diff --git a/xCAT-test/unit/confluent_switch_retract.t b/xCAT-test/unit/confluent_switch_retract.t
new file mode 100644
index 000000000..8fbab7541
--- /dev/null
+++ b/xCAT-test/unit/confluent_switch_retract.t
@@ -0,0 +1,117 @@
+#!/usr/bin/env perl
+use strict;
+use warnings;
+
+use File::Spec;
+use FindBin;
+use Test::More;
+
+my $plugin = File::Spec->catfile( $FindBin::Bin, '..', '..',
+    'xCAT-server', 'lib', 'xcat', 'plugins', 'confluent.pm' );
+plan skip_all => 'confluent.pm not found' unless -r $plugin;
+
+open( my $fh, '<', $plugin ) or die "Unable to read $plugin: $!";
+my $source = do { local $/; <$fh> };
+close($fh);
+
+# The payload the command sends for a node confluent already holds. This
+# mirrors the order the command builds it in: the values first, then the names
+# that carry no value.
+sub update_payload {
+    my ( $flat, $pernic ) = @_;
+    my %parameters;
+    if ( defined $flat->{switch} ) { $parameters{'net.switch'}     = $flat->{switch} }
+    if ( defined $flat->{port} )   { $parameters{'net.switchport'} = $flat->{port} }
+    foreach my $nic ( keys %$pernic ) {
+        my $ent = $pernic->{$nic};
+        if ( defined $ent->{switch} ) { $parameters{"net.$nic.switch"}     = $ent->{switch} }
+        if ( defined $ent->{port} )   { $parameters{"net.$nic.switchport"} = $ent->{port} }
+    }
+    foreach my $topo ( 'net.switch', 'net.switchport' ) {
+        $parameters{$topo} = undef unless ( exists $parameters{$topo} );
+    }
+    $parameters{'net.*.switch'}     = undef;
+    $parameters{'net.*.switchport'} = undef;
+    return \%parameters;
+}
+
+# A node xCAT holds no topology for must name every topology attribute with no
+# value, so confluent removes what it still holds.
+my $p = update_payload( {}, {} );
+ok( exists $p->{'net.switch'},       'a node with no topology names the plain switch' );
+is( $p->{'net.switch'}, undef,       'the plain switch carries no value' );
+ok( exists $p->{'net.switchport'},   'a node with no topology names the plain port' );
+is( $p->{'net.switchport'}, undef,   'the plain port carries no value' );
+is( $p->{'net.*.switch'},     undef, 'every interface switch is named with no value' );
+is( $p->{'net.*.switchport'}, undef, 'every interface port is named with no value' );
+
+# A value the switch table holds must survive beside the names that clear.
+$p = update_payload( { switch => 'sw1', port => '1' }, {} );
+is( $p->{'net.switch'},     'sw1', 'a held plain switch keeps its value' );
+is( $p->{'net.switchport'}, '1',   'a held plain port keeps its value' );
+is( $p->{'net.*.switch'}, undef,   'the interface wildcard still clears' );
+
+# The interface case. Confluent removes what the wildcard matches before it
+# sets the rest of the request, so the current interface survives.
+$p = update_payload( {}, { ib0 => { switch => 'sw2', port => '9' } } );
+is( $p->{'net.ib0.switch'},     'sw2', 'the current interface keeps its switch' );
+is( $p->{'net.ib0.switchport'}, '9',   'the current interface keeps its port' );
+is( $p->{'net.*.switch'}, undef, 'the interface wildcard clears the rest' );
+is( $p->{'net.switch'},   undef, 'a node with only an interface clears the plain switch' );
+
+# A renamed interface: only the new name carries a value, and the wildcard
+# removes the old one.
+$p = update_payload( {}, { ens1f0 => { switch => 'sw3', port => '4' } } );
+is( $p->{'net.ens1f0.switch'}, 'sw3', 'the new interface name carries the switch' );
+ok( !exists $p->{'net.eth0.switch'}, 'the old interface name is not named on its own' );
+is( $p->{'net.*.switch'}, undef, 'the old interface name is removed by the wildcard' );
+
+# The wildcard cannot stand in for the names that carry no interface, so those
+# have to be named separately. This is why both forms are in the payload.
+SKIP: {
+    eval { require File::FnMatch; 1 }
+      or skip 'File::FnMatch not available', 1;
+    ok( !File::FnMatch::fnmatch( 'net.*.switch', 'net.switch' ),
+        'the interface wildcard does not match the plain name' );
+}
+# Same check without the optional module, using the rule the wildcard follows.
+ok( 'net.switch' !~ /^net\..+\.switch$/,
+    'the plain name needs its own clear because the wildcard cannot match it' );
+ok( 'net.ib0.switch' =~ /^net\..+\.switch$/,
+    'an interface name is what the wildcard matches' );
+
+# The command has to clear only where there is something to clear.
+my ($body) = $source =~ /\nsub donodeent \{(.*?)\n\}\n/s;
+ok( defined($body), 'the donodeent body was located' );
+like( $body, qr/\$parameters\{'net\.\*\.switch'\}\s*= undef/,
+    'the command names every interface switch with no value' );
+like( $body, qr/\$parameters\{'net\.\*\.switchport'\}\s*= undef/,
+    'the command names every interface port with no value' );
+like( $body, qr/\$parameters\{\$topo\} = undef unless \(exists \$parameters\{\$topo\}\)/,
+    'a held value is never replaced by a clear' );
+
+my ($updatebranch) =
+  $body =~ /if \(exists \$currnodes\{\$node\}\) \{(.*?)\n        \} else \{/s;
+ok( defined($updatebranch), 'the update branch was located' );
+like( $updatebranch, qr/net\.\*\.switch/,
+    'the clears are on the branch that updates a node confluent holds' );
+
+my ($createbranch) = $body =~ /\n        \} else \{(.*)$/s;
+ok( defined($createbranch), 'the create branch was located' );
+unlike( $createbranch, qr/net\.\*\.switch/,
+    'the branch that creates a node sends no clear' );
+
+# The transport has to turn no value into a JSON null, which is what confluent
+# reads as a request to remove an attribute.
+my $tlv = File::Spec->catfile( $FindBin::Bin, '..', '..',
+    'xCAT-server', 'lib', 'xcat', 'Confluent', 'TLV.pm' );
+SKIP: {
+    skip 'TLV.pm not found', 1 unless -r $tlv;
+    open( my $tf, '<', $tlv ) or die $!;
+    my $tsrc = do { local $/; <$tf> };
+    close($tf);
+    like( $tsrc, qr/\$self->\{json\}->utf8->encode\(\$data\)/,
+        'the payload is encoded as JSON, which carries no value as null' );
+}
+
+done_testing();