更新：它被标记为[What does "The following object is masked from 'package:xxx' mean?的副本。我引用的错误消息是“inst / tests / tests.Rraw”中的3729（lastID = 1380）中的1个错误。上一个链接没有解决这个问题。 （见后续评论部分）。
我想知道test.data.table()中的这个错误意味着什么：
R version 3.2.0 (2015-04-16) -- "Full of Ingredients"
Copyright (C) 2015 The R Foundation for Statistical Computing
Platform: x86_64-unknown-linux-gnu (64-bit)
......
> library(data.table)
data.table 1.9.4 For help type: ?data.table
*** NB: by=.EACHI is now explicit. See README to restore previous behaviour.
> test.data.table()
Running /mnt/sdb1/R-3.2.0/lib/R/library/data.table/tests/tests.Rraw
Loading required package: reshape2
Loading required package: reshape
Attaching package: ?reshape?
The following objects are masked from ?package:reshape2?:
colsplit, melt, recast
Loading required package: plyr
Attaching package: ?plyr?
The following objects are masked from ?package:reshape?:
rename, round_any
Loading required package: ggplot2
Loading required package: hexbin
Loading required package: nlme
Loading required package: xts
Loading required package: bit64
Loading required package: gdata
gdata: read.xls support for 'XLS' (Excel 97-2004) files ENABLED.
gdata: read.xls support for 'XLSX' (Excel 2007+) files ENABLED.
Attaching package: ?gdata?
The following object is masked from ?package:data.table?:
last
The following object is masked from ?package:stats?:
nobs
The following object is masked from ?package:utils?:
object.size
Loading required package: GenomicRanges
Test 167.2 not run. If required call library(hexbin) first.
Don't know how to automatically pick scale for object of type ITime. Defaulting to continuous
Don't know how to automatically pick scale for object of type ITime. Defaulting to continuous
Test 841 not run. If required call library(xts) first.
Test 842 ran without errors but failed check that x equals y:
> x = last(list("a", 1:2, 89))
[[1]]
[1] 89
> y = 89
[1] 89
Tests 897-899 not run. If required call library(bit64) first.
Running test id 1362.1
Running test id 1362.2
Running test id 1362.3
Running test id 1362.4
Running test id 1362.5
Running test id 1362.6
Running test id 1362.7
Running test id 1362.8
Running test id 1362.9
Running test id 1362.11
Running test id 1362.12
Error in eval(expr, envir, enclos) :
1 error out of 3729 (lastID=1380) in inst/tests/tests.Rraw on Tue Jun 16 15:28:44 2015. Search tests.Rraw for test number 842.