Add regular expression testing for user name mapping in the peer authentication TAP test

[Drouvot, Bertrand]

Hi hackers,

while working on [1], I thought it could also be useful to add regular 
expression testing for user name mapping in the peer authentication TAP 
test.

This kind of test already exists in kerberos/t/001_auth.pl but the 
proposed one in the peer authentication testing would probably be more 
widely tested.

Please find attached a patch proposal to do so.

[1]: 
https://www.postgresql.org/message-id/4f55303e-62c1-1072-61db-fbfb30bd66c8%40gmail.com

Looking forward to your feedback,

Regards,

--
Bertrand Drouvot
PostgreSQL Contributors Team
RDS Open Source Databases
Amazon Web Services: https://aws.amazon.comdiff --git a/src/test/authentication/t/003_peer.pl 
b/src/test/authentication/t/003_peer.pl
index fc951dea06..4e2efbe5e3 100644
--- a/src/test/authentication/t/003_peer.pl
+++ b/src/test/authentication/t/003_peer.pl
@@ -23,18 +23,34 @@ sub reset_pg_hba
        return;
 }
 
+# Delete pg_ident.conf from the given node, add a new entry to it
+# and then execute a reload to refresh it.
+sub reset_pg_ident
+{
+       my $node        = shift;
+       my $map_name    = shift;
+       my $system_user = shift;
+       my $pg_user     = shift;
+
+       unlink($node->data_dir . '/pg_ident.conf');
+       $node->append_conf('pg_ident.conf', "$map_name $system_user $pg_user");
+       $node->reload;
+       return;
+}
+
 # Test access for a single role, useful to wrap all tests into one.
 sub test_role
 {
        local $Test::Builder::Level = $Test::Builder::Level + 1;
 
-       my ($node, $role, $method, $expected_res, %params) = @_;
+       my ($node, $role, $method, $expected_res, $test_details, %params) = @_;
        my $status_string = 'failed';
        $status_string = 'success' if ($expected_res eq 0);
 
        my $connstr = "user=$role";
        my $testname =
-         "authentication $status_string for method $method, role $role";
+         "authentication $status_string for method $method, role $role "
+         . $test_details;
 
        if ($expected_res eq 0)
        {
@@ -87,16 +103,43 @@ my $system_user =
 # Tests without the user name map.
 # Failure as connection is attempted with a database role not mapping
 # to an authorized system user.
-test_role($node, qq{testmapuser}, 'peer', 2,
+test_role(
+       $node, qq{testmapuser}, 'peer', 2,
+       'without user name map',
        log_like => [qr/Peer authentication failed for user "testmapuser"/]);
 
 # Tests with a user name map.
-$node->append_conf('pg_ident.conf', qq{mypeermap $system_user testmapuser});
+reset_pg_ident($node, 'mypeermap', $system_user, 'testmapuser');
 reset_pg_hba($node, 'peer map=mypeermap');
 
 # Success as the database role matches with the system user in the map.
-test_role($node, qq{testmapuser}, 'peer', 0,
+test_role($node, qq{testmapuser}, 'peer', 0, 'with user name map',
        log_like =>
          [qr/connection authenticated: identity="$system_user" method=peer/]);
 
+# Test with regular expression in user name map.
+my $last_system_user_char = substr($system_user, -1);
+
+# The regular expression matches.
+reset_pg_ident($node, 'mypeermap', qq{/^.*$last_system_user_char\$},
+       'testmapuser');
+test_role(
+       $node,
+       qq{testmapuser},
+       'peer',
+       0,
+       'with regular expression in user name map',
+       log_like =>
+         [qr/connection authenticated: identity="$system_user" method=peer/]);
+
+# The regular expression does not match.
+reset_pg_ident($node, 'mypeermap', '/^$', 'testmapuser');
+test_role(
+       $node,
+       qq{testmapuser},
+       'peer',
+       2,
+       'with regular expression in user name map',
+       log_like => [qr/no match in usermap "mypeermap" for user 
"testmapuser"/]);
+
 done_testing();