Allo filepath.Join to take zero args as its underlying go implementation does and add tests for it

Author: scr-oath

filepath/api.go

@@ -94,11 +94,12 @@ func IsAbs(L *lua.LState) int {
 
 // Join lua fileapth.join(path, ...) joins any number of path elements into a single path, adding a Separator if necessary.
 func Join(L *lua.LState) int {
-	path := L.CheckString(1)
-	for i := 2; i <= L.GetTop(); i++ {
-		add := L.CheckAny(i).String()
-		path = filepath.Join(path, add)
+	var elems []string
+	for i := 1; i <= L.GetTop(); i++ {
+		elem := L.CheckAny(i).String()
+		elems = append(elems, elem)
 	}
+	path := filepath.Join(elems...)
 	L.Push(lua.LString(path))
 	return 1
 }

filepath/test/test_api.lua

@@ -10,6 +10,32 @@ function Test_join_and_separator(t)
     assert(path == need_path, string.format("expected %s; got %s", need_path, path))
 end
 
+function Test_join(t)
+    tests = {
+        {
+            name = "1/2/3",
+            args = { "1", "2", "3" },
+        },
+        {
+            name = "foo",
+            args = { "foo" },
+        },
+        {
+            name = "",
+            args = {},
+        },
+        {
+            name = "/a/b/c",
+            args = { "/", "a", "b", "c" },
+        },
+    }
+    for _, tt in ipairs(tests) do
+        t:Run(tt.name, function(t)
+            assert:Equal(t, tt.name, filepath.join(unpack(tt.args)))
+        end)
+    end
+end
+
 function Test_glob(t)
     local results = filepath.glob("test" .. filepath.separator() .. "*")
     assert(#results == 1, string.format("expected one glob result; got %d", #results))