Introduce JUnit factory method BugChecker #319
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| package tech.picnic.errorprone.bugpatterns; | ||
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| import static com.google.common.collect.ImmutableList.toImmutableList; | ||
| import static com.google.errorprone.BugPattern.LinkType.CUSTOM; | ||
| import static com.google.errorprone.BugPattern.SeverityLevel.SUGGESTION; | ||
| import static com.google.errorprone.BugPattern.StandardTags.STYLE; | ||
| import static com.google.errorprone.matchers.ChildMultiMatcher.MatchType.AT_LEAST_ONE; | ||
| import static com.google.errorprone.matchers.Matchers.allOf; | ||
| import static com.google.errorprone.matchers.Matchers.annotations; | ||
| import static com.google.errorprone.matchers.Matchers.anyOf; | ||
| import static com.google.errorprone.matchers.Matchers.enclosingClass; | ||
| import static com.google.errorprone.matchers.Matchers.hasModifier; | ||
| import static com.google.errorprone.matchers.Matchers.isType; | ||
| import static com.google.errorprone.matchers.Matchers.not; | ||
| import static java.util.stream.Collectors.joining; | ||
| import static tech.picnic.errorprone.bugpatterns.util.ConflictDetection.findMethodRenameBlocker; | ||
| import static tech.picnic.errorprone.bugpatterns.util.Documentation.BUG_PATTERNS_BASE_URL; | ||
| import static tech.picnic.errorprone.bugpatterns.util.MoreJUnitMatchers.HAS_METHOD_SOURCE; | ||
| import static tech.picnic.errorprone.bugpatterns.util.MoreJUnitMatchers.TEST_METHOD; | ||
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| import com.google.auto.service.AutoService; | ||
| import com.google.common.collect.ImmutableList; | ||
| import com.google.common.collect.Iterables; | ||
| import com.google.common.collect.Streams; | ||
| import com.google.errorprone.BugPattern; | ||
| import com.google.errorprone.VisitorState; | ||
| import com.google.errorprone.bugpatterns.BugChecker; | ||
| import com.google.errorprone.bugpatterns.BugChecker.MethodTreeMatcher; | ||
| import com.google.errorprone.fixes.SuggestedFix; | ||
| import com.google.errorprone.fixes.SuggestedFixes; | ||
| import com.google.errorprone.matchers.Description; | ||
| import com.google.errorprone.matchers.Matcher; | ||
| import com.google.errorprone.util.ASTHelpers; | ||
| import com.sun.source.tree.AnnotationTree; | ||
| import com.sun.source.tree.MethodTree; | ||
| import com.sun.source.tree.StatementTree; | ||
| import com.sun.source.tree.Tree.Kind; | ||
| import com.sun.source.tree.VariableTree; | ||
| import com.sun.tools.javac.parser.Tokens.Comment; | ||
| import com.sun.tools.javac.parser.Tokens.TokenKind; | ||
| import java.util.List; | ||
| import java.util.Optional; | ||
| import java.util.stream.Stream; | ||
| import javax.lang.model.element.Modifier; | ||
| import javax.lang.model.element.Name; | ||
| import tech.picnic.errorprone.bugpatterns.util.MoreASTHelpers; | ||
| import tech.picnic.errorprone.bugpatterns.util.MoreJUnitMatchers; | ||
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| /** | ||
| * A {@link BugChecker} that flags non-canonical JUnit factory method declarations and usages. | ||
| * | ||
| * <p>At Picnic, we consider a JUnit factory method canonical if it: | ||
| * | ||
| * <ul> | ||
| * <li>has the same name as the test method it provides test cases for, but with a `TestCases` | ||
| * suffix, and | ||
| * <li>has a comment which connects the return statement to the names of the parameters in the | ||
| * corresponding test method. | ||
| * </ul> | ||
| */ | ||
| @AutoService(BugChecker.class) | ||
| @BugPattern( | ||
| summary = "JUnit factory method declaration can likely be improved", | ||
| link = BUG_PATTERNS_BASE_URL + "JUnitFactoryMethodDeclaration", | ||
| linkType = CUSTOM, | ||
| severity = SUGGESTION, | ||
| tags = STYLE) | ||
| public final class JUnitFactoryMethodDeclaration extends BugChecker implements MethodTreeMatcher { | ||
| private static final long serialVersionUID = 1L; | ||
| private static final Matcher<MethodTree> HAS_UNMODIFIABLE_SIGNATURE = | ||
| anyOf( | ||
| annotations(AT_LEAST_ONE, isType("java.lang.Override")), | ||
| allOf( | ||
| not(hasModifier(Modifier.FINAL)), | ||
| not(hasModifier(Modifier.PRIVATE)), | ||
| enclosingClass(hasModifier(Modifier.ABSTRACT)))); | ||
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| /** Instantiates a new {@link JUnitFactoryMethodDeclaration} instance. */ | ||
| public JUnitFactoryMethodDeclaration() {} | ||
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| @Override | ||
| public Description matchMethod(MethodTree tree, VisitorState state) { | ||
| if (!TEST_METHOD.matches(tree, state) || !HAS_METHOD_SOURCE.matches(tree, state)) { | ||
| return Description.NO_MATCH; | ||
| } | ||
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| AnnotationTree methodSourceAnnotation = | ||
| ASTHelpers.getAnnotationWithSimpleName( | ||
| tree.getModifiers().getAnnotations(), "MethodSource"); | ||
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| Optional<ImmutableList<MethodTree>> factoryMethods = | ||
| MoreJUnitMatchers.extractSingleFactoryMethodName(methodSourceAnnotation) | ||
| .map(name -> MoreASTHelpers.findMethods(name, state)); | ||
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| if (factoryMethods.isEmpty() || factoryMethods.orElseThrow().size() != 1) { | ||
| return Description.NO_MATCH; | ||
| } | ||
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| MethodTree factoryMethod = Iterables.getOnlyElement(factoryMethods.orElseThrow()); | ||
| ImmutableList<Description> descriptions = | ||
| ImmutableList.<Description>builder() | ||
| .addAll( | ||
| getFactoryMethodNameFixes( | ||
| tree.getName(), methodSourceAnnotation, factoryMethod, state)) | ||
| .addAll(getReturnStatementCommentFixes(tree, factoryMethod, state)) | ||
| .build(); | ||
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| descriptions.forEach(state::reportMatch); | ||
| return Description.NO_MATCH; | ||
| } | ||
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| private ImmutableList<Description> getFactoryMethodNameFixes( | ||
| Name methodName, | ||
| AnnotationTree methodSourceAnnotation, | ||
| MethodTree factoryMethod, | ||
| VisitorState state) { | ||
| String expectedFactoryMethodName = methodName + "TestCases"; | ||
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| if (HAS_UNMODIFIABLE_SIGNATURE.matches(factoryMethod, state) | ||
| || factoryMethod.getName().toString().equals(expectedFactoryMethodName)) { | ||
| return ImmutableList.of(); | ||
| } | ||
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| Optional<String> blocker = | ||
| findMethodRenameBlocker( | ||
| ASTHelpers.getSymbol(factoryMethod), expectedFactoryMethodName, state); | ||
| if (blocker.isPresent()) { | ||
| reportMethodRenameBlocker( | ||
| factoryMethod, blocker.orElseThrow(), expectedFactoryMethodName, state); | ||
| return ImmutableList.of(); | ||
| } | ||
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| return ImmutableList.of( | ||
| buildDescription(methodSourceAnnotation) | ||
| .setMessage( | ||
| String.format( | ||
| "The test cases should be supplied by a method named `%s`", | ||
| expectedFactoryMethodName)) | ||
| .addFix( | ||
| SuggestedFixes.updateAnnotationArgumentValues( | ||
| methodSourceAnnotation, | ||
| state, | ||
| "value", | ||
| ImmutableList.of("\"" + expectedFactoryMethodName + "\"")) | ||
| .build()) | ||
| .build(), | ||
| buildDescription(factoryMethod) | ||
| .setMessage( | ||
| String.format( | ||
| "The test cases should be supplied by a method named `%s`", | ||
| expectedFactoryMethodName)) | ||
| .addFix(SuggestedFixes.renameMethod(factoryMethod, expectedFactoryMethodName, state)) | ||
| .build()); | ||
| } | ||
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| private void reportMethodRenameBlocker( | ||
| MethodTree tree, String reason, String suggestedName, VisitorState state) { | ||
| state.reportMatch( | ||
| buildDescription(tree) | ||
| .setMessage( | ||
| String.format( | ||
| "The test cases should be supplied by a method named `%s` (but note that %s)", | ||
| suggestedName, reason)) | ||
| .build()); | ||
| } | ||
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| private ImmutableList<Description> getReturnStatementCommentFixes( | ||
| MethodTree testMethod, MethodTree factoryMethod, VisitorState state) { | ||
| String expectedComment = createCommentContainingParameters(testMethod); | ||
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| List<? extends StatementTree> statements = factoryMethod.getBody().getStatements(); | ||
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| Stream<? extends StatementTree> returnStatementsNeedingComment = | ||
| Streams.mapWithIndex(statements.stream(), IndexedStatement::new) | ||
|
There was a problem hiding this comment. Can you elaborate a bit on this part? Why do we need an |
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| .filter(indexedStatement -> indexedStatement.getStatement().getKind() == Kind.RETURN) | ||
| .filter( | ||
| indexedStatement -> | ||
| !hasExpectedComment( | ||
| factoryMethod, | ||
| expectedComment, | ||
| statements, | ||
| indexedStatement.getIndex(), | ||
| state)) | ||
| .map(IndexedStatement::getStatement); | ||
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| return returnStatementsNeedingComment | ||
| .map( | ||
| s -> | ||
| buildDescription(s) | ||
| .setMessage( | ||
| "The return statement should be prefixed by a comment giving the names of the test case parameters") | ||
| .addFix(SuggestedFix.prefixWith(s, expectedComment + "\n")) | ||
| .build()) | ||
| .collect(toImmutableList()); | ||
| } | ||
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| private static String createCommentContainingParameters(MethodTree testMethod) { | ||
| return testMethod.getParameters().stream() | ||
| .map(VariableTree::getName) | ||
| .map(Object::toString) | ||
| .collect(joining(", ", "/* { ", " } */")); | ||
| } | ||
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| private static boolean hasExpectedComment( | ||
| MethodTree factoryMethod, | ||
| String expectedComment, | ||
| List<? extends StatementTree> statements, | ||
| long statementIndex, | ||
| VisitorState state) { | ||
| int startPosition = | ||
| statementIndex > 0 | ||
| ? state.getEndPosition(statements.get((int) statementIndex - 1)) | ||
| : ASTHelpers.getStartPosition(factoryMethod); | ||
| int endPosition = state.getEndPosition(statements.get((int) statementIndex)); | ||
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| ImmutableList<Comment> comments = | ||
| extractReturnStatementComments(startPosition, endPosition, state); | ||
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| return comments.stream() | ||
| .map(Comment::getText) | ||
| .anyMatch(comment -> comment.equals(expectedComment)); | ||
| } | ||
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| private static ImmutableList<Comment> extractReturnStatementComments( | ||
| int startPosition, int endPosition, VisitorState state) { | ||
| return state.getOffsetTokens(startPosition, endPosition).stream() | ||
| .filter(t -> t.kind() == TokenKind.RETURN) | ||
| .flatMap(errorProneToken -> errorProneToken.comments().stream()) | ||
| .collect(toImmutableList()); | ||
| } | ||
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| private static final class IndexedStatement { | ||
| private final StatementTree statement; | ||
| private final long index; | ||
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| private IndexedStatement(StatementTree statement, long index) { | ||
| this.statement = statement; | ||
| this.index = index; | ||
| } | ||
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| public StatementTree getStatement() { | ||
| return statement; | ||
| } | ||
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| public long getIndex() { | ||
| return index; | ||
| } | ||
| } | ||
| } | ||
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Can there be more than one statement that needs a comment? Don't think so right? If so, it would require an extra test for sure (or I am missing something). Otherwise, we can improve the code a bit I think.