Only hoist the last statement into the assertThrows() lambda.

PiperOrigin-RevId: 927391038

Author: kluever

core/src/main/java/com/google/errorprone/bugpatterns/AssertThrowsUtils.java

@@ -18,7 +18,6 @@
 
 import static com.google.common.collect.ImmutableList.toImmutableList;
 import static com.google.common.collect.Iterables.getLast;
-import static com.google.common.collect.Iterables.getOnlyElement;
 import static com.google.errorprone.fixes.SuggestedFixes.renameVariableUsages;
 import static com.google.errorprone.util.ASTHelpers.getStartPosition;
 import static java.util.stream.Collectors.joining;
@@ -112,6 +111,10 @@ public static Optional<Fix> tryFailToAssertThrows(
           resources.stream().map(state::getSourceForNode).collect(joining("\n", "try (", ") {\n")));
       fixSuffix = "\n}";
     }
+    // Hoist all but the last statement out of the lambda to narrow the exception scope.
+    for (StatementTree statement : throwingStatements.subList(0, throwingStatements.size() - 1)) {
+      fixPrefix.append(state.getSourceForNode(statement)).append("\n");
+    }
     if (!catchStatements.isEmpty()) {
       String name = catchTree.getParameter().getName().toString();
       String newName = namer.avoidShadowing(name);
@@ -133,30 +136,22 @@ public static Optional<Fix> tryFailToAssertThrows(
                 .map(t -> state.getSourceForNode(t) + ", ")
                 .orElse(""),
             state.getSourceForNode(catchTree.getParameter().getType())));
-    boolean useExpressionLambda =
-        throwingStatements.size() == 1
-            && getOnlyElement(throwingStatements) instanceof ExpressionStatementTree;
+    StatementTree lastStatement = getLast(throwingStatements);
+    boolean useExpressionLambda = lastStatement instanceof ExpressionStatementTree;
     if (!useExpressionLambda) {
       fixPrefix.append("{");
     }
-    fix.replace(
-        getStartPosition(tryTree),
-        getStartPosition(throwingStatements.iterator().next()),
-        fixPrefix.toString());
+    fix.replace(getStartPosition(tryTree), getStartPosition(lastStatement), fixPrefix.toString());
     if (useExpressionLambda) {
-      fix.postfixWith(
-          ((ExpressionStatementTree) throwingStatements.iterator().next()).getExpression(), ")");
+      fix.postfixWith(((ExpressionStatementTree) lastStatement).getExpression(), ")");
     } else {
-      fix.postfixWith(getLast(throwingStatements), "});");
+      fix.postfixWith(lastStatement, "});");
     }
     if (catchStatements.isEmpty()) {
-      fix.replace(
-          state.getEndPosition(getLast(throwingStatements)),
-          state.getEndPosition(tryTree),
-          fixSuffix);
+      fix.replace(state.getEndPosition(lastStatement), state.getEndPosition(tryTree), fixSuffix);
     } else {
       fix.replace(
-          /* startPos= */ state.getEndPosition(getLast(throwingStatements)),
+          /* startPos= */ state.getEndPosition(lastStatement),
           /* endPos= */ getStartPosition(catchStatements.getFirst()),
           "\n");
       fix.replace(

core/src/test/java/com/google/errorprone/bugpatterns/MissingFailTest.java

@@ -948,13 +948,8 @@ class ExceptionTest {
               @Test
               public void f() throws Exception {
                 Path p = Paths.get("NOSUCH");
-                IOException e =
-                    assertThrows(
-                        IOException.class,
-                        () -> {
-                          Files.readAllBytes(p);
-                          Files.readAllBytes(p);
-                        });
+                Files.readAllBytes(p);
+                IOException e = assertThrows(IOException.class, () -> Files.readAllBytes(p));
                 assertThat(e).hasMessageThat().contains("NOSUCH");
               }
 

core/src/test/java/com/google/errorprone/bugpatterns/TryFailRefactoringTest.java

@@ -45,12 +45,12 @@ public void catchBlock() {
 
             class ExceptionTest {
               @Test
-              public void f(String message) throws Exception {
+              public void f(String msg) throws Exception {
                 Path p = Paths.get("NOSUCH");
                 try {
                   Files.readAllBytes(p);
                   Files.readAllBytes(p);
-                  fail(message);
+                  fail(msg);
                 } catch (IOException e) {
                   assertThat(e).hasMessageThat().contains("NOSUCH");
                 }
@@ -81,16 +81,10 @@ public void g() throws Exception {
 
             class ExceptionTest {
               @Test
-              public void f(String message) throws Exception {
+              public void f(String msg) throws Exception {
                 Path p = Paths.get("NOSUCH");
-                IOException e =
-                    assertThrows(
-                        message,
-                        IOException.class,
-                        () -> {
-                          Files.readAllBytes(p);
-                          Files.readAllBytes(p);
-                        });
+                Files.readAllBytes(p);
+                IOException e = assertThrows(msg, IOException.class, () -> Files.readAllBytes(p));
                 assertThat(e).hasMessageThat().contains("NOSUCH");
               }
 
@@ -169,11 +163,11 @@ public void tryWithResources() {
 
             class ExceptionTest {
               @Test
-              public void f(String message, CharSource cs) throws IOException {
+              public void f(String msg, CharSource cs) throws IOException {
                 try (BufferedReader buf = cs.openBufferedStream();
                     PushbackReader pbr = new PushbackReader(buf)) {
                   pbr.read();
-                  fail(message);
+                  fail(msg);
                 } catch (IOException e) {
                   assertThat(e).hasMessageThat().contains("NOSUCH");
                 }
@@ -195,10 +189,10 @@ public void f(String message, CharSource cs) throws IOException {
 
             class ExceptionTest {
               @Test
-              public void f(String message, CharSource cs) throws IOException {
+              public void f(String msg, CharSource cs) throws IOException {
                 try (BufferedReader buf = cs.openBufferedStream();
                     PushbackReader pbr = new PushbackReader(buf)) {
-                  IOException e = assertThrows(message, IOException.class, () -> pbr.read());
+                  IOException e = assertThrows(msg, IOException.class, () -> pbr.read());
                   assertThat(e).hasMessageThat().contains("NOSUCH");
                 }
               }