Add a check to reformat poorly formatted EP tests.

core/pom.xml

@@ -68,6 +68,12 @@
       <version>${project.version}</version>
       <scope>test</scope>
     </dependency>
+    <dependency>
+      <!-- Apache 2.0 -->
+      <groupId>com.google.googlejavaformat</groupId>
+      <artifactId>google-java-format</artifactId>
+      <version>1.19.1</version>
+    </dependency>
     <dependency>
       <!-- MIT -->
       <groupId>org.pcollections</groupId>

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

@@ -0,0 +1,132 @@
+/*
+ * Copyright 2024 The Error Prone Authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.errorprone.bugpatterns;
+
+import static com.google.errorprone.BugPattern.SeverityLevel.WARNING;
+import static com.google.errorprone.matchers.Description.NO_MATCH;
+import static com.google.errorprone.matchers.Matchers.anyOf;
+import static com.google.errorprone.matchers.method.MethodMatchers.instanceMethod;
+import static com.google.errorprone.util.ASTHelpers.getStartPosition;
+import static com.google.errorprone.util.ErrorProneTokens.getTokens;
+import static com.google.errorprone.util.SourceVersion.supportsTextBlocks;
+import static java.util.stream.Collectors.joining;
+
+import com.google.common.base.Splitter;
+import com.google.common.escape.Escaper;
+import com.google.common.escape.Escapers;
+import com.google.errorprone.BugPattern;
+import com.google.errorprone.VisitorState;
+import com.google.errorprone.bugpatterns.BugChecker.MethodInvocationTreeMatcher;
+import com.google.errorprone.fixes.SuggestedFix;
+import com.google.errorprone.matchers.Description;
+import com.google.errorprone.matchers.Matcher;
+import com.google.googlejavaformat.java.Formatter;
+import com.google.googlejavaformat.java.FormatterException;
+import com.sun.source.tree.ExpressionTree;
+import com.sun.source.tree.LiteralTree;
+import com.sun.source.tree.MethodInvocationTree;
+import com.sun.tools.javac.parser.Tokens.TokenKind;
+
+/** See the summary. */
+@BugPattern(
+    severity = WARNING,
+    summary = "This test data will be more readable if correctly formatted.")
+public final class MisformattedTestData extends BugChecker implements MethodInvocationTreeMatcher {
+  @Override
+  public Description matchMethodInvocation(MethodInvocationTree tree, VisitorState state) {
+    // We're not only matching text blocks below, just taking the fact that it's a single literal
+    // argument containing source code as a sign that it should be formatted in a text block.
+    if (!supportsTextBlocks(state.context)) {
+      return NO_MATCH;
+    }
+    if (!ADD_SOURCE_CALL.matches(tree, state)) {
+      return NO_MATCH;
+    }
+    if (tree.getArguments().size() != 2) {
+      return NO_MATCH;
+    }
+    var sourceTree = tree.getArguments().get(1);
+    if (!(sourceTree instanceof LiteralTree)) {
+      return NO_MATCH;
+    }
+    var sourceValue = ((LiteralTree) sourceTree).getValue();
+    if (!(sourceValue instanceof String)) {
+      return NO_MATCH;
+    }
+
+    Formatter formatter = new Formatter();
+    String formattedSource;
+    try {
+      formattedSource = formatter.formatSource((String) sourceValue);
+    } catch (FormatterException exception) {
+      return NO_MATCH;
+    }
+    if (formattedSource.equals(sourceValue)) {
+      return NO_MATCH;
+    }
+    // This is a bit crude: but tokenize between the comma and the 2nd argument in order to work out
+    // an appropriate indent level for the text block. This is assuming that the source has already
+    // been formatted so that the arguments are nicely indented.
+    int startPos = state.getEndPosition(tree.getArguments().get(0));
+    int endPos = getStartPosition(tree.getArguments().get(1));
+    var tokens =
+        getTokens(
+            state.getSourceCode().subSequence(startPos, endPos).toString(),
+            startPos,
+            state.context);
+    var afterCommaPos =
+        tokens.reverse().stream()
+            .filter(t -> t.kind().equals(TokenKind.COMMA))
+            .findFirst()
+            .orElseThrow()
+            .endPos();
+    var spaces =
+        state.getSourceCode().subSequence(afterCommaPos, endPos).toString().replace("\n", "");
+    return describeMatch(
+        sourceTree,
+        SuggestedFix.replace(
+            sourceTree,
+            "\"\"\"\n"
+                + LINE_SPLITTER
+                    .splitToStream(escape(formattedSource))
+                    .map(line -> line.isEmpty() ? "" : spaces + line)
+                    .collect(joining("\n"))
+                + spaces
+                + "\"\"\""));
+  }
+
+  // TODO(ghm): Consider generalising this via an annotation.
+  private static final Matcher<ExpressionTree> ADD_SOURCE_CALL =
+      anyOf(
+          instanceMethod()
+              .onExactClass("com.google.errorprone.CompilationTestHelper")
+              .named("addSourceLines"),
+          instanceMethod()
+              .onExactClass("com.google.errorprone.BugCheckerRefactoringTestHelper")
+              .named("addInputLines"),
+          instanceMethod()
+              .onExactClass("com.google.errorprone.BugCheckerRefactoringTestHelper")
+              .named("addOutputLines"));
+
+  private static final Splitter LINE_SPLITTER = Splitter.on('\n');
+
+  private static String escape(String line) {
+    return ESCAPER.escape(line).replace("\"\"\"", "\\\"\"\"");
+  }
+
+  private static final Escaper ESCAPER = Escapers.builder().addEscape('\\', "\\\\").build();
+}

core/src/main/java/com/google/errorprone/scanner/BuiltInCheckerSuppliers.java

@@ -235,6 +235,7 @@
 import com.google.errorprone.bugpatterns.MemberName;
 import com.google.errorprone.bugpatterns.MemoizeConstantVisitorStateLookups;
 import com.google.errorprone.bugpatterns.MethodCanBeStatic;
+import com.google.errorprone.bugpatterns.MisformattedTestData;
 import com.google.errorprone.bugpatterns.MissingBraces;
 import com.google.errorprone.bugpatterns.MissingCasesInEnumSwitch;
 import com.google.errorprone.bugpatterns.MissingDefault;
@@ -997,6 +998,7 @@ public static ScannerSupplier warningChecks() {
           MalformedInlineTag.class,
           MathAbsoluteNegative.class,
           MemoizeConstantVisitorStateLookups.class,
+          MisformattedTestData.class,
           MissingCasesInEnumSwitch.class,
           MissingFail.class,
           MissingImplementsComparable.class,

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

@@ -0,0 +1,194 @@
+/*
+ * Copyright 2024 The Error Prone Authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.errorprone.bugpatterns;
+
+import static com.google.common.truth.TruthJUnit.assume;
+import static com.google.errorprone.BugCheckerRefactoringTestHelper.TestMode.TEXT_MATCH;
+
+import com.google.errorprone.BugCheckerRefactoringTestHelper;
+import com.google.errorprone.CompilationTestHelper;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.junit.runners.JUnit4;
+
+@RunWith(JUnit4.class)
+public final class MisformattedTestDataTest {
+  private final CompilationTestHelper compilationHelper =
+      CompilationTestHelper.newInstance(MisformattedTestData.class, getClass());
+  private final BugCheckerRefactoringTestHelper refactoringHelper =
+      BugCheckerRefactoringTestHelper.newInstance(MisformattedTestData.class, getClass());
+
+  @Test
+  public void alreadyFormatted_noFinding() {
+    assume().that(Runtime.version().feature()).isAtLeast(14);
+
+    compilationHelper
+        .addSourceLines(
+            "Test.java",
+            """
+            import com.google.errorprone.BugCheckerRefactoringTestHelper;
+
+            class Test {
+              void method(BugCheckerRefactoringTestHelper h) {
+                h.addInputLines(
+                    "Test.java",
+                    \"""
+                    package foo;
+
+                    class Test {
+                      void method() {
+                        int a = 1;
+                      }
+                    }
+                    \""");
+               }
+            }
+            """)
+        .doTest();
+  }
+
+  @Test
+  public void misformatted_suggestsFix() {
+    assume().that(Runtime.version().feature()).isAtLeast(14);
+
+    refactoringHelper
+        .addInputLines(
+            "Test.java",
+            """
+            import com.google.errorprone.BugCheckerRefactoringTestHelper;
+
+            class Test {
+              void method(BugCheckerRefactoringTestHelper h) {
+                h.addInputLines(
+                    "Test.java",
+                    \"""
+                    package foo;
+                    class Test {
+                      void method() {
+                        int a =
+                        1;
+                      }
+                    }
+                    \""");
+               }
+            }
+            """)
+        .addOutputLines(
+            "Test.java",
+            """
+            import com.google.errorprone.BugCheckerRefactoringTestHelper;
+
+            class Test {
+              void method(BugCheckerRefactoringTestHelper h) {
+                h.addInputLines(
+                    "Test.java",
+                    \"""
+                    package foo;
+
+                    class Test {
+                      void method() {
+                        int a = 1;
+                      }
+                    }
+                    \""");
+               }
+            }
+            """)
+        .doTest(TEXT_MATCH);
+  }
+
+  @Test
+  public void onlyDiffersByIndentation_notReindented() {
+    assume().that(Runtime.version().feature()).isAtLeast(14);
+
+    refactoringHelper
+        .addInputLines(
+            "Test.java",
+            """
+            import com.google.errorprone.BugCheckerRefactoringTestHelper;
+
+            class Test {
+              void method(BugCheckerRefactoringTestHelper h) {
+                h.addInputLines(
+                    "Test.java",
+                    \"""
+                                            package foo;
+
+                                            class Test {
+                                              void method() {
+                                                int a = 1;
+                                              }
+                                            }
+                                            ""\");
+               }
+            }
+            """)
+        .expectUnchanged()
+        .doTest(TEXT_MATCH);
+  }
+
+  @Test
+  public void escapesSpecialCharacters() {
+    assume().that(Runtime.version().feature()).isAtLeast(14);
+
+    refactoringHelper
+        .addInputLines(
+            "Test.java",
+            """
+            import com.google.errorprone.BugCheckerRefactoringTestHelper;
+
+            class Test {
+              void method(BugCheckerRefactoringTestHelper h) {
+                h.addInputLines(
+                    "Test.java",
+                    \"""
+                    package foo;
+
+                    class Test {
+                      void method() {
+                        var foo
+                            = "foo\\\\nbar";
+                      }
+                    }
+                    \""");
+               }
+            }
+            """)
+        .addOutputLines(
+            "Test.java",
+            """
+            import com.google.errorprone.BugCheckerRefactoringTestHelper;
+
+            class Test {
+              void method(BugCheckerRefactoringTestHelper h) {
+                h.addInputLines(
+                    "Test.java",
+                    \"""
+                    package foo;
+
+                    class Test {
+                      void method() {
+                        var foo = "foo\\\\nbar";
+                      }
+                    }
+                    \""");
+               }
+            }
+            """)
+        .doTest(TEXT_MATCH);
+  }
+}