Some example packets for cut-n-paste testing:

position without timestamp:
JH6YLM>APRS,RELAY,TRACE5-5,qAo,JA6JMJ-3:!3210.70N/13132.15E#15 KAWA
PY3KN-1>WIDE1-1,TCPIP*,qAC,T2BRAZIL:=3003.96SI05106.10W&iGate Viamao
PD0TK-9>APERXQ,PA3GKF-2*,WIDE2-1,qAo,DB0SDA:!5057.18N/00549.40E>037/004/A=000353

position with timestamp:
N0YNC>APRS,TCPXX*,qAX,T2PSR:@271607z4028.82N/09657.64W_272/003g004t036r000P000p000h62b10206v31

object position with timestamp:
DB0XIP>APU25N,TCPIP*,qAC,THIRD:;DF0OV *181515z4915.09N/00725.45E-K35 www.k35-schwarzbachtal.de

compressed position:
OH7LZB-9>APZMDR,WIDE3-3,qAo,OH2RCH:!/0"acTjK">?S_ http://aprs.fi/

mic-e:
KG4PKR-1>SUSV9P,W4GGM-1,KA4BNI-2*,WIDE2,qAR,KB4YTM-1:'sZ&l!^K\]"6)}

---- q-construct tests ---

no Q construct
SRC>DST,DIGI1,DIGI2*:test

missing callsign after q construct?
user SRC
SRC>DST,DIGI1,DIGI2*,qAR,:test
SRC>DST,DIGI1,DIGI2*,qAR:test
SRC>DST,DIGI1,DIGI2*,qAR,A:test
SRC>DST,qAR,ASDF:test
SRC>DST,DIGI1,DIGI2*,qAR,IGATE:test

too many callsigns?
SRC>DST,DIGI1,DIGI2*,qAR,CALL1,CALL2:test

packet ends with qAR,LOGIN
user SRC pass 25520
FOO>BAR,DIGI1,qAR,SRC:test
SRC>BAR,DIGI1:test

packet ends with LOGIN,I or VIACALL,I
user SRC pass 25520
FOO>BAR,DIGI1,SRC,I:test
FOO>BAR,DIGI1,VIACALL,I:test

FOO>BAR,DIGI1:test

has a qAZ:
FOO>BAR,DIGI1,qAZ,ASDF1:foo

duplicate callsign after Q construct:
FOO>BAR,DIGI1,qAR,ASDF1,ASDF2,ASDF3:foo
FOO>BAR,DIGI1,qAR,ASDF1,ASDF1,ASDF1:foo
FOO>BAR,DIGI1,qAR,ASDF1,ASDF2,ASDF1:foo
FOO>BAR,DIGI1,qAR,ASDF,ASDF1,ASDF1:foo

my callsign after Q construct:
FOO>BAR,DIGI1,qAR,OH7LZB-13:foo
FOO>BAR,DIGI1,qAR,OH7LZB-13,ASDF:foo
FOO>BAR,DIGI1,qAR,ASF,OH7LZB-13:foo
FOO>BAR,DIGI1,qAR,ASD,OH7LZB-13,ASDF:foo
FOO>BAR,DIGI1,qAR,ASD,OH7LZB-135,ASDF:foo

client callsign after Q but not last:
user oh7lzb pass 20900
FOO>BAR,DIGI1,qAR,OH7LZB:foo
FOO>BAR,DIGI1,qAR,ASF,OH7LZB:foo
FOO>BAR,DIGI1,qAR,ASF,OH7LZB,ASDF:foo