From 77185ba00ecac56583d6ee59ee4d147bbbee8a41 Mon Sep 17 00:00:00 2001
From: Steve Linton <steve.linton@st-andrews.ac.uk>
Date: Sat, 4 May 2019 14:51:24 +0100
Subject: [PATCH] Test

---
 tst/testinstall/opers/SubdirectProduct.tst | 26 ++++++++++++++++++++++
 1 file changed, 26 insertions(+)
 create mode 100644 tst/testinstall/opers/SubdirectProduct.tst

diff --git a/tst/testinstall/opers/SubdirectProduct.tst b/tst/testinstall/opers/SubdirectProduct.tst
new file mode 100644
index 00000000000..aeaa7dd10fb
--- /dev/null
+++ b/tst/testinstall/opers/SubdirectProduct.tst
@@ -0,0 +1,26 @@
+gap> START_TEST("SubdirectProduct.tst");
+gap> f:=FreeGroup("a", "b");;
+gap> g:=f/[ f.1^6, f.2^4, f.1^3*f.2^(-2), f.2^(-1)*f.1*f.2*f.1];;
+gap> Size(g);
+12
+gap> g0:=Subgroup(g, [g.1^2]);;
+gap> g1:=g/g0;;
+gap> ff:=FreeGroup("c");;
+gap> h:=ff/[ff.1^12];;
+gap> Size(h);
+12
+gap> h0:=Subgroup(h,[h.1^4]);;
+gap> h1:=h/h0;;
+gap> ng:=NaturalHomomorphismByNormalSubgroup(g,g0);;
+gap> nh:=NaturalHomomorphismByNormalSubgroup(h,h0);;
+gap> phi:=IsomorphismGroups(g1,h1);;
+gap> ghom:=CompositionMapping(phi, ng);;
+gap> hhom:=nh;;
+gap> nn:=SubdirectProduct(g,h,ghom,hhom);;
+gap> Size(nn);
+36
+gap> Projection(nn,1);
+[ f1, f2, f3, f4 ] -> [ b, a^9, a^4, <identity ...> ]
+gap> Projection(nn,2);
+[ f1, f2, f3, f4 ] -> [ c^9, c^6, <identity ...>, c^4 ]
+gap> STOP_TEST("SubdirectProduct.tst", 10000);