diff --git a/CONTRIBUTE.md b/CONTRIBUTE.md
new file mode 100644
index 0000000..56df80e
--- /dev/null
+++ b/CONTRIBUTE.md
@@ -0,0 +1,18 @@
+# Contribute
+
+## Lint
+
+Use [lua-language-server](https://github.com/LuaLS/lua-language-server) for code
+lint.
+
+## Formatting
+
+Use [stylua](https://github.com/JohnnyMorganz/StyLua) for code formatting.
+
+## Test
+
+Start neovim and run:
+
+```lua
+require('gitlinker.test.test_rules')
+```
diff --git a/README.md b/README.md
index 0eb2d70..d2e840f 100644
--- a/README.md
+++ b/README.md
@@ -194,13 +194,3 @@ require('gitlinker').setup({
   file_log = false,
 })
 ````
-
-## Contribute
-
-### Code format
-
-Use [stylua](https://github.com/JohnnyMorganz/StyLua) for code formatting.
-
-### Test pattern rules
-
-Run test cases in [lua/gitlinker/test](https://github.com/linrongbin16/gitlinker.nvim/tree/master/lua/gitlinker/test).
diff --git a/lua/gitlinker.lua b/lua/gitlinker.lua
index 7b8e6ae..d621d49 100644
--- a/lua/gitlinker.lua
+++ b/lua/gitlinker.lua
@@ -311,6 +311,8 @@ end
 local M = {
   setup = setup,
   link = link,
+  -- for unit testing
+  map_remote_to_host = map_remote_to_host,
 }
 
 return M