fix(base): fix resolving multiple ../ and add test (#52)

lua/pathlib/base.lua

@@ -121,6 +121,9 @@ function Path:_init(...)
         self:copy_all_from(s)
       else
         assert(not s:is_absolute(), ("new: invalid root path object in %sth argument: %s"):format(i, s))
+        if s:peek(1) == ".." then
+          run_resolve = true
+        end
         self._raw_paths:extend(s._raw_paths)
       end
     elseif type(s) == "string" then
@@ -525,11 +528,18 @@ end
 
 ---Resolves path. Eliminates `../` representation.
 ---Changes internal. (See `Path:resolve_copy` to create new object)
-function Path:resolve()
+---@param allow_abs2rel boolean|nil # Allow absolute path to be converted to relative path when there are too many '../'
+function Path:resolve(allow_abs2rel)
   local accum, length = 1, self:depth()
-  for _, value in ipairs(self._raw_paths) do
-    if value == ".." and accum > 1 then
-      accum = accum - 1
+  local negatives, was_absolute = 0, self:is_absolute()
+  local raw_path = table.concat(self._raw_paths, self.sep_str)
+  for _, value in ipairs(vim.tbl_values(self._raw_paths)) do
+    if value == ".." then
+      if accum > 1 then
+        accum = accum - 1
+      else
+        negatives = negatives + 1
+      end
     else
       self._raw_paths[accum] = value
       accum = accum + 1
@@ -538,27 +548,24 @@ function Path:resolve()
   for i = accum, length do
     self._raw_paths[i] = nil
   end
+  if not allow_abs2rel and was_absolute ~= self:is_absolute() then
+    errs.assert_function("Path:resolve", function()
+      return was_absolute == self:is_absolute()
+    end, string.format("'%s' was absolute but too many ../ included in path to resolve -> %s", raw_path, self))
+  end
+  for _ = 1, negatives do
+    table.insert(self._raw_paths, 1, "..")
+  end
   self.__string_cache = nil
   return self
 end
 
 ---Resolves path. Eliminates `../` representation and returns a new object. `self` is not changed.
+---@param allow_abs2rel boolean|nil # Allow absolute path to be converted to relative path when there are too many '../'
 ---@return PathlibPath
-function Path:resolve_copy()
-  local accum, length, new = 1, self:depth(), self:deep_copy()
-  for _, value in ipairs(self._raw_paths) do
-    if value == ".." and accum > 1 then
-      accum = accum - 1
-    else
-      new._raw_paths[accum] = value
-      accum = accum + 1
-    end
-  end
-  for i = accum, length do
-    new._raw_paths[i] = nil
-  end
-  new.__string_cache = nil
-  return new
+function Path:resolve_copy(allow_abs2rel)
+  local new = self:deep_copy()
+  return new:resolve(allow_abs2rel)
 end
 
 ---Run `vim.fn.globpath` on this path.

spec/resolve_spec.lua

@@ -0,0 +1,184 @@
+local _ = require("pathlib")
+
+describe("Resolve paths", function()
+  local Posix = require("pathlib.posix")
+  local Windows = require("pathlib.windows")
+  local utils = require("pathlib.utils")
+
+  local abs_posix = Posix("/etc")
+  local abs_win = Windows("C:/Users")
+  local rel_posix = Posix("./folder")
+  local rel_windows = Windows("./folder")
+
+  describe("Resolve relative Posix", function()
+    it("no ../", function()
+      assert.are_equal(Posix("folder/passwd"), rel_posix / "passwd")
+      assert.are_equal("folder/passwd", tostring(rel_posix / "passwd"))
+    end)
+    it("one ../", function()
+      assert.are_equal(Posix("var/lib"), rel_posix / "../var/lib")
+      assert.are_equal(Posix("var/lib"), rel_posix / ".." / "var/lib")
+      assert.are_equal(Posix("var/lib"), rel_posix.new(rel_posix .. "/../" .. "var/lib"))
+      assert.are_equal("var/lib", tostring(rel_posix / ".." / "var/lib"))
+    end)
+    it("too many ../", function()
+      assert.are_equal(Posix("../var/lib"), rel_posix / "../../var/lib")
+      assert.are_equal(Posix("../var/lib"), rel_posix / ".." / ".." / "var/lib")
+      assert.are_equal(Posix("../var/lib"), rel_posix.new(rel_posix .. "/../../" .. "var/lib"))
+      assert.are_equal("../var/lib", tostring(rel_posix / "../.." / "var/lib"))
+    end)
+    it("overflow ../", function()
+      assert.are_equal(Posix("../../var/lib"), rel_posix / "../../../var/lib")
+      assert.are_equal(Posix("../../var/lib"), rel_posix / ".." / ".." / ".." / "var/lib")
+      assert.are_equal(Posix("../../var/lib"), rel_posix.new(rel_posix .. "/../../../" .. "var/lib"))
+      assert.are_equal("../../var/lib", tostring(rel_posix / "../../.." / "var/lib"))
+    end)
+  end)
+
+  describe("Resolve multiple ../", function()
+    it("", function()
+      assert.are_equal(Posix("lib"), rel_posix / ".." / "var" / ".." / "lib")
+      assert.are_equal(Posix("lib"), rel_posix / "../var/../lib")
+    end)
+  end)
+
+  describe("Resolve relative Windows", function()
+    it("no ../", function()
+      assert.are_equal(Windows("folder/passwd"), rel_windows / "passwd")
+      assert.are_equal([[folder\passwd]], tostring(rel_windows / "passwd"))
+    end)
+    it("one ../", function()
+      assert.are_equal(Windows("var/lib"), rel_windows / "../var/lib")
+      assert.are_equal(Windows("var/lib"), rel_windows / ".." / "var/lib")
+      assert.are_equal(Windows("var/lib"), rel_windows.new(rel_windows .. "/../" .. "var/lib"))
+      assert.are_equal([[var\lib]], tostring(rel_windows / ".." / "var/lib"))
+    end)
+    it("too many ../", function()
+      assert.are_equal(Windows("../var/lib"), rel_windows / "../../var/lib")
+      assert.are_equal(Windows("../var/lib"), rel_windows / ".." / ".." / "var/lib")
+      assert.are_equal(Windows("../var/lib"), rel_windows.new(rel_windows .. "/../../" .. "var/lib"))
+      assert.are_equal([[..\var\lib]], tostring(rel_windows / "../.." / "var/lib"))
+    end)
+    it("overflow ../", function()
+      assert.are_equal(Windows("../../var/lib"), rel_windows / "../../../var/lib")
+      assert.are_equal(Windows("../../var/lib"), rel_windows / ".." / ".." / ".." / "var/lib")
+      assert.are_equal(Windows("../../var/lib"), rel_windows.new(rel_windows .. "/../../../" .. "var/lib"))
+      assert.are_equal([[..\..\var\lib]], tostring(rel_windows / [[../../..]] / [[var/lib]]))
+    end)
+  end)
+
+  describe("Resolve absolute Posix", function()
+    it("no ../", function()
+      assert.are_equal(Posix("/etc/passwd"), abs_posix / "passwd")
+      assert.are_equal("/etc/passwd", tostring(abs_posix / "passwd"))
+    end)
+    it("one ../", function()
+      assert.are_equal(Posix("/var/lib"), abs_posix / "../var/lib")
+      assert.are_equal(Posix("/var/lib"), abs_posix / ".." / "var/lib")
+      assert.are_equal(Posix("/var/lib"), abs_posix.new(abs_posix .. "/../" .. "var/lib"))
+      assert.are_equal("/var/lib", tostring(abs_posix / ".." / "var/lib"))
+    end)
+    it("too many ../", function()
+      assert.has_error(function()
+        return abs_posix / "../../var/lib"
+      end)
+      assert.has_error(function()
+        return abs_posix / ".." / ".." / "var/lib"
+      end)
+      assert.has_error(function()
+        return abs_posix.new(abs_posix .. "/../../" .. "var/lib")
+      end)
+      assert.has_error(function()
+        return tostring(abs_posix / "../.." / "var/lib")
+      end)
+    end)
+    it("overflow ../", function()
+      assert.has_error(function()
+        return abs_posix / "../../../var/lib"
+      end)
+      assert.has_error(function()
+        return abs_posix / ".." / ".." / ".." / "var/lib"
+      end)
+      assert.has_error(function()
+        return abs_posix.new(abs_posix .. "/../../../" .. "var/lib")
+      end)
+      assert.has_error(function()
+        return tostring(abs_posix / "../../.." / "var/lib")
+      end)
+
+      -- allow_abs2rel
+      assert.has_no_error(function()
+        return abs_posix:child_unpack("../../var/lib"):resolve(true)
+      end)
+      assert.are_equal(Posix("../var/lib"), abs_posix:descendant("..", "..", "..", "var", "lib"):resolve(true))
+    end)
+  end)
+
+  describe("Resolve absolute Windows", function()
+    it("no ../", function()
+      assert.are_equal(Windows("C:/Users/passwd"), abs_win / "passwd")
+      assert.are_equal([[C:\Users\passwd]], tostring(abs_win / "passwd"))
+    end)
+    it("one ../", function()
+      assert.are_equal(Windows([[C:\var\lib]]), abs_win / "../var/lib")
+      assert.are_equal(Windows([[C:\var\lib]]), abs_win / ".." / "var/lib")
+      assert.are_equal(Windows([[C:\var\lib]]), abs_win.new(abs_win .. "/../" .. "var/lib"))
+      assert.are_equal([[C:\var\lib]], tostring(abs_win / ".." / "var/lib"))
+    end)
+    it("too many ../", function()
+      assert.has_error(function()
+        return abs_win / "../../var/lib"
+      end)
+      assert.has_error(function()
+        return abs_win / ".." / ".." / "var/lib"
+      end)
+      assert.has_error(function()
+        return abs_win.new(abs_win .. "/../../" .. "var/lib")
+      end)
+      assert.has_error(function()
+        return tostring(abs_win / "../.." / "var/lib")
+      end)
+
+      -- allow_abs2rel
+      assert.has_no_error(function()
+        return abs_win:child_unpack([[..\..\var\lib]]):resolve(true)
+      end)
+      assert.are_equal(Windows([[C:../var/lib]]), abs_win:descendant("..", "..", "..", "var", "lib"):resolve(true))
+    end)
+    it("overflow ../", function()
+      assert.has_error(function()
+        return abs_win / "../../../var/lib"
+      end)
+      assert.has_error(function()
+        return abs_win / ".." / ".." / ".." / "var/lib"
+      end)
+      assert.has_error(function()
+        return abs_win.new(abs_win .. "/../../../" .. "var/lib")
+      end)
+      assert.has_error(function()
+        return tostring(abs_win / "../../.." / "var/lib")
+      end)
+    end)
+  end)
+
+  describe("Resolve multiple ../ in between", function()
+    it("posix", function()
+      assert.are_equal(Posix("lib"), rel_posix / ".." / "var" / ".." / "lib")
+      assert.are_equal(Posix("lib"), rel_posix / "../var/../lib")
+    end)
+
+    it("posix overflow", function()
+      assert.are_equal(Posix("../lib"), rel_posix / ".." / "var" / ".." / ".." / "lib")
+      assert.are_equal(Posix("../lib"), rel_posix / "../var/../../lib")
+    end)
+
+    it("windows", function()
+      assert.are_equal(Windows("lib"), rel_windows / ".." / "var" / ".." / "lib")
+      assert.are_equal(Windows("lib"), rel_windows / "../var/../lib")
+    end)
+    it("windows overflow", function()
+      assert.are_equal(Windows("../lib"), rel_windows / ".." / "var" / ".." / ".." / "lib")
+      assert.are_equal(Windows("../lib"), rel_windows / "../var/../../lib")
+    end)
+  end)
+end)