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Unit Testing Legacy Code in Java SE 8

Untested code can be difficult and risky to maintain. This course will teach you techniques to get existing code under test as you work on it, without risky rewrites or redesigns.

One of the biggest challenges developers encounter in their career is having to maintain an existing codebase with little or no tests and unclear, tangled code. In this course, Unit Testing Legacy Code in Java, you will learn techniques to get a legacy and untested Java application, a small but realistic Java application to provide services to a hospital emergency room, under test incrementally as you work on it. First, you will learn about different types of tests and test doubles that can be applied to create a safety net for the application gradually. Next, you will discover crucial dependency-breaking techniques that will allow you to create seams to provide test doubles without disrupting the code. Finally, you will explore ways to deal with hard to understand code, improving the clarity as you work, and techniques to leverage new, tested code from hard to understand code. When you are finished with this course, you will have the knowledge to efficiently handle untested systems you’ve become responsible for.

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What's inside

Syllabus

Course Overview

Introducing Our Legacy System

Understanding the Role of Different Types of Tests

Testing Code with Problematic Dependencies

Testing Hard to Understand Code

Expanding Your Skills

Good to know

Know what's good

, what to watch for

, and possible dealbreakers

Introduces concepts crucial for maintaining software, such as testing, test doubles, and dependency breaking, which are standard in the software development industry

Taught by Jim Weaver, who is an experienced industry professional and instructor in software development

Examines real-world challenges faced by software developers, such as maintaining existing codebases with little to no documentation or testing

Provides hands-on practice to help learners apply the concepts of testing legacy and untested code in Java

Covers different types of testing, including unit testing, integration testing, and system testing

Students should come in with a basic understanding of Java programming and experience in software development

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Activities

Be better prepared before your course. Deepen your understanding during and after it. Supplement your coursework and achieve mastery of the topics covered in Unit Testing Legacy Code in Java SE 8 with these activities:

Read 'Clean Code' by Robert C. Martin

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Gain valuable insights into best practices for writing clean, maintainable, and testable code.

View CLEAN CODE on Amazon

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Read Chapter 7: Unit Testing.
Apply the principles of clean code to your unit testing practices.

Review Unit Testing Fundamentals

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Revisit the basics of unit testing to strengthen your understanding before delving into legacy code.

Browse courses on Unit Testing

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Review core concepts of unit testing, such as test cases, assertions, and coverage.
Explore different types of unit tests (e.g., black-box, white-box).

Test Driven Development (TDD) Exercise

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Practice writing unit tests before implementing code to gain a deeper understanding of its functionality.

Browse courses on Test Driven Development

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Start by defining test cases for a specific feature or method.
Write failing tests to drive the development of the feature or method.
Implement the code to pass the failing tests.

Three other activities

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Follow Along with a Dependency Injection Tutorial

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Learn how to use dependency injection to simplify testing and improve maintainability.

Browse courses on Dependency Injection

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Find a beginner-friendly tutorial on dependency injection in Java.
Follow the steps and implement the techniques in a small sample project.

Participate in a Unit Testing Study Group

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Engage with peers to discuss concepts, share experiences, and provide mutual support in understanding unit testing.

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Join or form a study group with other students taking the course.
Meet regularly to discuss unit testing concepts and practices.
Work together to solve problems and clarify misunderstandings.

Create Unit Tests for an Existing Java Module

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Apply your knowledge to a real-world project by writing unit tests for an existing Java module with minimal dependencies.

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Choose a small, well-defined Java module with limited dependencies.
Identify the key functionalities and use cases of the module.
Write unit tests that cover various scenarios and edge cases.
Run the tests and debug any failures to ensure proper functionality.

Career center

Learners who complete Unit Testing Legacy Code in Java SE 8 will develop knowledge and skills that may be useful to these careers:

Software Developer

As a Software Developer, you will be responsible for designing, developing, and maintaining software applications. This course will help you build a foundation in unit testing, which is an essential skill for Software Developers. You will learn techniques to test legacy code, which is often difficult to test due to its complexity and lack of documentation. This course will also teach you how to create test doubles, which are objects that simulate the behavior of other objects, allowing you to test code without disrupting the production environment.

See salaries and explore the career path for Software Developer

Quality Assurance Analyst

As a Quality Assurance Analyst, you will be responsible for ensuring the quality of software products by identifying and resolving defects. This course will help you build a foundation in unit testing, which is a crucial skill for Quality Assurance Analysts. You will learn techniques to test legacy code, which is often difficult to test due to its complexity and lack of documentation. This course will also teach you how to create test doubles, which are objects that simulate the behavior of other objects, allowing you to test code without disrupting the production environment.

See salaries and explore the career path for Quality Assurance Analyst

Software Test Engineer

As a Software Test Engineer, you will be responsible for designing and executing test plans to ensure the quality of software products. This course will help you build a foundation in unit testing, which is a crucial skill for Software Test Engineers. You will learn techniques to test legacy code, which is often difficult to test due to its complexity and lack of documentation. This course will also teach you how to create test doubles, which are objects that simulate the behavior of other objects, allowing you to test code without disrupting the production environment.

See salaries and explore the career path for Software Test Engineer

Software Architect

As a Software Architect, you will be responsible for designing and developing software architectures. This course will help you build a foundation in unit testing, which is an essential skill for Software Architects. You will learn techniques to test legacy code, which is often difficult to test due to its complexity and lack of documentation. This course will also teach you how to create test doubles, which are objects that simulate the behavior of other objects, allowing you to test code without disrupting the production environment.

See salaries and explore the career path for Software Architect

Technical Lead

As a Technical Lead, you will be responsible for leading and mentoring software development teams. This course will help you build a foundation in unit testing, which is an essential skill for Technical Leads. You will learn techniques to test legacy code, which is often difficult to test due to its complexity and lack of documentation. This course will also teach you how to create test doubles, which are objects that simulate the behavior of other objects, allowing you to test code without disrupting the production environment.

See salaries and explore the career path for Technical Lead

Computer Programmer

As a Computer Programmer, you will be responsible for writing and maintaining computer programs. This course may be useful for Computer Programmers who are responsible for working on software development projects that involve legacy code. You will learn techniques to test legacy code, which is often difficult to test due to its complexity and lack of documentation. This course will also teach you how to create test doubles, which are objects that simulate the behavior of other objects, allowing you to test code without disrupting the production environment.

See salaries and explore the career path for Computer Programmer

Computer Systems Analyst

As a Computer Systems Analyst, you will be responsible for analyzing and designing computer systems. This course may be useful for Computer Systems Analysts who are responsible for working on software development projects that involve legacy code. You will learn techniques to test legacy code, which is often difficult to test due to its complexity and lack of documentation. This course will also teach you how to create test doubles, which are objects that simulate the behavior of other objects, allowing you to test code without disrupting the production environment.

See salaries and explore the career path for Computer Systems Analyst

Software Test Automation Engineer

As a Software Test Automation Engineer, you will be responsible for automating software testing processes. This course may be useful for Software Test Automation Engineers who are responsible for working on software development projects that involve legacy code. You will learn techniques to test legacy code, which is often difficult to test due to its complexity and lack of documentation. This course will also teach you how to create test doubles, which are objects that simulate the behavior of other objects, allowing you to test code without disrupting the production environment.

See salaries and explore the career path for Software Test Automation Engineer

Business Analyst

As a Business Analyst, you will be responsible for understanding and analyzing business requirements and translating them into technical specifications. This course may be useful for Business Analysts who are responsible for working on software development projects that involve legacy code. You will learn techniques to test legacy code, which is often difficult to test due to its complexity and lack of documentation. This course will also teach you how to create test doubles, which are objects that simulate the behavior of other objects, allowing you to test code without disrupting the production environment.

See salaries and explore the career path for Business Analyst

Database Administrator

As a Database Administrator, you will be responsible for managing and maintaining databases. This course may be useful for Database Administrators who are responsible for working on software development projects that involve legacy code. You will learn techniques to test legacy code, which is often difficult to test due to its complexity and lack of documentation. This course will also teach you how to create test doubles, which are objects that simulate the behavior of other objects, allowing you to test code without disrupting the production environment.

See salaries and explore the career path for Database Administrator

Network Administrator

As a Network Administrator, you will be responsible for managing and maintaining computer networks. This course may be useful for Network Administrators who are responsible for working on software development projects that involve legacy code. You will learn techniques to test legacy code, which is often difficult to test due to its complexity and lack of documentation. This course will also teach you how to create test doubles, which are objects that simulate the behavior of other objects, allowing you to test code without disrupting the production environment.

See salaries and explore the career path for Network Administrator

Systems Analyst

As a Systems Analyst, you will be responsible for analyzing and designing complex systems. This course may be useful for Systems Analysts who are responsible for working on software development projects that involve legacy code. You will learn techniques to test legacy code, which is often difficult to test due to its complexity and lack of documentation. This course will also teach you how to create test doubles, which are objects that simulate the behavior of other objects, allowing you to test code without disrupting the production environment.

See salaries and explore the career path for Systems Analyst

Project Manager

As a Project Manager, you will be responsible for planning, organizing, and executing software development projects. This course may be useful for Project Managers who are responsible for managing software development projects that involve legacy code. You will learn techniques to test legacy code, which is often difficult to test due to its complexity and lack of documentation. This course will also teach you how to create test doubles, which are objects that simulate the behavior of other objects, allowing you to test code without disrupting the production environment.

See salaries and explore the career path for Project Manager

Software Quality Assurance Engineer

As a Software Quality Assurance Engineer, you will be responsible for ensuring the quality of software products. This course may be useful for Software Quality Assurance Engineers who are responsible for working on software development projects that involve legacy code. You will learn techniques to test legacy code, which is often difficult to test due to its complexity and lack of documentation. This course will also teach you how to create test doubles, which are objects that simulate the behavior of other objects, allowing you to test code without disrupting the production environment.

See salaries and explore the career path for Software Quality Assurance Engineer

DevOps Engineer

As a DevOps Engineer, you will be responsible for bridging the gap between software development and operations. This course may be useful for DevOps Engineers who are responsible for working on software development projects that involve legacy code. You will learn techniques to test legacy code, which is often difficult to test due to its complexity and lack of documentation. This course will also teach you how to create test doubles, which are objects that simulate the behavior of other objects, allowing you to test code without disrupting the production environment.

See salaries and explore the career path for DevOps Engineer

Reading list

We've selected 14 books that we think will supplement your learning. Use these to develop background knowledge, enrich your coursework, and gain a deeper understanding of the topics covered in Unit Testing Legacy Code in Java SE 8.

The Art of Unit Testing, Third Edition

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Offers a comprehensive guide to unit testing, covering best practices, design patterns, and various testing tools. It provides valuable insights into the principles and techniques of effective unit testing, making it a valuable resource for developers of all levels.

Unit Testing Legacy Code in Java SE 8

What's inside

Syllabus

Good to know

Save this course

Activities

Career center

Reading list

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