testConstraint testbytestring [llength [info commands testbytestring]]
testConstraint testchannel      [llength [info commands testchannel]]
testConstraint testfevent       [llength [info commands testfevent]]
testConstraint testchannelevent [llength [info commands testchannelevent]]
testConstraint testmainthread   [llength [info commands testmainthread]]
testConstraint testobj		[llength [info commands testobj]]
testConstraint testservicemode  [llength [info commands testservicemode]]
# Some things fail under Windows in Continuous Integration systems for subtle
# reasons such as CI often running with elevated privileges in a container.
testConstraint notWinCI [expr {
testConstraint knownMsvcBug [expr {![info exists ::env(TRAVIS_OS_NAME)] || ![string match windows $::env(TRAVIS_OS_NAME)]}]
    $::tcl_platform(platform) ne "windows" || ![info exists ::env(CI)]}]
testConstraint notOSX [expr {$::tcl_platform(os) ne "Darwin"}]

# You need a *very* special environment to do some tests.  In
# particular, many file systems do not support large-files...
testConstraint largefileSupport [expr {$::tcl_platform(os) ne "Darwin"}]

# some tests can only be run is umask is 2

    close $f
    lappend l [file size $path(test1)]
    set l
} {0 60 72}
set path(pipe)   [makeFile {} pipe]
set path(output) [makeFile {} output]
test io-27.6 {FlushChannel, async flushing, async close} \
	{stdio asyncPipeClose knownMsvcBug} {
	{stdio asyncPipeClose notWinCI} {
    # This test may fail on old Unix systems (seen on IRIX64 6.5) with
    # obsolete gettimeofday() calls.  See Tcl Bugs 3530533, 1942197.
    file delete $path(pipe)
    file delete $path(output)
    set f [open $path(pipe) w]
    puts $f "set f \[[list open $path(output) w]]"
    puts $f {

    # allow a little time for the background process to close.
    # otherwise, the following test fails on the [file delete $path(output)]
    # on Windows because a process still has the file open.
    after 100 set v 1; vwait v
    set result
} ok
test io-29.32 {Tcl_WriteChars, background flush to slow reader} \
	{stdio asyncPipeClose knownMsvcBug} {
	{stdio asyncPipeClose notWinCI} {
    # This test may fail on old Unix systems (seen on IRIX64 6.5) with
    # obsolete gettimeofday() calls.  See Tcl Bugs 3530533, 1942197.
    file delete $path(pipe)
    file delete $path(output)
    set f [open $path(pipe) w]
    puts $f "set f \[[list open $path(output) w]]"
    puts $f {fconfigure $f -translation lf}

    list [gets $c] [chan copy $c $outChan -size 100] [gets $c]
} -cleanup {
    close $outChan
    close $c
    removeFile out
} -result {line 100 line}

test io-54.1 {Recursive channel events} {socket fileevent knownMsvcBug} {
test io-54.1 {Recursive channel events} {socket fileevent notWinCI} {
    # This test checks to see if file events are delivered during recursive
    # event loops when there is buffered data on the channel.

    proc accept {s a p} {
	variable as
	fconfigure $s -translation lf
	puts $s "line 1\nline2\nline3"