diff --git tests/phpunit/testcases/extend/buddypress/activity.php tests/phpunit/testcases/extend/buddypress/activity.php
new file mode 100644
index 0000000..bc1fad5
--- /dev/null
+++ tests/phpunit/testcases/extend/buddypress/activity.php
@@ -0,0 +1,236 @@
+<?php
+
+/**
+ * @group extend
+ * @group buddypress
+ * @group activity
+ */
+class BBP_Tests_Extend_BuddyPress_Activity extends BBP_UnitTestCase {
+
+	public function setUp() {
+		parent::setUp();
+
+		if ( ! function_exists( 'buddypress' ) ) {
+			return;
+		}
+	}
+
+	/**
+	 * Copied from `BBP_Forums_Group_Extension::new_forum()`.
+	 */
+	private function attach_forum_to_group( $forum_id, $group_id ) {
+		bbp_add_forum_id_to_group( $group_id, $forum_id );
+		bbp_add_group_id_to_forum( $forum_id, $group_id );
+	}
+
+	/**
+	 * @ticket BBP2794
+	 */
+	public function test_bp_activity_actions_for_site_wide_forum_topic() {
+		$u = $this->factory->user->create();
+		$f = $this->factory->forum->create();
+		$t = $this->factory->topic->create( array(
+			'post_parent' => $f,
+			'post_author' => $u,
+		) );
+
+		// Set up our activity text test string
+		$user_link       = bbp_get_user_profile_link( $u );
+		$topic_permalink = bbp_get_topic_permalink( $t );
+		$topic_title     = get_post_field( 'post_title',   $t, 'raw' );
+		$topic_content   = get_post_field( 'post_content', $t, 'raw' );
+		$topic_link      = '<a href="' . $topic_permalink . '">' . $topic_title . '</a>';
+		$forum_permalink = bbp_get_forum_permalink( $f );
+		$forum_title     = get_post_field( 'post_title', $f, 'raw' );
+		$forum_link      = '<a href="' . $forum_permalink . '">' . $forum_title . '</a>';
+		$activity_text   = sprintf( esc_html__( '%1$s started the topic %2$s in the forum %3$s', 'bbpress' ), $user_link, $topic_link, $forum_link );
+
+		// Create the activity
+		bbpress()->extend->buddypress->activity->topic_create( $t, $f, array(), $u );
+
+		$activity_id = (int) get_post_meta( $t, '_bbp_activity_id', true );
+		$activity = new BP_Activity_Activity( $activity_id );
+
+		$this->assertEquals( $activity_text, $activity->action );
+
+		// Are we dynamic?
+		wp_update_user( array( 'ID' => $u, 'display_name' => 'New Name', ) );
+		$user_link = bbp_get_user_profile_link( $u );
+
+		wp_update_post( array( 'ID' => $f, 'post_title' => 'New Forum Title', ) );
+		$forum_link = '<a href="' . $forum_permalink . '">New Forum Title</a>';
+
+		wp_update_post( array( 'ID' => $t, 'post_title' => 'New Topic Title', ) );
+		$topic_link = '<a href="' . $topic_permalink . '">New Topic Title</a>';
+
+		// Set up our new test string
+		$activity_text = sprintf( esc_html__( '%1$s started the topic %2$s in the forum %3$s', 'bbpress' ), $user_link, $topic_link, $forum_link );
+
+		$activity = new BP_Activity_Activity( $activity_id );
+
+		$this->assertEquals( $activity_text, $activity->action );
+	}
+
+	/**
+	 * @ticket BBP2794
+	 */
+	public function test_bp_activity_actions_for_reply_to_site_wide_forum_topic() {
+		$u = $this->factory->user->create();
+		$f = $this->factory->forum->create();
+		$t = $this->factory->topic->create( array(
+			'post_parent' => $f,
+			'post_author' => $u,
+		) );
+		$r = $this->factory->reply->create( array(
+			'post_parent' => $t,
+			'post_author' => $u,
+		) );
+
+		// Set up our activity text test string
+		$user_link       = bbp_get_user_profile_link( $u );
+		$topic_permalink = bbp_get_topic_permalink( $t );
+		$topic_title     = get_post_field( 'post_title',   $t, 'raw' );
+		$topic_content   = get_post_field( 'post_content', $t, 'raw' );
+		$topic_link      = '<a href="' . $topic_permalink . '">' . $topic_title . '</a>';
+		$forum_permalink = bbp_get_forum_permalink( $f );
+		$forum_title     = get_post_field( 'post_title', $f, 'raw' );
+		$forum_link      = '<a href="' . $forum_permalink . '">' . $forum_title . '</a>';
+		$activity_text   = sprintf( esc_html__( '%1$s replied to the topic %2$s in the forum %3$s', 'bbpress' ), $user_link, $topic_link, $forum_link );
+
+		// Create the activity
+		bbpress()->extend->buddypress->activity->reply_create( $r, $t, $f, array(), $u );
+
+		$activity_id = (int) get_post_meta( $r, '_bbp_activity_id', true );
+		$activity = new BP_Activity_Activity( $activity_id );
+
+		$this->assertEquals( $activity_text, $activity->action );
+
+		// Are we dynamic?
+		wp_update_user( array( 'ID' => $u, 'display_name' => 'New Name', ) );
+		$user_link = bbp_get_user_profile_link( $u );
+
+		wp_update_post( array( 'ID' => $f, 'post_title' => 'New Forum Title', ) );
+		$forum_link = '<a href="' . $forum_permalink . '">New Forum Title</a>';
+
+		wp_update_post( array( 'ID' => $t, 'post_title' => 'New Topic Title', ) );
+		$topic_link = '<a href="' . $topic_permalink . '">New Topic Title</a>';
+
+		// Set up our new test string
+		$activity_text = sprintf( esc_html__( '%1$s replied to the topic %2$s in the forum %3$s', 'bbpress' ), $user_link, $topic_link, $forum_link );
+
+		$activity = new BP_Activity_Activity( $activity_id );
+
+		$this->assertEquals( $activity_text, $activity->action );
+	}
+
+	/**
+	 * @ticket BBP2794
+	 */
+	public function test_bp_activity_actions_for_group_forum_topic() {
+		$g = $this->bp_factory->group->create();
+		$group = groups_get_group( array( 'group_id' => $g ) );
+		$u = $group->creator_id;
+		$f = $this->factory->forum->create();
+		$t = $this->factory->topic->create( array(
+			'post_parent' => $f,
+			'post_author' => $u,
+		) );
+		$r = $this->factory->reply->create( array(
+			'post_parent' => $t,
+			'post_author' => $u,
+		) );
+		$this->attach_forum_to_group( $f, $g );
+		buddypress()->groups->current_group = $group;
+
+		// Set up our activity text test string
+		$user_link       = bbp_get_user_profile_link( $u );
+		$topic_permalink = bbp_get_topic_permalink( $t );
+		$topic_title     = get_post_field( 'post_title', $t, 'raw' );
+		$topic_link      = '<a href="' . $topic_permalink . '">' . $topic_title . '</a>';
+		$forum_permalink = bbp_get_forum_permalink( $f );
+		$forum_title     = get_post_field( 'post_title', $f, 'raw' );
+		$forum_link      = '<a href="' . $forum_permalink . '">' . $forum_title . '</a>';
+		$activity_text   = sprintf( esc_html__( '%1$s started the topic %2$s in the forum %3$s', 'bbpress' ), $user_link, $topic_link, $forum_link );
+
+		// Create the activity
+		bbpress()->extend->buddypress->activity->topic_create( $t, $f, array(), $u );
+
+		$activity_id = (int) get_post_meta( $t, '_bbp_activity_id', true );
+		$activity = new BP_Activity_Activity( $activity_id );
+
+		$this->assertEquals( $activity_text, $activity->action );
+
+		// Are we dynamic?
+		wp_update_user( array( 'ID' => $u, 'display_name' => 'New Name', ) );
+		$user_link = bbp_get_user_profile_link( $u );
+
+		wp_update_post( array( 'ID' => $f, 'post_title' => 'New Forum Title', ) );
+		$forum_link = '<a href="' . $forum_permalink . '">New Forum Title</a>';
+
+		wp_update_post( array( 'ID' => $t, 'post_title' => 'New Topic Title', ) );
+		$topic_link = '<a href="' . $topic_permalink . '">New Topic Title</a>';
+
+		// Set up our new test string
+		$activity_text = sprintf( esc_html__( '%1$s started the topic %2$s in the forum %3$s', 'bbpress' ), $user_link, $topic_link, $forum_link );
+
+		$activity = new BP_Activity_Activity( $activity_id );
+
+		$this->assertEquals( $activity_text, $activity->action );
+	}
+
+	/**
+	 * @ticket BBP2794
+	 */
+	public function test_bp_activity_actions_for_reply_to_group_forum_topic() {
+		$g = $this->bp_factory->group->create();
+		$group = groups_get_group( array( 'group_id' => $g ) );
+		$u = $group->creator_id;
+		$f = $this->factory->forum->create();
+		$t = $this->factory->topic->create( array(
+			'post_parent' => $f,
+			'post_author' => $u,
+		) );
+		$r = $this->factory->reply->create( array(
+			'post_parent' => $t,
+			'post_author' => $u,
+		) );
+		$this->attach_forum_to_group( $f, $g );
+		buddypress()->groups->current_group = $group;
+
+		// Set up our activity text test string
+		$user_link       = bbp_get_user_profile_link( $u );
+		$topic_permalink = bbp_get_topic_permalink( $t );
+		$topic_title     = get_post_field( 'post_title',   $t, 'raw' );
+		$topic_content   = get_post_field( 'post_content', $t, 'raw' );
+		$topic_link      = '<a href="' . $topic_permalink . '">' . $topic_title . '</a>';
+		$forum_permalink = bbp_get_forum_permalink( $f );
+		$forum_title     = get_post_field( 'post_title', $f, 'raw' );
+		$forum_link      = '<a href="' . $forum_permalink . '">' . $forum_title . '</a>';
+		$activity_text   = sprintf( esc_html__( '%1$s replied to the topic %2$s in the forum %3$s', 'bbpress' ), $user_link, $topic_link, $forum_link );
+
+		// Create the activity
+		bbpress()->extend->buddypress->activity->reply_create( $r, $t, $f, array(), $u );
+
+		$activity_id = (int) get_post_meta( $r, '_bbp_activity_id', true );
+		$activity = new BP_Activity_Activity( $activity_id );
+
+		$this->assertEquals( $activity_text, $activity->action );
+
+		// Are we dynamic?
+		wp_update_user( array( 'ID' => $u, 'display_name' => 'New Name', ) );
+		$user_link = bbp_get_user_profile_link( $u );
+
+		wp_update_post( array( 'ID' => $f, 'post_title' => 'New Forum Title', ) );
+		$forum_link = '<a href="' . $forum_permalink . '">New Forum Title</a>';
+
+		wp_update_post( array( 'ID' => $t, 'post_title' => 'New Topic Title', ) );
+		$topic_link = '<a href="' . $topic_permalink . '">New Topic Title</a>';
+
+		// Set up our new test string
+		$activity_text = sprintf( esc_html__( '%1$s replied to the topic %2$s in the forum %3$s', 'bbpress' ), $user_link, $topic_link, $forum_link );
+
+		$activity = new BP_Activity_Activity( $activity_id );
+
+		$this->assertEquals( $activity_text, $activity->action );
+	}
+}
\ No newline at end of file