Update handling of pattern matching in switch

core/src/main/java/com/google/googlejavaformat/java/java14/Java14InputAstVisitor.java

@@ -15,6 +15,7 @@
 package com.google.googlejavaformat.java.java14;
 
 import static com.google.common.collect.ImmutableList.toImmutableList;
+import static com.google.common.collect.Iterables.getOnlyElement;
 
 import com.google.common.base.Verify;
 import com.google.common.collect.ImmutableList;
@@ -27,7 +28,6 @@
 import com.sun.source.tree.CaseTree;
 import com.sun.source.tree.ClassTree;
 import com.sun.source.tree.CompilationUnitTree;
-import com.sun.source.tree.ExpressionTree;
 import com.sun.source.tree.InstanceOfTree;
 import com.sun.source.tree.ModifiersTree;
 import com.sun.source.tree.ModuleTree;
@@ -59,6 +59,7 @@ public class Java14InputAstVisitor extends JavaInputAstVisitor {
       maybeGetMethod(BindingPatternTree.class, "getType");
   private static final Method BINDING_PATTERN_TREE_GET_BINDING =
       maybeGetMethod(BindingPatternTree.class, "getBinding");
+  private static final Method CASE_TREE_GET_LABELS = maybeGetMethod(CaseTree.class, "getLabels");
 
   public Java14InputAstVisitor(OpsBuilder builder, int indentMultiplier) {
     super(builder, indentMultiplier);
@@ -247,14 +248,25 @@ public Void visitCase(CaseTree node, Void unused) {
     sync(node);
     markForPartialFormat();
     builder.forcedBreak();
-    if (node.getExpressions().isEmpty()) {
+    List<? extends Tree> labels;
+    boolean isDefault;
+    if (CASE_TREE_GET_LABELS != null) {
+      labels = (List<? extends Tree>) invoke(CASE_TREE_GET_LABELS, node);
+      isDefault =
+          labels.size() == 1
+              && getOnlyElement(labels).getKind().name().equals("DEFAULT_CASE_LABEL");
+    } else {
+      labels = node.getExpressions();
+      isDefault = labels.isEmpty();
+    }
+    if (isDefault) {
       token("default", plusTwo);
     } else {
       token("case", plusTwo);
-      builder.open(node.getExpressions().size() > 1 ? plusFour : ZERO);
+      builder.open(labels.size() > 1 ? plusFour : ZERO);
       builder.space();
       boolean first = true;
-      for (ExpressionTree expression : node.getExpressions()) {
+      for (Tree expression : labels) {
         if (!first) {
           token(",");
           builder.breakOp(" ");

core/src/test/java/com/google/googlejavaformat/java/FormatterIntegrationTest.java

@@ -14,29 +14,28 @@
 
 package com.google.googlejavaformat.java;
 
-import static com.google.common.base.StandardSystemProperty.JAVA_CLASS_VERSION;
-import static com.google.common.base.StandardSystemProperty.JAVA_SPECIFICATION_VERSION;
+import static com.google.common.collect.MoreCollectors.toOptional;
 import static com.google.common.io.Files.getFileExtension;
 import static com.google.common.io.Files.getNameWithoutExtension;
 import static java.nio.charset.StandardCharsets.UTF_8;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertTrue;
 import static org.junit.Assert.fail;
 
-import com.google.common.collect.ImmutableSet;
+import com.google.common.collect.ImmutableMultimap;
 import com.google.common.io.CharStreams;
 import com.google.common.reflect.ClassPath;
 import com.google.common.reflect.ClassPath.ResourceInfo;
 import com.google.googlejavaformat.Newlines;
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.InputStreamReader;
-import java.lang.reflect.Method;
 import java.nio.file.Path;
 import java.nio.file.Paths;
 import java.util.ArrayList;
 import java.util.List;
 import java.util.Map;
+import java.util.Optional;
 import java.util.TreeMap;
 import org.junit.Test;
 import org.junit.runner.RunWith;
@@ -47,12 +46,13 @@
 @RunWith(Parameterized.class)
 public class FormatterIntegrationTest {
 
-  private static final ImmutableSet<String> JAVA14_TESTS =
-      ImmutableSet.of("I477", "Records", "RSLs", "Var", "ExpressionSwitch", "I574", "I594");
-
-  private static final ImmutableSet<String> JAVA15_TESTS = ImmutableSet.of("I603");
-
-  private static final ImmutableSet<String> JAVA16_TESTS = ImmutableSet.of("I588");
+  private static final ImmutableMultimap<Integer, String> VERSIONED_TESTS =
+      ImmutableMultimap.<Integer, String>builder()
+          .putAll(14, "I477", "Records", "RSLs", "Var", "ExpressionSwitch", "I574", "I594")
+          .putAll(15, "I603")
+          .putAll(16, "I588")
+          .putAll(17, "I683", "I684")
+          .build();
 
   @Parameters(name = "{index}: {0}")
   public static Iterable<Object[]> data() throws IOException {
@@ -91,35 +91,16 @@ public static Iterable<Object[]> data() throws IOException {
       String input = inputs.get(fileName);
       assertTrue("unmatched input", outputs.containsKey(fileName));
       String expectedOutput = outputs.get(fileName);
-      if (JAVA14_TESTS.contains(fileName) && getMajor() < 14) {
-        continue;
-      }
-      if (JAVA15_TESTS.contains(fileName) && getMajor() < 15) {
-        continue;
-      }
-      if (JAVA16_TESTS.contains(fileName) && getMajor() < 16) {
+      Optional<Integer> version =
+          VERSIONED_TESTS.inverse().get(fileName).stream().collect(toOptional());
+      if (version.isPresent() && Runtime.version().feature() < version.get()) {
         continue;
       }
       testInputs.add(new Object[] {fileName, input, expectedOutput});
     }
     return testInputs;
   }
 
-  private static int getMajor() {
-    try {
-      Method versionMethod = Runtime.class.getMethod("version");
-      Object version = versionMethod.invoke(null);
-      return (int) version.getClass().getMethod("major").invoke(version);
-    } catch (Exception e) {
-      // continue below
-    }
-    int version = (int) Double.parseDouble(JAVA_CLASS_VERSION.value());
-    if (49 <= version && version <= 52) {
-      return version - (49 - 5);
-    }
-    throw new IllegalStateException("Unknown Java version: " + JAVA_SPECIFICATION_VERSION.value());
-  }
-
   private final String name;
   private final String input;
   private final String expected;

core/src/test/resources/com/google/googlejavaformat/java/testdata/I683.input

@@ -0,0 +1,14 @@
+interface Test {
+
+  static class Test1 implements Test{}
+  static class Test2 implements Test{}
+
+  public static void main(String[] args) {
+    Test test = new Test1();
+    switch (test) {
+      case Test1 test1 -> {}
+      case Test2 test2 -> {}
+      default -> throw new IllegalStateException("Unexpected value: " + test);
+    }
+  }
+}

core/src/test/resources/com/google/googlejavaformat/java/testdata/I683.output

@@ -0,0 +1,15 @@
+interface Test {
+
+  static class Test1 implements Test {}
+
+  static class Test2 implements Test {}
+
+  public static void main(String[] args) {
+    Test test = new Test1();
+    switch (test) {
+      case Test1 test1 -> {}
+      case Test2 test2 -> {}
+      default -> throw new IllegalStateException("Unexpected value: " + test);
+    }
+  }
+}

core/src/test/resources/com/google/googlejavaformat/java/testdata/I684.input

@@ -0,0 +1,14 @@
+package example;
+
+import example.model.SealedInterface;
+import example.model.TypeA;
+import example.model.TypeB;
+
+public class Main {
+  public void apply(SealedInterface sealedInterface) {
+    switch(sealedInterface) {
+      case TypeA a -> System.out.println("A!");
+      case TypeB b -> System.out.println("B!");
+    }
+  }
+}

core/src/test/resources/com/google/googlejavaformat/java/testdata/I684.output

@@ -0,0 +1,14 @@
+package example;
+
+import example.model.SealedInterface;
+import example.model.TypeA;
+import example.model.TypeB;
+
+public class Main {
+  public void apply(SealedInterface sealedInterface) {
+    switch (sealedInterface) {
+      case TypeA a -> System.out.println("A!");
+      case TypeB b -> System.out.println("B!");
+    }
+  }
+}