DWBI Testing by Puneet

8/8/2019 DWBI Testing by Puneet

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Testing of a Reporting

Application

Data Centric Testing Approach

By Puneet Maheshwari


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Topics

Data Warehouse

Data Flow

BI

Report types

DW BI Testing

Report Testing

ETL Testing


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Data Warehouse

Data warehouse is a repository of an organization'selectronically stored data.

DW contains Subject oriented, Non volatile, Integratedand Time variant Data.

Data warehouses are designed to facilitate reporting andanalysis.

Data mart is a miniature data warehouse designed tomeet Reporting needs of specific department of BusinessFunction.


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A generalised DW System


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Generalized Data Flow

csv

Cube

DM

DB

SourceStaging

DW

ETL

ETL

ETL

ETL

ETL

Reports


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Data Warehouse Data model

DW Database is modeled on Star Schema orSnow flaked Schema.

Schema contain Fact and Dimension Tables.

Dimension Table contain the attributes ofmeasures or facts. This table contain primary(or surrogate keys).

Fact Tables contain Numeric measures andforeign keys to dimension Tables.


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BI Tool Structure

Tables

Semantic Layer Reports

RequestSQL

Data Formatted Data


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Semantic layer

This is a layer through which a user accessesdatabase.

Hides the complexity of underlying data sources. Allows data access using common business terms.

Creates Complex and efficient SQL statements.

It contains Metadata, Tables & Columns information,

Joins, Cardinality, Database connection, Users

Semantic layer is provided by BI tool.


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Types of Reports

Static Reports:Data is displayed in form of tables or charts.The data can be summarized or detailed.These reports have fixed layout and precisely defined

functionality.

User can only select filter values and prompt values.

Dash Boards:Single interface of many data.Data is generally displayed as graphical manner like pie

chart, bar graph, dials etc.

Dash boards are also used to display KPI of the system.


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Types of Reports

KPI/Score Card/Metric Reports:KPI- Key performance indicators are High level aggregations of data existing

in the system.

These reports show the KPI/Metric values with various colors based onperformance. e.g.: Heat chart report.

Adhoc reports:These reports are made on the fly by users.

These reports are made to analyze scenarios not covered in static reports.

Reports are made in Query Studio.

Cognos packages are exposed for users in query studio.


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BI/Report Testing


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BI/Report Testing

Format tests:

Header , Footer,

Look and feel, Fonts,

Static Prompts & Dynamic Prompts,

Conditional formatting, Paging. Functional Tests:

Checking all Functionalities of report,

Checking filters and their options,

Requirement conformance .


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BI/Report Testing

Data Validation: Most critical test in BI testing.

Fixed Reports:

Generate the Report.

SQL query is made as per functionality of report andfired at each data step.

(For cross tab reports if SQL gets very complicated,report can be broken from one dimension into manysub reports.)

Results of SQL query and Report are compared atrecord level.If result set is huge sampling can be performed.


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BI/Report Testing

Dash Bords/KPIs

Generate the report.

As per KPI Definition SQL Query is made and fired atdatabase.KPI values generated by SQL and Report are compared.

Color displays for Matrices are checked with standards.

Adhoc Reports (Cognos Model Testing):Static check of links between Query objects and Query Itemswith database tables and columns respectively.

Static Check of joins created between query objects.

Static checks are performed at report studio.Checking calculations and aggregations by running adhocreports and corresponding SQL Query in Database.


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BI/Report Testing

Performance Testing

Report Generation and Refresh duration.

Authentication and Security Testing

Only authorized users should get access toreports.

Scheduled reports should be delivered tocorrect inboxes.


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Pre Requisites for Report

testing Access rights. Report requirements i.e. Functionality.

Data models of reporting database.

KPI and Metric definitions.

Mapping between reports and databasetables.

Knowledge of SQL.


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ETL Testing


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ETL Testing

Data Completeness

To Test all jobs have run successfully and data transfer iscomplete.

Counts between two data holding stages should be equal.

Aggregations on numeric columns should be equal.


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ETL Testing

Data Correctness

Also called as Transformation Testing

Validation of business rules.

Business rules are documented as mappingdocuments.

A sample Mapping

Source Target

DB Table Coulmn DataType DB Table Coulmn DataType Transformation

Scr TblX A int Tgt TblX P int A + 100

Scr TblX B CHAR Tgt TblX Q Date Date(B)

Scr TblY C int Tgt TblX R int Sum( C )

TblX S int Default 100


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ETL Testing

Data Correctness Testing

Attribute level transformation validation process.

A select SQL Query, containing key columns + attribute columns, isfired at target table.

ETL is executed.

A SQL query , containing source columns + transformations(sourcecolumn), is fired on source table.

The results are compared.

This comparison is performed for small subset of data.

All attributes should be validated in one or more queries.


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ETL Testing

Data Correctness Testing

Each Types of transformations needs separate validation.

Aggregations

Direct Maps

Defaults

Lookups

Calculations

DFD,LDM &ERD are required to formulate filter conditions

and joins in the SQL query.


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ETL Testing

Data Validation

Row to Row comparison between twoconsecutive data holding stages.

A small set of test data is prepared and ETL isexecuted to load it.

SQL query are used to validate complete

data at each stage.


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ETL Testing

Environment Integration

Testing ETL execution on various OS , DBetc.

Testing Logging mechanism of ETLs.

Execution Logs

Error Logs

Data Rejection logs Testing ETL on schedulers.


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Pre Requisites for ETL Testing

Mappings between each stage.

Data Flow Diagram, Logical data modeland Physical data models.

Database access rights and ETLexecution rights.

Knowledge of SQL, Operating systemcommands and ETL Tool used.


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Other DW Tests

System Reconciliations.

Comparison of DW Reports with otherreporting applications.

Automation of ETL Testing.

Testing of Landing server files.

DWBI Testing by Puneet

Documents

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