Skip to content

AssertThrowsMinimizer: handle varargs, allow casts from null #5617

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
copybara-service merged 1 commit into from
Mar 20, 2026
+139 −5
Merged

AssertThrowsMinimizer: handle varargs, allow casts from null #5617

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
38 changes: 33 additions & 5 deletions core/src/main/java/com/google/errorprone/bugpatterns/AssertThrowsMinimizer.java
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -30,6 +30,7 @@
import static com.google.errorprone.util.ASTHelpers.getThrownExceptions;
import static com.google.errorprone.util.ASTHelpers.getType;
import static com.google.errorprone.util.ASTHelpers.isCheckedExceptionType;
import static com.google.errorprone.util.ASTHelpers.isSubtype;
import static java.util.stream.Collectors.toCollection;

import com.google.common.base.CaseFormat;
Expand Down Expand Up @@ -60,8 +61,10 @@
import com.sun.source.tree.NewClassTree;
import com.sun.source.tree.StatementTree;
import com.sun.source.tree.Tree;
import com.sun.source.tree.TypeCastTree;
import com.sun.source.util.TreePath;
import com.sun.tools.javac.code.Symbol;
import com.sun.tools.javac.code.Symbol.VarSymbol;
import com.sun.tools.javac.code.Symbol.MethodSymbol;
import com.sun.tools.javac.code.Type;
import com.sun.tools.javac.code.Types;
import java.util.HashSet;
Expand Down Expand Up @@ -145,14 +148,19 @@ private Optional<AssertThrows> matchMethodInvocation(
return Optional.empty();
}
}
MethodSymbol sym = getSymbol(runnable);
ImmutableList<Hoist> toHoist =
Streams.concat(
Stream.ofNullable(getReceiver(runnable))
.map(r -> new Hoist(r, receiverVariableName(r))),
Streams.zip(
runnable.getArguments().stream(),
getSymbol(runnable).getParameters().stream(),
(ExpressionTree a, VarSymbol p) -> new Hoist(a, p.getSimpleName().toString())))
Streams.concat(
sym.getParameters().stream(),
// if there are varargs, there may be more arguments than parameters
Stream.generate(() -> sym.getParameters().getLast()))
.map(p -> p.getSimpleName().toString()),
(ExpressionTree a, String p) -> new Hoist(a, p)))
.filter(h -> needsHoisting(h.site(), exceptionType, state))
.collect(toImmutableList());
if (toHoist.isEmpty()) {
Expand Down Expand Up @@ -188,7 +196,9 @@ public Description matchMethod(MethodTree tree, VisitorState state) {
state);
}

VariableNamer variableNamer = new VariableNamer(state);
// update the tree path so VariableName considers the method parameters
VariableNamer variableNamer =
new VariableNamer(state.withPath(new TreePath(state.getPath(), toFix.getFirst().runnable)));
for (AssertThrows current : toFix) {
StringBuilder hoistedVariables = new StringBuilder();
for (Hoist hoist : current.toHoist) {
Expand All @@ -203,7 +213,7 @@ public Description matchMethod(MethodTree tree, VisitorState state) {
"%s %s = %s;\n",
useVarType ? "var" : SuggestedFixes.qualifyType(state, fix, type),
identifier,
state.getSourceForNode(hoist.site())));
state.getSourceForNode(initializer(state, hoist.site(), type))));
fix.replace(hoist.site(), identifier);
}
fix.prefixWith(current.parent(), hoistedVariables.toString());
Expand All @@ -215,6 +225,18 @@ public Description matchMethod(MethodTree tree, VisitorState state) {
return describeMatch(toFix.getFirst().parent(), fix.build());
}

private ExpressionTree initializer(VisitorState state, ExpressionTree site, Type type) {
if (useVarType) {
return site;
}
if (site instanceof TypeCastTree typeCastTree
&& isSubtype(getType(typeCastTree.getExpression()), type, state)) {
// avoid unnecessary casts in hoisted variables
return typeCastTree.getExpression();
}
return site;
}

private void addThrows(
MethodTree tree, Type exceptionType, SuggestedFix.Builder fix, VisitorState state) {
var types = state.getTypes();
Expand Down Expand Up @@ -278,6 +300,12 @@ private boolean needsHoisting(ExpressionTree tree, Type exceptionType, VisitorSt
.orElse(Stream.empty()))
.anyMatch(t -> needsHoisting(t, exceptionType, state));
case NewClassTree newClassTree -> newClassTreeNeedsHoisting(newClassTree);
case TypeCastTree typeCastTree ->
needsHoisting(typeCastTree.getExpression(), exceptionType, state)
|| !isSubtype(
getType(typeCastTree.getExpression()),
getType(typeCastTree.getType()),
state);
default -> true;
};
if (!needsHoisting) {
Expand Down
106 changes: 106 additions & 0 deletions core/src/test/java/com/google/errorprone/bugpatterns/AssertThrowsMinimizerTest.java
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -906,4 +906,110 @@ void f() {
""")
.doTest(TEXT_MATCH);
}

@Test
public void varArgs() {
compilationHelper
.addInputLines(
"Test.java",
"""
import java.util.ArrayList;
import java.util.List;
import java.util.function.Supplier;
import static org.junit.Assert.assertThrows;

abstract class Test {
void f() {
assertThrows(IllegalStateException.class, () -> doSomething(getString(), getString()));
}

abstract String getString();

abstract void doSomething(String... strings);
}
""")
.addOutputLines(
"Test.java",
"""
import java.util.ArrayList;
import java.util.List;
import java.util.function.Supplier;
import static org.junit.Assert.assertThrows;

abstract class Test {
void f() {
String strings = getString();
String strings2 = getString();
assertThrows(IllegalStateException.class, () -> doSomething(strings, strings2));
}

abstract String getString();

abstract void doSomething(String... strings);
}
""")
.doTest(TEXT_MATCH);
}

@Test
public void cast() {
compilationHelper
.addInputLines(
"Test.java",
"""
import java.util.ArrayList;
import java.util.List;
import java.util.function.Supplier;
import static org.junit.Assert.assertThrows;

abstract class Test {
void f(String s, Object o) {
assertThrows(IllegalStateException.class, () -> doSomething((String) getString()));
assertThrows(IllegalStateException.class, () -> doSomething((String) s));
assertThrows(IllegalStateException.class, () -> doSomething((String) o));
assertThrows(IllegalStateException.class, () -> doSomething((Object) s));
assertThrows(IllegalStateException.class, () -> doSomething((Object) o));
assertThrows(IllegalStateException.class, () -> doSomething((String) null));
}

abstract String getString();

abstract Object getObject();

abstract void doSomething(String s);

abstract void doSomething(Object o);
}
""")
.addOutputLines(
"Test.java",
"""
import java.util.ArrayList;
import java.util.List;
import java.util.function.Supplier;
import static org.junit.Assert.assertThrows;

abstract class Test {
void f(String s, Object o) {
String s2 = getString();
assertThrows(IllegalStateException.class, () -> doSomething(s2));
assertThrows(IllegalStateException.class, () -> doSomething((String) s));
String s3 = (String) o;
assertThrows(IllegalStateException.class, () -> doSomething(s3));
assertThrows(IllegalStateException.class, () -> doSomething((Object) s));
assertThrows(IllegalStateException.class, () -> doSomething((Object) o));
assertThrows(IllegalStateException.class, () -> doSomething((String) null));
}

abstract String getString();

abstract Object getObject();

abstract void doSomething(String s);

abstract void doSomething(Object o);
}
""")
.doTest(TEXT_MATCH);
}
}
Loading