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Only remove MockUtil declarations whose uses are all migrated #1084

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cb245bc
MockUtilsToStatic: only remove declarations whose uses are all migrated
martinfrancois Aug 10, 2026
1cc8df2
Preserve declarator spacing when removing the first or last declarator
timtebeek Aug 11, 2026
4f0f93e
Trim commentary
timtebeek Aug 11, 2026
a3b586b
Parameterize MockUtil declarator tests
martinfrancois Aug 16, 2026
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184 changes: 168 additions & 16 deletions src/main/java/org/openrewrite/java/testing/mockito/MockUtilsToStatic.java
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Original file line number Diff line number Diff line change
Expand Up @@ -16,13 +16,23 @@
package org.openrewrite.java.testing.mockito;

import lombok.Getter;
import lombok.RequiredArgsConstructor;
import org.jspecify.annotations.Nullable;
import org.openrewrite.*;
import org.openrewrite.internal.ListUtils;
import org.openrewrite.java.ChangeMethodTargetToStatic;
import org.openrewrite.java.DeleteStatement;
import org.openrewrite.java.JavaIsoVisitor;
import org.openrewrite.java.JavaVisitor;
import org.openrewrite.java.MethodMatcher;
import org.openrewrite.java.search.UsesType;
import org.openrewrite.java.tree.Expression;
import org.openrewrite.java.tree.J;
import org.openrewrite.java.tree.JRightPadded;
import org.openrewrite.java.tree.JavaType;
import org.openrewrite.java.tree.Space;

import java.util.List;
import java.util.concurrent.atomic.AtomicBoolean;

/**
* In Mockito 1 you use a code snippet like:
Expand Down Expand Up @@ -50,8 +60,11 @@ public TreeVisitor<?, ExecutionContext> getVisitor() {
}

public static class MockUtilsToStaticVisitor extends JavaVisitor<ExecutionContext> {
private static final MethodMatcher METHOD_MATCHER = new MethodMatcher("org.mockito.internal.util.MockUtil <constructor>()");
private final ChangeMethodTargetToStatic changeMethodTargetToStatic = new ChangeMethodTargetToStatic("org.mockito.internal.util.MockUtil *(..)", "org.mockito.internal.util.MockUtil", null, null, false);
private static final String MOCK_UTIL = "org.mockito.internal.util.MockUtil";
private static final String MOCK_UTIL_METHODS = MOCK_UTIL + " *(..)";
private static final MethodMatcher METHOD_MATCHER = new MethodMatcher(MOCK_UTIL + " <constructor>()");
private static final MethodMatcher MIGRATED_METHOD_MATCHER = new MethodMatcher(MOCK_UTIL_METHODS);
private final ChangeMethodTargetToStatic changeMethodTargetToStatic = new ChangeMethodTargetToStatic(MOCK_UTIL_METHODS, MOCK_UTIL, null, null, false);

@Override
public J visitCompilationUnit(J.CompilationUnit compilationUnit, ExecutionContext ctx) {
Expand All @@ -60,21 +73,160 @@ public J visitCompilationUnit(J.CompilationUnit compilationUnit, ExecutionContex
}

@Override
public J visitNewClass(J.NewClass newClass, ExecutionContext ctx) {
if (METHOD_MATCHER.matches(newClass)) {
// Check to see if the new MockUtil() is being assigned to a variable or field, like
// MockUtil util = new MockUtil();
// If it is, then we'll get rid of it

Cursor parent = getCursor().dropParentUntil(J.class::isInstance);
if (parent.getValue() instanceof J.VariableDeclarations.NamedVariable) {
Object namedVar = parent.dropParentUntil(J.class::isInstance).getValue();
if (namedVar instanceof J.VariableDeclarations) {
doAfterVisit(new DeleteStatement<>((J.VariableDeclarations) namedVar));
}
public J visitVariableDeclarations(J.VariableDeclarations multiVariable, ExecutionContext ctx) {
J.VariableDeclarations vd = (J.VariableDeclarations) super.visitVariableDeclarations(multiVariable, ctx);
// Uses of a visible field from another source file are not analysed
J.CompilationUnit scope = getCursor().firstEnclosing(J.CompilationUnit.class);
if (scope == null) {
return vd;
}

List<JRightPadded<J.VariableDeclarations.NamedVariable>> original = vd.getPadding().getVariables();
List<JRightPadded<J.VariableDeclarations.NamedVariable>> variables =
ListUtils.map(original, v -> isObsoleteMockUtilInstance(v.getElement(), scope) ? null : v);
if (variables.size() == original.size()) {
return vd;
}
if (variables.isEmpty()) {
if (getCursor().getParentTreeCursor().getValue() instanceof J.Block) {
maybeRemoveImport(MOCK_UTIL);
//noinspection DataFlowIssue
return null;
}
return vd;
}
if (original.get(0) != variables.get(0)) {
// The next declarator now carries the separation from the type expression
variables = ListUtils.mapFirst(variables, v -> v.getElement().getPrefix().getComments().isEmpty() ?
v.withElement(v.getElement().withPrefix(Space.SINGLE_SPACE)) : v);
}
JRightPadded<J.VariableDeclarations.NamedVariable> last = original.get(original.size() - 1);
if (variables.get(variables.size() - 1) != last) {
// The previous declarator now carries the separation from the semicolon
variables = ListUtils.mapLast(variables, v -> v.withAfter(last.getAfter()));
}
return vd.getPadding().withVariables(variables);
}

private static boolean isObsoleteMockUtilInstance(J.VariableDeclarations.NamedVariable variable, J.CompilationUnit scope) {
if (!(variable.getInitializer() instanceof J.NewClass) || !METHOD_MATCHER.matches((J.NewClass) variable.getInitializer())) {
return false;
}
JavaType.Variable variableType = variable.getVariableType();
// Without symbol attribution the uses cannot be proven obsolete
return variableType != null &&
!new FindUnmigratedUses(variableType, variable.getSimpleName()).reduce(scope, new AtomicBoolean()).get();
}

@RequiredArgsConstructor
private static class FindUnmigratedUses extends JavaIsoVisitor<AtomicBoolean> {
private final JavaType.Variable variableType;
private final String name;

@Override
public @Nullable J visit(@Nullable Tree tree, AtomicBoolean found) {
return found.get() ? (J) tree : super.visit(tree, found);
}

@Override
public J.Package visitPackage(J.Package pkg, AtomicBoolean found) {
// Package and import name segments are not uses of the variable
return pkg;
}

@Override
public J.Import visitImport(J.Import anImport, AtomicBoolean found) {
return anImport;
}

@Override
public J.Identifier visitIdentifier(J.Identifier identifier, AtomicBoolean found) {
if (!name.equals(identifier.getSimpleName()) ||
identifier.getFieldType() != null && !variableType.equals(identifier.getFieldType())) {
return identifier;
}
Cursor parent = getCursor().getParentTreeCursor();
if (!isNeverVariableReference(identifier, parent) && !isMigratedUse(identifier, parent)) {
found.set(true);
}
return identifier;
}

/**
* @return whether the identifier declares a variable or names something in another namespace, so that
* it can never reference the variable under analysis.
*/
private static boolean isNeverVariableReference(J.Identifier identifier, Cursor parentCursor) {
if (identifier.getFieldType() == null &&
(identifier.getType() instanceof JavaType.Class || identifier.getType() instanceof JavaType.GenericTypeVariable)) {
return true;
}
Object parent = parentCursor.getValue();
if (parent instanceof J.VariableDeclarations.NamedVariable) {
return ((J.VariableDeclarations.NamedVariable) parent).getName() == identifier;
}
if (parent instanceof J.MethodInvocation) {
return ((J.MethodInvocation) parent).getName() == identifier;
}
if (parent instanceof J.MethodDeclaration) {
return ((J.MethodDeclaration) parent).getName() == identifier;
}
if (parent instanceof J.ClassDeclaration) {
return ((J.ClassDeclaration) parent).getName() == identifier;
}
if (parent instanceof J.MemberReference) {
return ((J.MemberReference) parent).getReference() == identifier;
}
if (parent instanceof J.Label) {
return ((J.Label) parent).getLabel() == identifier;
}
if (parent instanceof J.Break) {
return ((J.Break) parent).getLabel() == identifier;
}
if (parent instanceof J.Continue) {
return ((J.Continue) parent).getLabel() == identifier;
}
if (parent instanceof J.EnumValue) {
return ((J.EnumValue) parent).getName() == identifier;
}
if (parent instanceof J.TypeParameter) {
return ((J.TypeParameter) parent).getName() == identifier;
}
if (parent instanceof J.Assignment) {
// The left side of an annotation element assignment names the element, not a variable
return ((J.Assignment) parent).getVariable() == identifier &&
parentCursor.getParentTreeCursor().getValue() instanceof J.Annotation;
}
if (parent instanceof J.FieldAccess) {
// Package and type segments carry no field type, unlike an attributed variable
return identifier.getFieldType() == null;
}
return false;
}

/**
* @return whether the identifier is the receiver of a call {@link ChangeMethodTargetToStatic} makes
* static, bare or through a field access, in which case the rewrite drops it and the instance with it.
*/
private static boolean isMigratedUse(J.Identifier identifier, Cursor parent) {
Object parentValue = parent.getValue();
if (parentValue instanceof J.FieldAccess && ((J.FieldAccess) parentValue).getName() == identifier) {
return isMigratedReceiver((J.FieldAccess) parentValue, parent.getParentTreeCursor().getValue());
}
return isMigratedReceiver(identifier, parentValue);
}

private static boolean isMigratedReceiver(Expression receiver, Object parent) {
if (parent instanceof J.MethodInvocation) {
J.MethodInvocation method = (J.MethodInvocation) parent;
return method.getSelect() == receiver && MIGRATED_METHOD_MATCHER.matches(method);
}
if (parent instanceof J.MemberReference) {
J.MemberReference reference = (J.MemberReference) parent;
return reference.getContaining() == receiver && MIGRATED_METHOD_MATCHER.matches(reference);
}
return false;
}
return super.visitNewClass(newClass, ctx);
}
}
}
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