put is upsert for files

spike/review/reinvent/ezmded/server/server_test.go

@@ -113,6 +113,29 @@ func TestServerPutTreeGetFile(t *testing.T) {
 	}
 	server.tree().Put("my pid", Branch{})
 	var id string
+	t.Run("put to create an id", func(t *testing.T) {
+		r := httptest.NewRequest(http.MethodPut, "/my-put-id", strings.NewReader("body"))
+		r.Header.Set("Title", "my put title")
+		r.Header.Set("PID", "my pid")
+		w := httptest.NewRecorder()
+		if err := server.apiV0FilesIDHandler(w, r); err != nil {
+			t.Fatal(err)
+		}
+		if w.Code != http.StatusOK {
+			t.Fatal(w)
+		}
+		var resp struct {
+			Data struct {
+				FilePath string `json:"filePath"`
+			} `json:"data"`
+		}
+		if err := json.NewDecoder(w.Body).Decode(&resp); err != nil {
+			t.Fatal(err)
+		}
+		if path.Base(resp.Data.FilePath) != "my-put-id" {
+			t.Fatal(resp.Data.FilePath)
+		}
+	})
 	t.Run("post", func(t *testing.T) {
 		r := httptest.NewRequest(http.MethodPost, "/", strings.NewReader("body"))
 		r.Header.Set("Title", "my title")