Add initial unit tests for Provider

Largely cribbed from libhandy, thanks due to Guido.

tests/test-provider.c

@@ -0,0 +1,106 @@
+/*
+ * Copyright (C) 2018 Purism SPC
+ *
+ * SPDX-License-Identifier: GPL-3.0+
+ */
+
+#include "calls-dummy-provider.h"
+#include "calls-provider.h"
+#include "calls-origin.h"
+#include "calls-message-source.h"
+
+#include <gtk/gtk.h>
+#include <string.h>
+
+typedef struct {
+  CallsDummyProvider *dummy_provider;
+} Fixture;
+
+
+static void
+test_dummy_provider_set_up (Fixture *fixture,
+                            gconstpointer user_data)
+{
+  fixture->dummy_provider = calls_dummy_provider_new ();
+  calls_dummy_provider_add_origin (fixture->dummy_provider,
+                                   "Test origin 1");
+  calls_dummy_provider_add_origin (fixture->dummy_provider,
+                                   "Test origin 2");
+}
+
+
+static void
+test_dummy_provider_tear_down (Fixture *fixture,
+                               gconstpointer user_data)
+{
+  g_clear_object (&fixture->dummy_provider);
+}
+
+
+static void
+test_dummy_provider_object (Fixture *fixture,
+                            gconstpointer user_data)
+{
+  g_assert_true (G_IS_OBJECT (fixture->dummy_provider));
+  g_assert_true (CALLS_IS_MESSAGE_SOURCE (fixture->dummy_provider));
+  g_assert_true (CALLS_IS_PROVIDER (fixture->dummy_provider));
+}
+
+
+static void
+test_dummy_provider_get_name (Fixture *fixture,
+                              gconstpointer user_data)
+{
+  CallsProvider *provider;
+  const gchar *name;
+
+  provider = CALLS_PROVIDER (fixture->dummy_provider);
+
+  name = calls_provider_get_name (provider);
+  g_assert_nonnull (name);
+  g_assert_cmpuint (strlen (name), >, 0U);
+}
+
+
+static void
+test_dummy_provider_get_origins (Fixture *fixture,
+                                 gconstpointer user_data)
+{
+  GList *origins, *node;
+
+  origins = calls_provider_get_origins
+    (CALLS_PROVIDER (fixture->dummy_provider));
+
+  g_assert_cmpuint (g_list_length (origins), ==, 2);
+
+  for (node = origins; node; node = node->next)
+    {
+      g_assert_true (G_IS_OBJECT (node->data));
+      g_assert_true (CALLS_IS_ORIGIN (node->data));
+    }
+
+  g_list_free (origins);
+}
+
+
+gint
+main (gint   argc,
+      gchar *argv[])
+{
+  gtk_test_init (&argc, &argv, NULL);
+
+
+#define add_test(name)                                  \
+  g_test_add ("/Calls/Provider/" #name, Fixture, NULL,  \
+              test_dummy_provider_set_up,               \
+              test_dummy_provider_##name,               \
+              test_dummy_provider_tear_down);           \
+
+  add_test(object);
+  add_test(get_name);
+  add_test(get_origins);
+
+#undef add_test
+
+  return g_test_run();
+}