New update with slides #233
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WalkthroughThe changes introduce a new Roman numeral converter utility class and its comprehensive unit tests within the Maven demo example. Additionally, the documentation presentation is significantly expanded, featuring new sections, slides, and a restructured agenda to provide detailed explanations about system prompts and related concepts. Changes
Sequence Diagram(s)sequenceDiagram
participant Tester
participant RomanNumeralConverter
Tester->>RomanNumeralConverter: toRoman(int number)
alt number is null (Integer)
RomanNumeralConverter-->>Tester: return ""
else number < 1 or > 3999
RomanNumeralConverter-->>Tester: throw IllegalArgumentException
else valid number
RomanNumeralConverter->>RomanNumeralConverter: Convert to Roman numeral string
RomanNumeralConverter-->>Tester: return Roman numeral string
end
Estimated code review effort🎯 3 (Moderate) | ⏱️ ~18 minutes Poem
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Actionable comments posted: 3
🧹 Nitpick comments (1)
examples/maven-demo/src/main/java/info/jab/demo/RomanNumeralConverter.java (1)
61-66: Consider Optional for clearer null handling.The current implementation correctly handles null input. However, consider returning
Optional<String>instead of an empty string to make the absence of a value more explicit to callers.Alternative implementation:
- public String toRoman(Integer number) { - if (Objects.isNull(number)) { - return ""; - } - return toRoman(number.intValue()); + public Optional<String> toRoman(Integer number) { + if (Objects.isNull(number)) { + return Optional.empty(); + } + return Optional.of(toRoman(number.intValue()));
📜 Review details
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⛔ Files ignored due to path filters (5)
docs/dvbe25/images/bg.jpgis excluded by!**/*.jpgdocs/dvbe25/images/bg2.jpgis excluded by!**/*.jpgdocs/dvbe25/images/demo.pngis excluded by!**/*.pngdocs/dvbe25/images/jabAvatar.jpgis excluded by!**/*.jpgdocs/dvbe25/images/ppt.pngis excluded by!**/*.png
📒 Files selected for processing (3)
docs/dvbe25/index.html(2 hunks)examples/maven-demo/src/main/java/info/jab/demo/RomanNumeralConverter.java(1 hunks)examples/maven-demo/src/test/java/info/jab/demo/RomanNumeralConverterTest.java(1 hunks)
🧰 Additional context used
📓 Path-based instructions (3)
**/*.java
📄 CodeRabbit Inference Engine (.cursor/rules/121-java-object-oriented-design.mdc)
**/*.java: Classes should use the most restrictive access level that makes sense (minimize accessibility of classes and members).
In public classes, use accessor methods (getters/setters), not public fields.
Make classes immutable when possible.
Design and document for inheritance or else prohibit it (make classes final if not designed for inheritance).
Use enums instead of int constants for type safety.
Don't derive values from enum ordinals; use instance fields instead.
Replace bit field enums with EnumSet for better type safety and performance.
Use EnumMap for enum-keyed data instead of ordinal indexing.
Always use @OverRide when overriding methods.
Validate method parameters early and clearly.
Make defensive copies when accepting or returning mutable objects.
Never return null from methods that return collections or arrays; return empty collections or arrays instead.
Use Optional for methods that may not return a value, but use it judiciously (not for fields, parameters, or collections).
Don't use exceptions for ordinary control flow; use them only for exceptional conditions.
Use checked exceptions for recoverable conditions and runtime exceptions for programming errors.
Use standard Java exceptions when appropriate, rather than creating unnecessary custom exceptions.
Provide detailed, actionable information in exception messages.
Always handle exceptions appropriately; never ignore them silently.
Use static factory methods instead of constructors when more flexibility is needed.
Use the Builder pattern for classes with multiple optional parameters.
Enforce the Singleton property with a private constructor or an enum type.
Prefer dependency injection to hardwiring resources.
Reuse objects when possible to improve performance and avoid creating unnecessary objects.
Design methods for clarity, safety, and usability; choose method names carefully and avoid long parameter lists.
**/*.java: Adhere to standard Java naming conventions for all code elements (packag...
Files:
examples/maven-demo/src/main/java/info/jab/demo/RomanNumeralConverter.javaexamples/maven-demo/src/test/java/info/jab/demo/RomanNumeralConverterTest.java
**/test/**/*.java
📄 CodeRabbit Inference Engine (.cursor/rules/125-java-concurrency.mdc)
Rigorously test concurrent Java code using unit tests, stress tests, integration tests, thread dump analysis, and concurrency testing tools. Use JUnit 5 with parallel execution capabilities.
Files:
examples/maven-demo/src/test/java/info/jab/demo/RomanNumeralConverterTest.java
**/*Test.java
📄 CodeRabbit Inference Engine (.cursor/rules/126-java-logging.mdc)
Integrate logging validation into the testing strategy: assert that critical log messages are generated as expected, verify log formats, test log level filtering, and assess logging performance impact.
Files:
examples/maven-demo/src/test/java/info/jab/demo/RomanNumeralConverterTest.java
🧠 Learnings (13)
📚 Learning: applies to cursor-rules-java.md : create a markdown file named `cursor-rules-java.md` in the project...
Learnt from: CR
PR: jabrena/cursor-rules-java#0
File: .cursor/rules/100-java-cursor-rules-list.mdc:0-0
Timestamp: 2025-07-24T11:24:47.720Z
Learning: Applies to CURSOR-RULES-JAVA.md : Create a markdown file named `CURSOR-RULES-JAVA.md` in the project root directory with the exact content and structure as defined in the embedded template, listing all specified Cursor Rules for Java development.
Applied to files:
docs/dvbe25/index.html
📚 Learning: only use cursor rules that appear in the embedded template when generating `cursor-rules-java.md`....
Learnt from: CR
PR: jabrena/cursor-rules-java#0
File: .cursor/rules/100-java-cursor-rules-list.mdc:0-0
Timestamp: 2025-07-24T11:24:47.720Z
Learning: Only use cursor rules that appear in the embedded template when generating `CURSOR-RULES-JAVA.md`.
Applied to files:
docs/dvbe25/index.html
📚 Learning: do not add, remove, or modify any steps, sections, or cursor rules that are not explicitly shown in ...
Learnt from: CR
PR: jabrena/cursor-rules-java#0
File: .cursor/rules/100-java-cursor-rules-list.mdc:0-0
Timestamp: 2025-07-24T11:24:47.720Z
Learning: Do not add, remove, or modify any steps, sections, or cursor rules that are not explicitly shown in the embedded template when generating `CURSOR-RULES-JAVA.md`.
Applied to files:
docs/dvbe25/index.html
📚 Learning: applies to src/test/java/**/*@(test|tests|testcase).java : test exception scenarios effectively: use...
Learnt from: CR
PR: jabrena/cursor-rules-java#0
File: .cursor/rules/131-java-unit-testing.mdc:0-0
Timestamp: 2025-07-24T11:29:11.227Z
Learning: Applies to src/test/java/**/*@(Test|Tests|TestCase).java : Test exception scenarios effectively: use AssertJ's assertThatThrownBy to verify expected exceptions and their messages, and test graceful degradation when dependencies are unavailable.
Applied to files:
examples/maven-demo/src/test/java/info/jab/demo/RomanNumeralConverterTest.java
📚 Learning: applies to src/test/java/**/*@(test|tests|testcase).java : organize test code effectively: keep test...
Learnt from: CR
PR: jabrena/cursor-rules-java#0
File: .cursor/rules/131-java-unit-testing.mdc:0-0
Timestamp: 2025-07-24T11:29:11.227Z
Learning: Applies to src/test/java/**/*@(Test|Tests|TestCase).java : Organize test code effectively: keep test methods small and focused, use helper methods to avoid code duplication, and utilize parameterized tests for input variations.
Applied to files:
examples/maven-demo/src/test/java/info/jab/demo/RomanNumeralConverterTest.java
📚 Learning: applies to src/test/java/**/*@(test|tests|testcase).java : avoid common testing anti-patterns: do no...
Learnt from: CR
PR: jabrena/cursor-rules-java#0
File: .cursor/rules/131-java-unit-testing.mdc:0-0
Timestamp: 2025-07-24T11:29:11.227Z
Learning: Applies to src/test/java/**/*@(Test|Tests|TestCase).java : Avoid common testing anti-patterns: do not test implementation details, avoid hard-coded values, keep test logic simple, do not ignore edge cases, avoid slow tests, do not over-rely on mocks, and never ignore failing tests.
Applied to files:
examples/maven-demo/src/test/java/info/jab/demo/RomanNumeralConverterTest.java
📚 Learning: applies to src/test/java/**/*@(test|tests|testcase).java : ensure each test has its own isolated sta...
Learnt from: CR
PR: jabrena/cursor-rules-java#0
File: .cursor/rules/131-java-unit-testing.mdc:0-0
Timestamp: 2025-07-24T11:29:11.227Z
Learning: Applies to src/test/java/**/*@(Test|Tests|TestCase).java : Ensure each test has its own isolated state to avoid interference between tests; use BeforeEach to reset state and prefer immutable objects.
Applied to files:
examples/maven-demo/src/test/java/info/jab/demo/RomanNumeralConverterTest.java
📚 Learning: verify that any new testing dependencies (assertj, mockito extensions) are properly configured and c...
Learnt from: CR
PR: jabrena/cursor-rules-java#0
File: .cursor/rules/131-java-unit-testing.mdc:0-0
Timestamp: 2025-07-24T11:29:11.227Z
Learning: Verify that any new testing dependencies (AssertJ, Mockito extensions) are properly configured and compatible.
Applied to files:
examples/maven-demo/src/test/java/info/jab/demo/RomanNumeralConverterTest.java
📚 Learning: applies to src/test/java/**/*@(test|tests|testcase).java : use @parameterizedtest for testing the sa...
Learnt from: CR
PR: jabrena/cursor-rules-java#0
File: .cursor/rules/131-java-unit-testing.mdc:0-0
Timestamp: 2025-07-24T11:29:11.227Z
Learning: Applies to src/test/java/**/*@(Test|Tests|TestCase).java : Use ParameterizedTest for testing the same logic with different inputs; leverage JUnit 5's parameterized tests to avoid code duplication.
Applied to files:
examples/maven-demo/src/test/java/info/jab/demo/RomanNumeralConverterTest.java
📚 Learning: applies to src/test/java/**/*@(test|tests|testcase).java : prefer assertj for assertions; employ ass...
Learnt from: CR
PR: jabrena/cursor-rules-java#0
File: .cursor/rules/131-java-unit-testing.mdc:0-0
Timestamp: 2025-07-24T11:29:11.227Z
Learning: Applies to src/test/java/**/*@(Test|Tests|TestCase).java : Prefer AssertJ for assertions; employ AssertJ's fluent API (org.assertj.core.api.Assertions.assertThat) for more readable, expressive, and maintainable assertions compared to JUnit Jupiter's Assertions class or Hamcrest matchers.
Applied to files:
examples/maven-demo/src/test/java/info/jab/demo/RomanNumeralConverterTest.java
📚 Learning: applies to src/test/java/**/*@(test|tests|testcase).java : write descriptive test method names or us...
Learnt from: CR
PR: jabrena/cursor-rules-java#0
File: .cursor/rules/131-java-unit-testing.mdc:0-0
Timestamp: 2025-07-24T11:29:11.227Z
Learning: Applies to src/test/java/**/*@(Test|Tests|TestCase).java : Write descriptive test method names or use DisplayName; test names should clearly communicate the scenario being tested and the expected outcome.
Applied to files:
examples/maven-demo/src/test/java/info/jab/demo/RomanNumeralConverterTest.java
📚 Learning: applies to src/test/java/**/*@(test|tests|testcase).java : test classes and methods should have pack...
Learnt from: CR
PR: jabrena/cursor-rules-java#0
File: .cursor/rules/131-java-unit-testing.mdc:0-0
Timestamp: 2025-07-24T11:29:11.227Z
Learning: Applies to src/test/java/**/*@(Test|Tests|TestCase).java : Test classes and methods should have package-private visibility; there is no need for them to be public.
Applied to files:
examples/maven-demo/src/test/java/info/jab/demo/RomanNumeralConverterTest.java
📚 Learning: applies to **/test/**/*.java : rigorously test concurrent java code using unit tests, stress tests, ...
Learnt from: CR
PR: jabrena/cursor-rules-java#0
File: .cursor/rules/125-java-concurrency.mdc:0-0
Timestamp: 2025-07-24T11:27:59.108Z
Learning: Applies to **/test/**/*.java : Rigorously test concurrent Java code using unit tests, stress tests, integration tests, thread dump analysis, and concurrency testing tools. Use JUnit 5 with parallel execution capabilities.
Applied to files:
examples/maven-demo/src/test/java/info/jab/demo/RomanNumeralConverterTest.java
🔇 Additional comments (7)
examples/maven-demo/src/main/java/info/jab/demo/RomanNumeralConverter.java (2)
18-24: LGTM! Well-designed constant arrays.The parallel arrays are properly declared as private static final and contain the correct Roman numeral mappings in descending order, which is essential for the greedy conversion algorithm to work correctly.
33-51: LGTM! Solid implementation with proper validation.The method correctly validates input parameters early, uses an efficient greedy algorithm, and handles string building efficiently with StringBuilder. The exception message is clear and actionable.
examples/maven-demo/src/test/java/info/jab/demo/RomanNumeralConverterTest.java (4)
21-69: LGTM! Comprehensive and well-organized test coverage.The test methods are properly structured with descriptive
@DisplayNameannotations, focused on specific ranges, and provide comprehensive coverage of basic Roman numeral conversions. The organization by categories (single digits, tens, hundreds, thousands) makes the tests easy to understand and maintain.
71-92: LGTM! Excellent use of parameterized testing.The parameterized test effectively covers various complex conversion scenarios while avoiding code duplication. The test cases include edge cases and complex numbers, providing good coverage with a clean, maintainable approach.
112-134: Good coverage of Integer wrapper scenarios.The tests comprehensively cover the Integer wrapper method including null handling and invalid values. The same AssertJ recommendation applies to the exception testing here for consistency.
136-143: LGTM! Critical edge case testing.These complex subtractive notation tests are essential for validating the algorithm's correctness in the most challenging scenarios. The test cases are well-chosen and cover combinations of subtractive patterns that could easily break with incorrect implementations.
docs/dvbe25/index.html (1)
38-204: LGTM! Well-structured presentation with comprehensive content.The HTML structure is valid and follows reveal.js conventions correctly. The presentation has been significantly enhanced with:
- Proper section organization
- Educational content about system prompts
- Clear agenda structure
- Relevant references and links
The technical implementation is sound and the content appears well-organized for educational purposes.
| * - I = 1, V = 5, X = 10, L = 50, C = 100, D = 500, M = 1000 | ||
| * - Subtractive notation: IV = 4, IX = 9, XL = 40, XC = 90, CD = 400, CM = 900 | ||
| */ | ||
| public class RomanNumeralConverter { |
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🛠️ Refactor suggestion
Make utility class final and methods static.
This class appears to be a utility class that's not designed for inheritance. According to coding guidelines, it should be made final to prevent inheritance and methods should be static since they don't require instance state.
Apply this diff to improve the class design:
-public class RomanNumeralConverter {
+public final class RomanNumeralConverter {And make methods static:
- public String toRoman(int number) {
+ public static String toRoman(int number) {- public String toRoman(Integer number) {
+ public static String toRoman(Integer number) {🤖 Prompt for AI Agents
In examples/maven-demo/src/main/java/info/jab/demo/RomanNumeralConverter.java at
line 15, the RomanNumeralConverter class should be declared final to prevent
inheritance, and all its methods should be made static since they do not depend
on instance state. Modify the class declaration to include the final keyword and
update each method by adding the static modifier.
| import static org.junit.jupiter.api.Assertions.*; | ||
|
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| class RomanNumeralConverterTest { | ||
|
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| private RomanNumeralConverter converter; | ||
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| @BeforeEach | ||
| void setUp() { | ||
| converter = new RomanNumeralConverter(); | ||
| } |
There was a problem hiding this comment.
🛠️ Refactor suggestion
Use AssertJ for more expressive assertions.
According to coding guidelines, prefer AssertJ's fluent API over JUnit assertions for better readability and expressiveness. Also, if the RomanNumeralConverter methods become static as suggested, the @BeforeEach setup would be unnecessary.
Apply this diff to use AssertJ:
-import static org.junit.jupiter.api.Assertions.*;
+import static org.assertj.core.api.Assertions.*;If methods become static, the setup can be simplified:
- private RomanNumeralConverter converter;
-
- @BeforeEach
- void setUp() {
- converter = new RomanNumeralConverter();
- }Committable suggestion skipped: line range outside the PR's diff.
🤖 Prompt for AI Agents
In
examples/maven-demo/src/test/java/info/jab/demo/RomanNumeralConverterTest.java
around lines 10 to 19, replace JUnit assertions with AssertJ assertions for more
expressive and readable tests. Also, if RomanNumeralConverter methods are
changed to static, remove the @BeforeEach setup method and the converter
instance variable, calling static methods directly in tests instead.
| @ParameterizedTest | ||
| @DisplayName("Should throw exception for invalid numbers") | ||
| @ValueSource(ints = {0, -1, -10, 4000, 5000, 10000}) | ||
| void testInvalidNumbers(int invalidNumber) { | ||
| IllegalArgumentException exception = assertThrows( | ||
| IllegalArgumentException.class, | ||
| () -> converter.toRoman(invalidNumber) | ||
| ); | ||
| assertTrue(exception.getMessage().contains("Number must be between 1 and 3999")); | ||
| } |
There was a problem hiding this comment.
🛠️ Refactor suggestion
Use AssertJ for exception testing.
The exception testing logic is correct, but should use AssertJ's assertThatThrownBy for consistency and better expressiveness according to coding guidelines.
Apply this diff:
- IllegalArgumentException exception = assertThrows(
- IllegalArgumentException.class,
- () -> converter.toRoman(invalidNumber)
- );
- assertTrue(exception.getMessage().contains("Number must be between 1 and 3999"));
+ assertThatThrownBy(() -> converter.toRoman(invalidNumber))
+ .isInstanceOf(IllegalArgumentException.class)
+ .hasMessageContaining("Number must be between 1 and 3999");🤖 Prompt for AI Agents
In
examples/maven-demo/src/test/java/info/jab/demo/RomanNumeralConverterTest.java
around lines 101 to 110, replace the JUnit assertThrows and assertTrue calls
with AssertJ's assertThatThrownBy method to test for exceptions. Use
assertThatThrownBy with a lambda invoking converter.toRoman(invalidNumber), then
chain isInstanceOf(IllegalArgumentException.class) and
hasMessageContaining("Number must be between 1 and 3999") for clearer and more
consistent exception assertions.
1 participant
Summary by CodeRabbit
New Features
Bug Fixes
Tests