A Note on Dependencies and Database Unit Testing

Ideas on unit testing for the database are often heavily influenced by the world of object oriented programming (OOP), usually Java in practice. This is no doubt because much of modern thinking on development methodologies, including test driven development (TDD), originated in this world. Some of these ideas appear to translate very well into the database world, including that of TDD itself, with automated unit tests. However, some ideas may not translate so well, or even make sense, in database unit testing. For example, Roy Osherove (2011), Unit Test – Definition says:

A good unit test … runs in memory (no DB or File access, for example)

One concept that appears very important in the OOP world is that of dependencies, and of isolation of the code under test from its dependencies. This gives rise to complex mechanisms of ‘mocking’ and ‘dependency injection’ to bring about said isolation. Osherove mentions isolation in the same article as a requirement of good unit testing, and his view appears to be widespread. It’s worth mentioning though that not everyone in the OOP world shares his insistence. The influential Martin Fowler (2014) uses a nice terminology of ‘sociable’ tests (as opposed to ‘isolated’ tests) for tests that rely on other units to fulfill the behaviour under test, and he uses this approach himself when practicable, UnitTest.

In the case of database unit testing, it seems to me to make very little sense to think in terms of isolating code under test from its dependencies. The following two diagrams represent how I see the relationships between base code, dependencies and unit test code across two distinct phases.

Development Phase
UT Phases-dev

Regression Phase
UT Phases-reg

I would welcome any comments or opinions.


A Template Script for JDBC Calling of Oracle Procedures with Object Array Parameters

Some time ago I wrote an Oracle database package for a web service. The Java developer for the service told me that it was throwing an error when called from Java, although I had unit tested it from PL/SQL. He gave me a small Java driver script to demonstrate the issue, and this allowed the issue to be quickly identified: As both Java and PL/SQL have boolean data types I had considered that a boolean parameter would make sense to pass a boolean value. However, it turns out that this does not work in JDBC, and so I replaced it with an integer parameter.

It occurred to me then that it would be nice if the database developer was able in general to test JDBC compatibility of his or her procedure as a final step after unit testing. To this end I created a more generic example script based on a simple procedure that I wrote against Oracle’s HR demo schema, the same procedure that I used as an example of a unit testing design pattern Design Patterns for Database Unit Testing 2: Web Service Saving – Code

Update, 4 November 2017: I have made a self-contained project on GitHub with both Java and Oracle code, avoiding dependency on my testing project. JDBC Calling of Oracle Procedures with Object Array Parameters on GitHub. I have also added the Oracle code below.

The code below runs against any Oracle instance in which the standard Oracle HR demo schema has been installed. There is a video demonstration of how to install and run it at the end of this article. The procedure has one input and one output object array parameter, and can easily be extended as desired. It requires one jar file in the classpath, ojdbc6.jar, which is available in Oracle client or database installations, and can be run from an IDE such as Eclipse.

Java Code

package jdbcdemo;
Name:        Driver.java
Description: This is a Java driver script for Brendan's HR demo web service procedure. It is
             designed to serve as a template for other web service procedures to allow a database
             developer to do a JDBC integration test easily, and can also be used as a starting point
             for Java development.

             The template procedure takes an input array of objects and has an output array of 
             objects. It is easy to update for any named object and array types, procedure and
             Oracle connection. Any other signature types would need additional changes.

	     See 'A Template Script for JDBC Calling of Oracle Procedures with Object Array Parameters'
A Template Script for JDBC Calling of Oracle Procedures with Object Array Parameters
Modification History Who When Which What -------------------- ----------- ----- ------------------------------------------------------------- Brendan Furey 14-May-2016 1.0 Created Brendan Furey 04-Nov-2017 1.1 Put into new GitHub project along with Oracle code ***************************************************************************************************/ import java.sql.DriverManager; import java.sql.SQLException; import java.sql.Array; import java.sql.Struct; import oracle.jdbc.OracleTypes; import oracle.jdbc.OracleCallableStatement; import oracle.jdbc.OracleConnection; public class Driver { // Change section 1/2: Replace these constants with your own values private static final String DB_CONNECTION = "jdbc:oracle:thin:hr/hr@localhost:1521/orclpdb"; private static final String TY_IN_OBJ = "TY_EMP_IN_OBJ"; private static final String TY_IN_ARR = "TY_EMP_IN_ARR"; private static final String TY_OUT_ARR = "TY_EMP_OUT_ARR"; private static final String PROC_NAME = "Emp_WS.AIP_Save_Emps"; private static OracleConnection conn; public static void main(String[] argv) { try { getDBConnection (); prOutArray (callProc (inArray ())); } catch (SQLException e) { System.out.println(e.getMessage()); } } private static Array inArray () throws SQLException { // Change section 2/2: Replace [2] with number of test records, and the arrays with their values Struct[] struct = new Struct[2]; struct[0] = conn.createStruct (TY_IN_OBJ, new Object[] {"LN 1", "EM 1", "IT_PROG", 1000}); struct[1] = conn.createStruct (TY_IN_OBJ, new Object[] {"LN 2", "EM 2", "IT_PROG", 2000}); return conn.createARRAY (TY_IN_ARR, struct); } private static Array callProc (Array objArray) throws SQLException { OracleCallableStatement ocs = (OracleCallableStatement) conn.prepareCall ("BEGIN "+PROC_NAME+"(:1, :2); END;"); ocs.setArray (1, objArray); ocs.registerOutParameter (2, OracleTypes.ARRAY, TY_OUT_ARR); ocs.execute (); return ocs.getARRAY (2); } private static void prOutArray (Array arr) throws SQLException { Object[] objArr = (Object[]) arr.getArray(); int j = 0; for (Object rec : objArr) { Object[] objLis = ((Struct)rec).getAttributes (); int i = 0; String recStr = ""; for (Object fld : objLis) { if (i++ > 0) recStr = recStr + '/'; recStr = recStr + fld.toString(); } System.out.println ("Record "+(++j)+": "+recStr); } } private static void getDBConnection () throws SQLException { conn = (OracleConnection) DriverManager.getConnection (DB_CONNECTION); conn.setAutoCommit (false); System.out.println ("Connected..."); } }

Example output


Google Java Style

Oracle Code


Author:      Brendan Furey
Description: Script to create objects to demo JDBC procedure calls with object array parameters

         See 'A Template Script for JDBC Calling of Oracle Procedures with Object Array Parameters'
A Template Script for JDBC Calling of Oracle Procedures with Object Array Parameters
Modification History Who When Which What -------------------- ----------- ----- ------------------------------------------------------------- Brendan Furey 04-May-2016 1.0 Created Brendan Furey 04-Nov-2017 1.1 Extracted the JDBC demo code from the unit testing project, and put into new GitHub project along with Java code ***************************************************************************************************/ REM Run this script from Oracle's standard HR schema to create objects to demo JDBC procedure calls COLUMN "Database" FORMAT A20 COLUMN "Time" FORMAT A20 COLUMN "Version" FORMAT A30 COLUMN "Session" FORMAT 9999990 COLUMN "OS User" FORMAT A10 COLUMN "Machine" FORMAT A20 SELECT 'Start: ' || dbs.name "Database", To_Char (SYSDATE,'DD-MON-YYYY HH24:MI:SS') "Time", Replace (Substr(ver.banner, 1, Instr(ver.banner, '64')-4), 'Enterprise Edition Release ', '') "Version" FROM v$database dbs, v$version ver WHERE ver.banner LIKE 'Oracle%'; PROMPT Input types creation DROP TYPE ty_emp_in_arr / CREATE OR REPLACE TYPE ty_emp_in_obj AS OBJECT ( last_name VARCHAR2(25), email VARCHAR2(25), job_id VARCHAR2(10), salary NUMBER ) / CREATE TYPE ty_emp_in_arr AS TABLE OF ty_emp_in_obj / PROMPT Output types creation DROP TYPE ty_emp_out_arr / CREATE OR REPLACE TYPE ty_emp_out_obj AS OBJECT ( employee_id NUMBER, description VARCHAR2(500) ) / CREATE TYPE ty_emp_out_arr AS TABLE OF ty_emp_out_obj / CREATE OR REPLACE PACKAGE Emp_WS AS /*************************************************************************************************** Description: HR demo web service code. Procedure saves new employees list and returns primary key plus same in words, or zero plus error message in output list ***************************************************************************************************/ PROCEDURE AIP_Save_Emps (p_ty_emp_in_lis ty_emp_in_arr, x_ty_emp_out_lis OUT ty_emp_out_arr); END Emp_WS; / CREATE OR REPLACE PACKAGE BODY Emp_WS AS PROCEDURE AIP_Save_Emps (p_ty_emp_in_lis ty_emp_in_arr, -- list of employees to insert x_ty_emp_out_lis OUT ty_emp_out_arr) IS -- list of employee results l_ty_emp_out_lis ty_emp_out_arr; bulk_errors EXCEPTION; PRAGMA EXCEPTION_INIT (bulk_errors, -24381); n_err PLS_INTEGER := 0; BEGIN FORALL i IN 1..p_ty_emp_in_lis.COUNT SAVE EXCEPTIONS INSERT INTO employees ( employee_id, last_name, email, hire_date, job_id, salary ) VALUES ( employees_seq.NEXTVAL, p_ty_emp_in_lis(i).last_name, p_ty_emp_in_lis(i).email, SYSDATE, p_ty_emp_in_lis(i).job_id, p_ty_emp_in_lis(i).salary ) RETURNING ty_emp_out_obj (employee_id, To_Char(To_Date(employee_id,'J'),'JSP')) BULK COLLECT INTO x_ty_emp_out_lis; EXCEPTION WHEN bulk_errors THEN l_ty_emp_out_lis := x_ty_emp_out_lis; FOR i IN 1 .. sql%BULK_EXCEPTIONS.COUNT LOOP IF i > x_ty_emp_out_lis.COUNT THEN x_ty_emp_out_lis.Extend; END IF; x_ty_emp_out_lis (SQL%Bulk_Exceptions (i).Error_Index) := ty_emp_out_obj (0, SQLERRM (- (SQL%Bulk_Exceptions (i).Error_Code))); END LOOP; FOR i IN 1..p_ty_emp_in_lis.COUNT LOOP IF i > x_ty_emp_out_lis.COUNT THEN x_ty_emp_out_lis.Extend; END IF; IF x_ty_emp_out_lis(i).employee_id = 0 THEN n_err := n_err + 1; ELSE x_ty_emp_out_lis(i) := l_ty_emp_out_lis(i - n_err); END IF; END LOOP; END AIP_Save_Emps; END Emp_WS; /

Here is a demo of installing and running the code, Oracle and Java:


Code Timing and Object Orientation and Zombies

This is a Word document that I wrote initially in November 2010 and uploaded to Scribd, Code Timing and Object Orientation and Zombies, with a big update in September 2012, about code timing in several languages.

I am going to upload a number of articles to this blog shortly that make use of an updated version of the Oracle code-timing package, and I am aware that many work networks disallow Scribd access, so I thought I would put it here first, Code Timing and Object Orientation and Zombies. It’s also embedded below (if that is accessible).

Here is the introduction:

This article proposes an object-oriented design for simple CPU and elapsed timing of computer programs by individual code section or subroutine. The object data structure is first described using a diagram/tabulation approach first used in A Perl Object for Flattened Master-Detail Data in Excel, followed by a section describing method usage, and including a diagram showing a typical call structure.

The object class is then translated from the Ur-language of design into the programming languages of Oracle, Perl and Java (one might say that our class of class is instantiated into specific object classes for each language). In each case the code is listed, an example driving program is briefly described, the run results are listed, and any interesting features are highlighted.

Oracle’s implementation of object-orientation is rather different from other languages, and a section of the article discusses how one can best obtain the advantages of object orientation in Oracle, suggesting that it’s often better to bypass the ‘official’ object structures. Both approaches have been implemented here to help readers judge for themselves.

Finally, some notes are collated on differences between the languages.