Oracle deadlock test

create table test1 (a number(10), b number(10), CONSTRAINT test1_pk_demo PRIMARY KEY (a,b)); 
create table test2 (a number(10), b number(10), CONSTRAINT test2_pk_demo PRIMARY KEY (a,b)); 

insert into test1 values (1, 2); 
insert into test2 values (1, 2); 
commit; 

<sys session>
alter system set events '60 trace name systemstate level 258';

<session 1 > 
insert into test1 values (2, 3); 

<session 2 > 
update test2 set a=2,b=3 where a=1; 

<session 1 > 
update test2 set a=2,b=3 where a=1; 

<session 2 > 
insert into test1 values (2, 3); 


<sys session>
alter system set events '60 trace name context off';