tests: separate the tests for patch helper from other tools (olimorris#1666)

* Separate the tests for patch helper from other tools

This converts the tests for PATCH to individual unit tests. This makes
them much more faster to run. Plus it is makes them easier to edit.

* Added missing comment

Author: pratyushmittal

tests/strategies/chat/agents/tools/helpers/test_patch.lua

@@ -0,0 +1,117 @@
+local h = require("tests.helpers")
+local patch = require("codecompanion.strategies.chat.agents.tools.helpers.patch")
+
+local new_set = MiniTest.new_set
+
+local function readfile(path)
+  local lines = vim.fn.readfile(path)
+  return table.concat(lines, "\n")
+end
+
+local function apply_patch(input_str, patch_str)
+  -- 1. parse changes
+  local changes, had_begin_end_markers = patch.parse_changes(patch_str)
+
+  -- 2. read file into lines
+  local lines = vim.split(input_str, "\n", { plain = true })
+
+  -- 3. apply changes
+  for _, change in ipairs(changes) do
+    local new_lines = patch.apply_change(lines, change)
+    if new_lines == nil then
+      if had_begin_end_markers then
+        error(string.format("Bad/Incorrect diff:\n\n%s\n\nNo changes were applied", patch.get_change_string(change)))
+      else
+        error("Invalid patch format: missing Begin/End markers")
+      end
+    else
+      lines = new_lines
+    end
+  end
+  return table.concat(lines, "\n")
+end
+
+T = new_set()
+
+T["patch"] = new_set()
+T["patch"]["simple patch"] = function()
+  local input_str = "line1\nline2\nline3"
+  local patch_str = "*** Begin Patch\nline1\n-line2\n+new_line2\nline3\n*** End Patch"
+  local output_str = apply_patch(input_str, patch_str)
+  local expected_output = "line1\nnew_line2\nline3"
+  h.eq(output_str, expected_output)
+end
+
+T["patch"]["simple test from fixtures"] = function()
+  local input_str = readfile("tests/fixtures/files-input-1.html")
+  local patch_str = readfile("tests/fixtures/files-diff-1.1.patch")
+  local output_str = apply_patch(input_str, patch_str)
+  local expected_output = readfile("tests/fixtures/files-output-1.1.html")
+  h.eq(output_str, expected_output)
+end
+
+T["patch"]["empty lines"] = function()
+  local input_str = readfile("tests/fixtures/files-input-1.html")
+  local patch_str = readfile("tests/fixtures/files-diff-1.3.patch")
+  local output_str = apply_patch(input_str, patch_str)
+  local expected_output = readfile("tests/fixtures/files-output-1.3.html")
+  h.eq(output_str, expected_output)
+end
+
+T["patch"]["multiple patches"] = function()
+  local input_str = readfile("tests/fixtures/files-input-1.html")
+  local patch_str = readfile("tests/fixtures/files-diff-1.4.patch")
+  local output_str = apply_patch(input_str, patch_str)
+  local expected_output = readfile("tests/fixtures/files-output-1.4.html")
+  h.eq(output_str, expected_output)
+end
+
+T["patch"]["no BEGIN and END markers"] = function()
+  local input_str = readfile("tests/fixtures/files-input-1.html")
+  local patch_str = readfile("tests/fixtures/files-diff-1.5.patch")
+  local output_str = apply_patch(input_str, patch_str)
+  local expected_output = readfile("tests/fixtures/files-output-1.5.html")
+  h.eq(output_str, expected_output)
+end
+
+T["patch"]["multiple continuation"] = function()
+  local input_str = readfile("tests/fixtures/files-input-2.html")
+  local patch_str = readfile("tests/fixtures/files-diff-2.1.patch")
+  local output_str = apply_patch(input_str, patch_str)
+  local expected_output = readfile("tests/fixtures/files-output-2.1.html")
+  h.eq(output_str, expected_output)
+end
+
+T["patch"]["spaces"] = function()
+  local input_str = readfile("tests/fixtures/files-input-2.html")
+  local patch_str = readfile("tests/fixtures/files-diff-2.2.patch")
+  local output_str = apply_patch(input_str, patch_str)
+  local expected_output = readfile("tests/fixtures/files-output-2.2.html")
+  h.eq(output_str, expected_output)
+end
+
+T["patch"]["html spaces flexible"] = function()
+  local input_str = readfile("tests/fixtures/files-input-3.html")
+  local patch_str = readfile("tests/fixtures/files-diff-3.patch")
+  local output_str = apply_patch(input_str, patch_str)
+  local expected_output = readfile("tests/fixtures/files-output-3.html")
+  h.eq(output_str, expected_output)
+end
+
+T["patch"]["html line breaks"] = function()
+  local input_str = readfile("tests/fixtures/files-input-4.html")
+  local patch_str = readfile("tests/fixtures/files-diff-4.patch")
+  local output_str = apply_patch(input_str, patch_str)
+  local expected_output = readfile("tests/fixtures/files-output-4.html")
+  h.eq(output_str, expected_output)
+end
+
+T["patch"]["lua dashes"] = function()
+  local input_str = readfile("tests/fixtures/files-input-5.lua")
+  local patch_str = readfile("tests/fixtures/files-diff-5.patch")
+  local output_str = apply_patch(input_str, patch_str)
+  local expected_output = readfile("tests/fixtures/files-output-5.lua")
+  h.eq(output_str, expected_output)
+end
+
+return T