FIX: Homomorphism order method tests for finite domain.

This fixes gap-system#3097
ssiccha · Mar 27, 2019 · 4e018ef · 4e018ef
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diff --git a/lib/morpheus.gi b/lib/morpheus.gi
@@ -27,6 +27,9 @@ InstallMethod(Order,"for automorphisms",true,[IsGroupHomomorphism],0,
 function(hom)
 local map,phi,o,lo,i,j,start,img,d,nat,ser,jord,first;
   d:=Source(hom);
+  if not (HasIsFinite(d) and IsFinite(d)) then
+    TryNextMethod();
+  fi;
   if Size(d)<=10000 then
     ser:=[d,TrivialSubgroup(d)]; # no need to be clever if small
   else

diff --git a/tst/testbugfix/2018-12-11-fphomord.tst b/tst/testbugfix/2018-12-11-fphomord.tst
@@ -0,0 +1,5 @@
+# hom. order of infinite group in special case (fixing #3097)
+gap> f := FreeGroup(2);;
+gap> x := GroupHomomorphismByImages(f,f,[f.1,f.2],[f.2,f.1]);;
+gap> Order(x);
+2