Add method for asserting a table exists

src/db.py

@@ -1,11 +1,24 @@
 from mysql.connector.abstracts import MySQLConnectionAbstract
+from mysql.connector.cursor import MySQLCursorAbstract
 
+import exception
 from clui import log
 
+SHOW_TABLES = "SHOW TABLES"
+
 
 def test_connection(cnx: MySQLConnectionAbstract) -> None:
     log("Testing database connection")
     if cnx.is_connected():
         log(f"Successfully connected to MySQL {cnx.get_server_info()} on {cnx.server_host}.")
     else:
         log("Connection not working!")
+
+
+def assert_table_exists(cursor: MySQLCursorAbstract, table: str) -> None:
+    cursor.execute(SHOW_TABLES)
+    tables = cursor.fetchall()
+    for row in tables:
+        if table in row:
+            return
+    raise exception.TableNotFoundError(table)

src/exception.py

@@ -0,0 +1,9 @@
+class Error(Exception):
+    def __init__(self, message: str):
+        self.msg = message
+
+
+class TableNotFoundError(Error):
+    def __init__(self, table: str):
+        message = f"Could not find table {table}"
+        super().__init__(message)