source: downloads/tcl8.5.2/tests/winTime.test @ 44

# This file tests the tclWinTime.c file.
#
# This file contains a collection of tests for one or more of the Tcl
# built-in commands.  Sourcing this file into Tcl runs the tests and
# generates output for errors.  No output means no errors were found.
#
# Copyright (c) 1997 Sun Microsystems, Inc.
# Copyright (c) 1998-1999 by Scriptics Corporation.
#
# See the file "license.terms" for information on usage and redistribution
# of this file, and for a DISCLAIMER OF ALL WARRANTIES.
#
# RCS: @(#) $Id: winTime.test,v 1.10 2004/06/23 15:36:59 dkf Exp $

if {[lsearch [namespace children] ::tcltest] == -1} {
    package require tcltest
    namespace import -force ::tcltest::*
}

testConstraint testwinclock [llength [info commands testwinclock]]

# The next two tests will crash on Windows if the check for negative
# clock values is not done properly.

test winTime-1.1 {TclpGetDate} {win} {
    set ::env(TZ) JST-9
    set result [clock format -1 -format %Y]
    unset ::env(TZ)
    set result
} {1970}
test winTime-1.2 {TclpGetDate} {win} {
    set ::env(TZ) PST8
    set result [clock format 1 -format %Y]
    unset ::env(TZ)
    set result
} {1969}

# Next test tries to make sure that the Tcl clock stays in step
# with the Windows clock.  30 sec really isn't enough,
# but how much time does a tester have patience for?

test winTime-2.1 {Synchronization of Tcl and Windows clocks} {testwinclock} {
    # May fail due to OS/hardware discrepancies.  See:
    # http://support.microsoft.com/default.aspx?scid=kb;en-us;274323
    set failed {}
    set ok 1
    foreach start_sec [testwinclock] break
    while { 1 } {
        foreach { sys_sec sys_usec tcl_sec tcl_usec } [testwinclock] break
        set diff [expr { $tcl_sec - $sys_sec
                         + 1.0e-6 * ( $tcl_usec - $sys_usec ) }]
        if { abs($diff) > 0.06 } {
            set failed "Tcl clock differs from system clock by $diff sec"
            break
        } else {
            testwinsleep 1
        }
        if { $sys_sec - $start_sec >= 30 } break
    }
    set failed
} {}

# cleanup
::tcltest::cleanupTests
return