wip: cover unset query context (#1723)

Author: superdav42

tests/WP_Ultimo/Multiple_Accounts_Compat_Test.php

@@ -37,6 +37,26 @@ public function test_fix_user_query_tolerates_null_func_call(): void {
 		}
 	}
 
+	/**
+	 * Test user query filter tolerates an unset wpdb function call context.
+	 */
+	public function test_fix_user_query_tolerates_unset_func_call(): void {
+
+		global $wpdb;
+
+		$func_call = $wpdb->func_call ?? null;
+
+		unset($wpdb->func_call);
+
+		$query = 'SELECT * FROM wp_users';
+
+		try {
+			$this->assertSame($query, \WP_Ultimo\Compat\Multiple_Accounts_Compat::get_instance()->fix_user_query($query));
+		} finally {
+			$wpdb->func_call = $func_call;
+		}
+	}
+
 	/**
 	 * Test unrelated user columns tolerate null output from earlier filters.
 	 */