请求处理失败；嵌套异常是java.lang.NullPointerException junit嘲笑

Question

我正在尝试对该方法进行测试，它给了我org.springframework.web.util.NestedServletException：请求处理失败；嵌套的异常是java.lang.NullPointerException，我不知道为什么，请有人帮我，这是我试图实现的测试

public void updateProcedure() throws Exception {
        Procedure procedure = new Procedure();
        procedure.setId(1);
        procedure.setContent("oumaima");
        procedure.setDescription("test");
        Media medias = new Media();
        medias.setId(1);
        medias.setType("image/png");
        medias.setUrl("C:\\files\\actualite\\32769\\adobexd.png");
        List<Media> allMedias = new ArrayList<Media>();
        allMedias.add(medias);
        procedure.setMedias(allMedias);
        User user = new User();
        user.setId(1);
        user.setNom("oumaima");
        procedure.setUser(user);
        long id = 0L;
        long id1 = 1L;
        Mockito.when(procedureService.getProcedureById(Mockito.<Long>any())).thenReturn(new Procedure());
        Mockito.when(procedureService.addOrEditProcedure(Mockito.any(Procedure .class))).thenReturn(procedure);
        mockMvc.perform(put("/procedure/update/{id}",procedure.getId()).param("idDeleted",Long.toString(id))
                .param("idDeleted",Long.toString(id1))
                .param("content",procedure.getContent())
                .param("description",procedure.getDescription())
        )
                .andExpect(status().isOk());
    }

这是我的方法

@PutMapping("/procedure/update/{id}")
    public Map<String,Object> editActualite(@PathVariable Long id, @Valid @RequestParam ArrayList<Long> idDeleted,
                                            @Valid @RequestParam String content, @Valid @RequestParam String description){
        Procedure proc = this.procService.getProcedureById(id);
        if(content.length() !=0) {
            proc.setContent(content);
        }
        if(description.length() !=0){
            proc.setDescription(description);
        }
        if(idDeleted.size() != 0) {
            for (int i = 0; i < idDeleted.size(); i++) {
                    this.mediaService.deleteMedia(idDeleted.get(i));
            }
        }
        this.procService.addOrEditProcedure(proc);
        return getProcedureWeb(proc);
    }
    public Map<String, Object> getProcedureWeb(Procedure procedure) {
        List<Media> medias = procedure.getMedias();
        List<MediaToByte> mediaToBytes = new ArrayList<MediaToByte>(); //here where I get the error
        for (int i = 0; i < medias.size(); i++) {
            MediaToByte mediaToByte = new MediaToByte(medias.get(i));
            mediaToBytes.add(mediaToByte);
        }
        final Map<String, Object> act = new HashMap<String, Object>();
        act.put("id", procedure.getId());
        act.put("description", procedure.getDescription());
        act.put("content", procedure.getContent());
        act.put("medias", mediaToBytes);
        act.put("user", procedure.getUser());
        act.put("date", procedure.getDate());
        return act;
    }