Use Plain JUnit5 for advanced test assertions
Proposed | 14 June 2023 | Lawrence Goldstien
Context and Problem Statement
How to write readable test assertions? How to write readable test assertions for advanced tests?
Considered Options
- Plain JUnit5
- Hamcrest
- AssertJ
Decision Outcome
Chosen option: "Plain JUnit5", because comes out best (see below).
Consequences
- Good, because tests are more readable
- Good, because more easy to write tests
- Good, because more readable assertions
- Bad, because more complicated testing leads to more complicated assertions
Pros and Cons of the Options
Plain JUnit5
Homepage: https://junit.org/junit5/docs/current/user-guide/ JabRef testing guidelines: https://devdocs.jabref.org/getting-into-the-code/code-howtos#test-cases
Example:
String actual = markdownFormatter.format(source);
assertTrue(actual.contains("Markup<br />"));
assertTrue(actual.contains("<li>list item one</li>"));
assertTrue(actual.contains("<li>list item 2</li>"));
assertTrue(actual.contains("> rest"));
assertFalse(actual.contains("\n"));
- Good, because Junit5 is "common Java knowledge"
- Bad, because complex assertions tend to get hard to read
- Bad, because no fluent API
Hamcrest
Homepage: https://github.com/hamcrest/JavaHamcrest
- Good, because offers advanced matchers (such as
contains) - Bad, because not full fluent API
- Bad, because entry barrier is increased
AssertJ
Homepage: https://joel-costigliola.github.io/assertj/
Example:
assertThat(markdownFormatter.format(source))
.contains("Markup<br />")
.contains("<li>list item one</li>")
.contains("<li>list item 2</li>")
.contains("> rest")
.doesNotContain("\n");
- Good, because offers fluent assertions
- Good, because allows partial string testing to focus on important parts
- Good, because assertions are more readable
- Bad, because not commonly used
- Bad, because newcomers have to learn an additional language to express test cases
- Bad, because entry barrier is increased
- Bad, because expressions of test cases vary from unit test to unit test
More Information
German comparison between Hamcrest and AssertJ: https://www.sigs-datacom.de/uploads/tx_dmjournals/philipp_JS_06_15_gRfN.pdf.
Work in Progress!
This site is a work in progress and any opinions contained here are intended to spark discussion within each discipline's community of practice.
Created: 2023-06-23