fix: allow converting a file to directory and vice-versa (#117)

If you rename a file to have a `/` at the end, oil will detect the
change as a delete + new directory. Similarly, if you delete the
trailing `/` from a directory, it will delete the dir and create a new
file. This should help with the case where you want to create a new file
but forgot to add the trailing `/` and now you have a file instead.

lua/oil/mutator/parser.lua

@@ -207,6 +207,12 @@ M.parse = function(bufnr)
             entry_type = "link",
             link = parsed_entry.link_target,
           })
+        elseif entry[FIELD_TYPE] ~= parsed_entry._type then
+          table.insert(diffs, {
+            type = "new",
+            name = parsed_entry.name,
+            entry_type = parsed_entry._type,
+          })
         else
           original_entries[parsed_entry.name] = nil
         end

tests/mutator_spec.lua

@@ -200,6 +200,20 @@ a.describe("mutator", function()
       }, diffs)
     end)
 
+    it("detects a new trailing slash as a delete + create", function()
+      local file = test_adapter.test_set("/foo", "file")
+      vim.cmd.edit({ args = { "oil-test:///" } })
+      local bufnr = vim.api.nvim_get_current_buf()
+      set_lines(bufnr, {
+        string.format("/%d foo/", file[FIELD_ID]),
+      })
+      local diffs = parser.parse(bufnr)
+      assert.are.same({
+        { type = "new", name = "foo", entry_type = "directory" },
+        { type = "delete", id = file[FIELD_ID], name = "foo" },
+      }, diffs)
+    end)
+
     it("detects renamed files that conflict", function()
       local afile = test_adapter.test_set("/foo/a.txt", "file")
       local bfile = test_adapter.test_set("/foo/b.txt", "file")