tests: Add primitive contact tests

This makes sure that a NULL id will return a NULL contact and additionally
asserts that even a NULL contact will give us sensible primary/secondary display
information.

tests/test-contacts.c

@@ -0,0 +1,38 @@
+/*
+ * Copyright (C) 2022 Purism SPC
+ *
+ * SPDX-License-Identifier: GPL-3.0+
+ *
+ * Author: Evangelos Ribeiro Tzaras <evangelos.tzaras@puri.sm>
+ */
+
+#include "calls-best-match.h"
+#include "calls-contacts-provider.h"
+
+#include <gtk/gtk.h>
+
+static void
+test_contacts_null_contact (void)
+{
+  g_autoptr (CallsSettings) settings = calls_settings_new ();
+  g_autoptr (CallsContactsProvider) contacts_provider =
+    calls_contacts_provider_new (settings);
+  CallsBestMatch *best_match;
+
+  best_match = calls_contacts_provider_lookup_id (contacts_provider, NULL);
+  g_assert_null (best_match);
+
+  g_assert_cmpstr (calls_best_match_get_primary_info (best_match), ==, "Anonymous caller");
+  g_assert_cmpstr (calls_best_match_get_secondary_info (best_match), ==, "");
+}
+
+int
+main (int   argc,
+      char *argv[])
+{
+  gtk_test_init (&argc, &argv, NULL);
+
+  g_test_add_func ("/Calls/contacts/null", (GTestFunc) test_contacts_null_contact);
+
+  g_test_run ();
+}