scott Steele
+- Simon Courtois
+- Tomas Jura
+- Vít Ondruch
+
+[rspec]: http://rspec.info/documentation/
 [quality commit messages]: http://tbaggery.com/2008/04/19/a-note-about-git-commit-messages.html
-[Hoe]: https://github.com/seattlerb/hoe
+[hoe]: https://github.com/seattlerb/hoe

History.md

@@ -8,8 +8,35 @@
   a more useful exception. [#43][]
 - Added documentation that should address custom object issues as reported in
   [#35][].
+
 - Fixed more diff errors, in part reported in [#65][].
 
+  - The use of `Numeric#abs` is incorrect in `Diff::LCS::Block#diff_size`.
+    The diff size _must_ be accurate for correct change placement.
+  - When selecting @max_diff_size in Diff::LCS::Hunk, choose it based on
+    `block.diff_size.abs`.
+  - Made a number of changes that will, unfortunately, increase allocations
+    at the cost of being safe with frozen strings.
+  - Add some knowledge that when `Diff::LCS::Hunk#diff` is called, that we
+    are processing the _last_ hunk, so some changes will be made to how the
+    output is generated.
+
+    - `old`, `ed`, and `reverse_ed` formats have no differences.
+    - `unified` format will report `\ No newline at end of file` given the
+      correct conditions, at most once. Unified range reporting also
+      differs for the last hunk such that the `length` of the range is
+      reduced by one.
+    - `context` format will report `\No newline at end of file` given the
+      correct conditions, up to once per "file". Context range reporting also
+      differs for the last hunk such that the `end` part of the range is
+      reduced by one to a minimum of one.
+
+- Added a bunch more tests for the cases above, and fixed `hunk_spec.rb` so
+  that the phrase being compared isn't nonsense French.
+
+- Updated formatting.
+- Added a Rake task to assist with manual testing on Ruby 1.8.
+
 ## 1.4.3 / 2020-06-29
 
 - Fixed several issues with the 1.4 on Rubies older than 2.0. Some of this was