Database testing

             

                                     Happy testing....!

                                 

Database testing involves the retrieved values from the database by the web or desktop application. Data in the User Interface should be matched as per the records are stored in the database.
 
                                            

Database Testing Validations

The following verifications are carried out during database testing:

• Checking the data Mapping.
• ACID (Atomicity, Consistency, Isolation, Durability) properties validation.
• Data Integrity
• Business rule conformance

1) Data Mapping: In software systems, data often travels back and forth from the UI (user interface) to the backend DB and vice versa. So these are some aspects to watch for:

• Check whether the fields in the UI/front end forms are mapped consistently with the corresponding fields in the DB table.  Typically this mapping information is defined in the requirements documents.
• Whenever a certain action is performed in the front end of an application, a corresponding CRUD (Create, Retrieve, Update and Delete) action gets invoked at the back end. A tester will have to check if the right action is invoked and whether the invoked action in itself is successful or not.

2) ACID properties validation:  Atomicity, Consistency, Isolation and Durability. Every transaction a DB performs has to adhere to these four properties. (image credit)

• Atomicity means that a transaction either fails or passes. This means that even if a single part of a transaction fails- it means that the entire transaction has failed. Usually this is called the “all-or nothing” rule.
• Consistency: A transaction will always result in a valid state of the DB
• Isolation: If there are multiple transactions a
• nd they are executed all at once, the result/state of the DB should be the same as if they were executed one after the other.
• Durability: Once a transaction is done and committed, no external factors like power loss or crash should be able to change it

3) Data integrity:
This means that following any of the CRUD operations, the updated and most recent values/status of shared data should appear on all the forms and screens. A value should not be updated on one screen and display an older value on another one. So devise your DB test cases in a way to include checking the data in all the places it appears to see if it is consistently the same.

4) Business rule conformity:  More complexity in databases means more complicated components like relational constraints, triggers, stored procedures, etc. So testers will have to come up with appropriate SQL queries in order to validate these complex objects.

How to test – Database Testing Process

The general test process for DB testing is not very different from any other application. The following are the steps:
Step #1) Prepare the environment
Data control language: Deals with giving authorization to users for manipulation and access to the data. Grant and Revoke are the two statements used.
Grant syntax:
Grant select/update
On <table name>
To <user id1, user id2…useridn>;
Revoke syntax:
Revokeselect/update
on <table name>
from<user id1, user id2…useridn>;

What to test – different components

1) Transactions:
When testing transactions it is important to make sure that they satisfy the ACID properties.
These are the statements commonly used:

• BEGIN TRANSACTION TRANSACTION#
• END TRANSACTION TRANSACTION#

The Rollback statement ensures that the database remains in a consistent state.

• ROLLBACK TRANSACTION#

After these statements are executed, use a Select to make sure the changes have been reflected.

• SELECT * FROM TABLENAME <tables which involve the transactions>

2) Database schema:
A database schema is nothing more than a formal definition of the how the data is going to be organized inside a DB. To test it:

• Identify the requirements based on which the database operates. Sample requirements:
  • Primary keys to be created before any other fields are created.
  • Foreign keys should be completely indexed for easy retrieval and searching.
  • Field names starting or ending with certain characters.
  • Fields with a constraint that certain values can or cannot be inserted.
• Use one of the following methods according to the relevance:
  • SQL Query DESC<table name> to validate the schema.
  • Regular expressions for validating the names of the individual fields and their values
  • Tools like SchemaCrawler

3) Trigger:
When a certain event takes places on a certain table, a piece of code (a trigger) can be auto-instructed to be executed.
For example, a new student joined a school. The student is taking 2 classes: math and science. The student is added to the “student table”.  A trigger could add the student to the corresponding subject tables once he is added to the student table.
The common method to test is to execute the SQL query embedded in the trigger independently first and record the result. Follow this up with executing the trigger as a whole. Compare the results.
These are tested during both the black box and white box testing phases.

• White box testing:  Stubs and drivers are used to insert or update or delete data that would result in the trigger being invoked. The basic idea is to just test the DB alone even before the integration with the front end (UI) is made.
• Black box testing:
  Step #2) Run a test
  Step #3) Check test result
  Step #4) Validate according to the expected results
  Step #5) Report the findings to the respective stakeholders

Usually, SQL queries are used to develop the tests. The most commonly used command is “Select”.
Select * from <tablename> where <condition>
Apart from Select, SQL has 3 important types of commands:

1. DDL : Data definition language
2. DML: Data manipulation language
3. DCL: Data control language

Let us see the syntax for the most commonly used statements.
Data Definition language: Uses CREATE, ALTER, RENAME, DROP and TRUNCATE to handle tables (and indexes).
Data Manipulation language: Includes statements to add, update and delete records.

a) Since the UI and DB integration is now available; we can insert/delete/update data from the front end in a way that the trigger gets invoked. Following that, Select statements can be used to retrieve the DB data to see if the trigger was successful in performing the intended operation.

b) The second way to test this is to directly load the data that would invoke the trigger and see if it works as intended.

4) Stored Procedures:
Stored procedures are more or less similar to user defined functions. These can be invoked by Call Procedure/Execute Procedure statements and the output is usually in the form of result sets.
These are stored in the RDBMS and are available for applications.
These are also tested during:

• White box testing: Stubs are used to invoke the stored procedures and then the results are validated against the expected values.
• Black box testing: Perform an operation from the front end (UI) of the application and check for the execution of the stored procedure and its results.

5) Field constraints – Default value, unique value and foreign key:

• Perform a front end operation which exercises the database object condition
• Validate the results with a SQL Query.

Checking the default value for a certain field is quite simple. It is part of business rule validation. You can do it manually or you can use tools like QTP. Manually, you can perform an action that will add a value other than the default value into the field from the front end and see if it results in an error.
The following is a sample VBScript code:

Function VBScriptRegularexpressionvlaidation(pattern , string_to_match)
Set newregexp = new RegExp
newregexp.Pattern = “<Default value as required by the business requirements>”
newregexp.Ignorecase = True
newregexp.Global = True
VBScriptRegularexpressionvlaidation = newregexp.Test(string_to_match)
End Function
Msgbox VBScriptRegularexpressionvlaidation(pattern , string_to_match)

The result of the above code is True if the default value exists or False if it doesn’t.
Checking the unique value can be done exactly the way we did for the default values. Try entering values from the UI that will violate this rule and see if an error is displayed.
Automation VB script code can be:

Function VBScriptRegularexpressionvlaidation(pattern , string_to_match)
Set newregexp = new RegExp
newregexp.Pattern = “<Unique value as required by the business requirements>”
newregexp.Ignorecase = True
newregexp.Global = True
VBScriptRegularexpressionvlaidation = newregexp.Test(string_to_match)
End Function
Msgbox VBScriptRegularexpressionvlaidation(pattern , string_to_match)

For the foreign key constraint validation use data loads that directly input data which violate the constraint and see if the application restricts them or not. Along with the back end data load, perform the front end UI operations too in a way that will violate the constraints and see if the relevant error is displayed.

Conclusion:

With all these features, factors and processes to test on a database, there is an increasing demand on the tester to be technically proficient in the key DB concepts. Despite some of the negative beliefs that DB testing creates new bottlenecks and is a lot of additional expenditure – this is a realm of testing that is attracting significant attention and demand.