neiam /gitgud

defmodule GitGud.Git.DiffParserTest do
  use ExUnit.Case, async: true

  alias GitGud.Git.DiffParser

  test "parses a simple modify with one hunk" do
    text = """
    diff --git a/lib/foo.ex b/lib/foo.ex
    index 1111111..2222222 100644
    --- a/lib/foo.ex
    +++ b/lib/foo.ex
    @@ -1,3 +1,4 @@
     defmodule Foo do
    -  def x, do: 1
    +  def x, do: 2
    +  def y, do: 3
     end
    """

    assert [file] = DiffParser.parse(text)
    assert file.path == "lib/foo.ex"
    assert file.status == :modified
    assert file.insertions == 2
    assert file.deletions == 1
    assert [hunk] = file.hunks
    assert hunk.old_start == 1 and hunk.old_count == 3
    assert hunk.new_start == 1 and hunk.new_count == 4

    types = Enum.map(hunk.lines, & &1.type)
    assert types == [:context, :del, :add, :add, :context]
  end

  test "tracks line numbers correctly across context + add + del" do
    text = """
    diff --git a/a.txt b/a.txt
    --- a/a.txt
    +++ b/a.txt
    @@ -10,3 +10,4 @@
     ten
    -eleven
    +eleven new
    +bonus
     twelve
    """

    [%{hunks: [hunk]}] = DiffParser.parse(text)

    assert Enum.map(hunk.lines, fn l -> {l.type, l.old_line, l.new_line} end) == [
             {:context, 10, 10},
             {:del, 11, nil},
             {:add, nil, 11},
             {:add, nil, 12},
             {:context, 12, 13}
           ]
  end

  test "added file (old side /dev/null)" do
    text = """
    diff --git a/new.txt b/new.txt
    new file mode 100644
    --- /dev/null
    +++ b/new.txt
    @@ -0,0 +1,2 @@
    +line one
    +line two
    """

    assert [file] = DiffParser.parse(text)
    assert file.status == :added
    assert file.path == "new.txt"
    assert file.insertions == 2
    assert file.deletions == 0
  end

  test "deleted file (new side /dev/null)" do
    text = """
    diff --git a/old.txt b/old.txt
    deleted file mode 100644
    --- a/old.txt
    +++ /dev/null
    @@ -1,2 +0,0 @@
    -gone
    -bye
    """

    assert [file] = DiffParser.parse(text)
    assert file.status == :deleted
    assert file.path == "old.txt"
    assert file.deletions == 2
  end

  test "binary file produces an empty-hunk record flagged binary" do
    text = """
    diff --git a/img.png b/img.png
    index abc..def 100644
    Binary files a/img.png and b/img.png differ
    """

    assert [file] = DiffParser.parse(text)
    assert file.binary?
    assert file.hunks == []
  end

  test "handles `\\ No newline at end of file` marker gracefully" do
    text = """
    diff --git a/a.txt b/a.txt
    --- a/a.txt
    +++ b/a.txt
    @@ -1 +1 @@
    -old
    \\ No newline at end of file
    +new
    """

    [%{hunks: [hunk]}] = DiffParser.parse(text)
    assert Enum.map(hunk.lines, & &1.type) == [:del, :add]
  end

  test "multiple files in one diff" do
    text = """
    diff --git a/a.txt b/a.txt
    --- a/a.txt
    +++ b/a.txt
    @@ -1 +1 @@
    -a
    +A
    diff --git a/b.txt b/b.txt
    --- a/b.txt
    +++ b/b.txt
    @@ -1 +1 @@
    -b
    +B
    """

    files = DiffParser.parse(text)
    assert length(files) == 2
    assert Enum.map(files, & &1.path) == ["a.txt", "b.txt"]
  end

  test "empty input returns []" do
    assert DiffParser.parse("") == []
  end
end