From 92bd470f0da0c4d97888bd257e7066f5d05a942a Mon Sep 17 00:00:00 2001
From: Violet Shreve <shreve@umich.edu>
Date: Mon, 3 Jul 2023 17:56:31 -0400
Subject: [PATCH] fix(path): make find_upwards() search root

The previous implementation of `Path:find_upwards()` used the loop
condition `folder ~= root` to bound the search which meant the root
directory would never be searched. This commit instead breaks the `while
true` loop after searching the root directory.

The function now also returns `nil` rather than a blank string to
indicate that the search has failed.

Finally, this commit adds specs for the function.
---
 lua/plenary/path.lua        |  5 ++++-
 tests/plenary/path_spec.lua | 28 ++++++++++++++++++++++++++++
 2 files changed, 32 insertions(+), 1 deletion(-)

diff --git a/lua/plenary/path.lua b/lua/plenary/path.lua
index 701679e6..0865f2e3 100644
--- a/lua/plenary/path.lua
+++ b/lua/plenary/path.lua
@@ -931,11 +931,14 @@ function Path:find_upwards(filename)
   local folder = Path:new(self)
   local root = path.root(folder:absolute())
 
-  while folder:absolute() ~= root do
+  while true do
     local p = folder:joinpath(filename)
     if p:exists() then
       return p
     end
+    if folder:absolute() == root then
+      break
+    end
     folder = folder:parent()
   end
   return nil
diff --git a/tests/plenary/path_spec.lua b/tests/plenary/path_spec.lua
index 8f916a30..0f02db04 100644
--- a/tests/plenary/path_spec.lua
+++ b/tests/plenary/path_spec.lua
@@ -721,6 +721,34 @@ SOFTWARE.]]
       assert.are.same(should, data)
     end)
   end)
+
+  describe(":find_upwards", function()
+    it("finds files that exist", function()
+      local p = Path:new(debug.getinfo(1, "S").source:sub(2))
+      local found = p:find_upwards "README.md"
+      assert.are.same(found:absolute(), Path:new("README.md"):absolute())
+    end)
+
+    it("finds files that exist at the root", function()
+      local p = Path:new(debug.getinfo(1, "S").source:sub(2))
+
+      -- Temporarily set path.root to the root of this repository
+      local root = p.path.root
+      p.path.root = function(_)
+        return p:parent():parent():parent().filename
+      end
+
+      local found = p:find_upwards "README.md"
+      assert.are.same(found:absolute(), Path:new("README.md"):absolute())
+      p.path.root = root
+    end)
+
+    it("returns nil if no file is found", function()
+      local p = Path:new(debug.getinfo(1, "S").source:sub(2))
+      local found = p:find_upwards "MISSINGNO.md"
+      assert.are.same(found, nil)
+    end)
+  end)
 end)
 
 -- function TestPath:testIsDir()