diff-lcs 1.4.4 - Fix broken formattingmisplaced-chunk-issue-65

- 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.

1 files changed, 27 insertions, 0 deletions

diff --git a/History.md b/History.md
index 3690990..063387b 100644
--- a/History.md
+++ b/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