testing: Use local tcp session for DBus to avoid leftover socket files

data/test-dbus.conf

@@ -0,0 +1,15 @@
+<!DOCTYPE busconfig PUBLIC "-//freedesktop//DTD D-Bus Bus Configuration 1.0//EN"
+ "http://www.freedesktop.org/standards/dbus/1.0/busconfig.dtd">
+<busconfig>
+  <type>session</type>
+  <keep_umask/>
+  <listen>tcp:host=localhost,port=0</listen>
+  <auth>EXTERNAL</auth>
+  <auth>ANONYMOUS</auth>
+  <allow_anonymous/>
+  <policy context="default">
+    <allow send_destination="*" eavesdrop="true"/>
+    <allow eavesdrop="true"/>
+    <allow own="*"/>
+  </policy>
+</busconfig>

src/testing.rs

@@ -112,7 +112,7 @@ pub struct TestHandle {
 impl MockDBus {
     pub async fn new() -> Result<MockDBus> {
         let mut process = Command::new("/usr/bin/dbus-daemon")
-            .args(["--session", "--nofork", "--print-address"])
+            .args(["--nofork", "--print-address", "--config-file=data/test-dbus.conf"])
             .stdout(Stdio::piped())
             .spawn()?;