diff --git a/t/01-idle_xact.t b/t/01-idle_xact.t
new file mode 100644
index 0000000..4b60969
--- /dev/null
+++ b/t/01-idle_xact.t
@@ -0,0 +1,194 @@
+#!/usr/bin/perl
+# This program is open source, licensed under the PostgreSQL License.
+# For license terms, see the LICENSE file.
+#
+# Copyright (C) 2012-2022: Open PostgreSQL Monitoring Development Group
+
+use strict;
+use warnings;
+
+use lib 't/lib';
+use pgNode;
+use pgSession;
+use Test::More tests => 40;
+
+my $node = pgNode->get_new_node('prod');
+my $proc;
+
+$node->init;
+$node->start;
+
+### Begin of tests ###
+
+# failing without thresholds
+$node->command_checks_all( [
+    './check_pgactivity', '--service'  => 'oldest_idlexact',
+                          '--username' => getlogin,
+                          '--format'   => 'human'
+    ],
+    127,
+    [ qr/^$/ ],
+    [ qr/^FATAL: you must specify critical and warning thresholds.$/m ],
+    'failing without thresholds'
+);
+
+# Tests for PostreSQL 8.2 and before
+SKIP: {
+    skip "testing incompatibility with PostgreSQL 8.2 and before", 3
+        if $node->version >= 8.3;
+
+    $node->command_checks_all( [
+        './check_pgactivity', '--service'  => 'oldest_idlexact',
+                              '--username' => getlogin,
+                              '--format'   => 'human',
+                              '--warning'  => '30s',
+                              '--critical' => '1h'
+        ],
+        1,
+        [ qr/^$/ ],
+        [ qr/^Service oldest_idlexact is not compatible with host/ ],
+        'non compatible PostgreSQL version'
+    );
+}
+
+SKIP: {
+    skip "incompatible tests with PostgreSQL < 8.3", 34 if $node->version < 8.3;
+
+    # basic check
+    $node->command_checks_all( [
+        './check_pgactivity', '--service'  => 'oldest_idlexact',
+                              '--username' => getlogin,
+                              '--format'   => 'human',
+                              '--dbname'   => 'template1',
+                              '--warning'  => '30s',
+                              '--critical' => '1h'
+        ],
+        0,
+        [ qr/^Service  *: POSTGRES_OLDEST_IDLEXACT$/m,
+          qr/^Returns  *: 0 \(OK\)$/m,
+          qr/^Message  *: 0 idle transaction\(s\)$/m,
+          qr/^Perfdata *: template1 # idle xact=0$/m
+        ],
+        [ qr/^$/ ],
+        'basic check'
+    );
+
+    # unit check
+    $node->command_checks_all( [
+        './check_pgactivity', '--service'  => 'oldest_idlexact',
+                              '--username' => getlogin,
+                              '--format'   => 'human',
+                              '--dbname'   => 'template1',
+                              '--warning'  => '30m',
+                              '--critical' => '1h'
+        ],
+        0,
+        [ qr/^Service  *: POSTGRES_OLDEST_IDLEXACT$/m,
+          qr/^Perfdata       : template1 avg=NaNs warn=1800 crit=3600$/m,
+        ],
+        [ qr/^$/ ],
+        'unit check'
+    );
+
+    $proc = pgSession->new( $node, 'postgres' );
+
+    $proc->query( 'BEGIN', 1 );
+    $proc->query( 'SELECT txid_current()', 1 );
+
+    # OK check
+    $node->command_checks_all( [
+        './check_pgactivity', '--service'  => 'oldest_idlexact',
+                              '--username' => getlogin,
+                              '--format'   => 'human',
+                              '--dbname'   => 'postgres',
+                              '--warning'  => '3s',
+                              '--critical' => '1h'
+        ],
+        0,
+        [ qr/^Service  *: POSTGRES_OLDEST_IDLEXACT$/m,
+          qr/^Returns  *: 0 \(OK\)$/m,
+          qr/^Message  *: 1 idle transaction\(s\)$/m,
+          qr/^Perfdata *: postgres # idle xact=1$/m
+        ],
+        [ qr/^$/ ],
+        'OK check'
+    );
+
+    # wait for transaction to be idle for more than 3 seconds
+    $node->poll_query_until( 'template1', q{
+        SELECT current_timestamp - xact_start > interval '3s'
+        FROM pg_catalog.pg_stat_activity
+        WHERE datname = 'postgres'
+          AND xact_start IS NOT NULL
+        LIMIT 1
+    });
+
+    # warning check
+    $node->command_checks_all( [
+        './check_pgactivity', '--service'  => 'oldest_idlexact',
+                              '--username' => getlogin,
+                              '--format'   => 'human',
+                              '--dbname'   => 'postgres',
+                              '--warning'  => '2s',
+                              '--critical' => '1h'
+        ],
+        1,
+        [ qr/^Service  *: POSTGRES_OLDEST_IDLEXACT$/m,
+          qr/^Returns  *: 1 \(WARNING\)$/m,
+          qr/^Message  *: 1 idle transaction\(s\)$/m,
+          qr/^Perfdata *: postgres # idle xact=1$/m
+        ],
+        [ qr/^$/ ],
+        'warning check'
+    );
+
+    # critical check
+    $node->command_checks_all( [
+        './check_pgactivity', '--service'  => 'oldest_idlexact',
+                              '--username' => getlogin,
+                              '--format'   => 'human',
+                              '--dbname'   => 'template1',
+                              '--warning'  => '1s',
+                              '--critical' => '2s'
+        ],
+        2,
+        [ qr/^Service  *: POSTGRES_OLDEST_IDLEXACT$/m,
+          qr/^Returns  *: 2 \(CRITICAL\)$/m,
+          qr/^Message  *: 1 idle transaction\(s\)$/m,
+          qr/^Perfdata *: postgres # idle xact=1$/m
+        ],
+        [ qr/^$/ ],
+        'critical check'
+    );
+
+    SKIP: {
+        skip "active xact are not detected before 9.2", 6 if $node->version < 9.2;
+
+        # Emit one query and check that check_pga does not emit a warning or critical
+        $proc->query( 'SELECT count(*) FROM pg_class', 1 );
+
+        # active transaction check
+        $node->command_checks_all( [
+            './check_pgactivity', '--service'  => 'oldest_idlexact',
+                                  '--username' => getlogin,
+                                  '--format'   => 'human',
+                                  '--dbname'   => 'template1',
+                                  '--warning'  => '2s',
+                                  '--critical' => '1h'
+            ],
+            0,
+            [ qr/^Service  *: POSTGRES_OLDEST_IDLEXACT$/m,
+              qr/^Returns  *: 0 \(OK\)$/m,
+              qr/^Message  *: 1 idle transaction\(s\)$/m,
+              qr/^Perfdata *: postgres # idle xact=1$/m
+            ],
+            [ qr/^$/ ],
+            'active transaction check'
+        );
+    }
+}
+
+### End of tests ###
+
+# stop immediate to kill any remaining backends
+$node->stop( 'immediate' );
diff --git a/t/lib/pgSession.pm b/t/lib/pgSession.pm
index b7f06ff..c7348c4 100644
--- a/t/lib/pgSession.pm
+++ b/t/lib/pgSession.pm
@@ -20,10 +20,15 @@ sub new {
     $db = 'template1' unless defined $db;
 
     $self->{'timer'} = IPC::Run::timer(5);
+    $self->{'delim'} = 'CHECK_PGA_PROMPT_DELIM=>';
     $self->{'in'}    = '';
     $self->{'out'}   = '';
     $self->{'proc'}  = $node->interactive_psql(
-        $db, \$self->{'in'}, \$self->{'out'}, $self->{'timer'}
+        $db, \$self->{'in'}, \$self->{'out'}, $self->{'timer'},
+        extra_params=>[
+            '--pset=pager',
+            '--variable=PROMPT1='. $self->{'delim'}
+        ]
     );
 
     return bless $self, $class;
@@ -33,8 +38,20 @@ sub query {
     my ($self, $q, $t) = @_;
 
     $self->{'out'} = '';
-    $self->{'in'}  .= "$q;\n";
+    $self->{'in'} = '';
+
     $self->{'timer'}->start($t);
+
+    # wait for the prompt to appear
+    $self->{'proc'}->pump until $self->{'out'} =~ $self->{'delim'};;
+
+    # reset the output to forget the banner + prompt
+    $self->{'out'} = '';
+
+    # write and run the query (this echoes the query in $out :/)
+    $self->{'in'}  .= "$q;\n";
+
+    # push $in to the procs
     $self->{'proc'}->pump while length $self->{'in'};
 }