google · kamilkrzywanski · Jul 20, 2026
diff --git a/jimfs/pom.xml b/jimfs/pom.xml
@@ -68,8 +68,8 @@
 
     <!-- Test dependencies -->
     <dependency>
-      <groupId>junit</groupId>
-      <artifactId>junit</artifactId>
+      <groupId>org.junit.jupiter</groupId>
+      <artifactId>junit-jupiter</artifactId>
     </dependency>
     <dependency>
       <groupId>com.google.guava</groupId>

diff --git a/jimfs/src/test/java/com/google/common/jimfs/AbstractAttributeProviderTest.java b/jimfs/src/test/java/com/google/common/jimfs/AbstractAttributeProviderTest.java
@@ -17,14 +17,14 @@
 package com.google.common.jimfs;
 
 import static com.google.common.truth.Truth.assertThat;
-import static org.junit.Assert.fail;
+import static org.junit.jupiter.api.Assertions.assertThrows;
 
 import com.google.common.collect.ImmutableMap;
 import java.io.IOException;
 import java.nio.file.attribute.FileAttributeView;
 import java.util.Map;
 import java.util.Set;
-import org.junit.Before;
+import org.junit.jupiter.api.BeforeEach;
 
 /**
  * Abstract base class for tests of individual {@link AttributeProvider} implementations.
@@ -56,7 +56,7 @@ public File lookup() throws IOException {
     };
   }
 
-  @Before
+  @BeforeEach
   public void setUp() {
     this.provider = createProvider();
     this.file = Directory.create(0, fileTimeSource.now());
@@ -115,21 +115,15 @@ protected void assertSetAndGetSucceedsOnCreate(String attribute, Object value) {
     assertSetAndGetSucceeds(attribute, value, true);
   }
 
-  @SuppressWarnings("EmptyCatchBlock")
   protected void assertSetFails(String attribute, Object value) {
-    try {
-      provider.set(file, provider.name(), attribute, value, false);
-      fail();
-    } catch (IllegalArgumentException expected) {
-    }
+    assertThrows(
+        IllegalArgumentException.class,
+        () -> provider.set(file, provider.name(), attribute, value, false));
   }
 
-  @SuppressWarnings("EmptyCatchBlock")
   protected void assertSetFailsOnCreate(String attribute, Object value) {
-    try {
-      provider.set(file, provider.name(), attribute, value, true);
-      fail();
-    } catch (UnsupportedOperationException expected) {
-    }
+    assertThrows(
+        UnsupportedOperationException.class,
+        () -> provider.set(file, provider.name(), attribute, value, true));
   }
 }
diff --git a/jimfs/src/test/java/com/google/common/jimfs/AbstractGlobMatcherTest.java b/jimfs/src/test/java/com/google/common/jimfs/AbstractGlobMatcherTest.java
@@ -16,7 +16,7 @@
 
 package com.google.common.jimfs;
 
-import org.junit.Test;
+import org.junit.jupiter.api.Test;
 
 /** @author Colin Decker */
 public abstract class AbstractGlobMatcherTest extends AbstractPathMatcherTest {

diff --git a/jimfs/src/test/java/com/google/common/jimfs/AbstractJimfsIntegrationTest.java b/jimfs/src/test/java/com/google/common/jimfs/AbstractJimfsIntegrationTest.java
@@ -27,20 +27,20 @@
 import java.nio.file.Path;
 import java.nio.file.attribute.BasicFileAttributes;
 import java.nio.file.attribute.FileTime;
-import org.junit.After;
-import org.junit.Before;
+import org.junit.jupiter.api.AfterEach;
+import org.junit.jupiter.api.BeforeEach;
 
 /** @author Colin Decker */
 public abstract class AbstractJimfsIntegrationTest {
 
   protected FileSystem fs;
 
-  @Before
+  @BeforeEach
   public void setUp() throws IOException {
     fs = createFileSystem();
   }
 
-  @After
+  @AfterEach
   public void tearDown() throws IOException {
     fs.close();
   }

diff --git a/jimfs/src/test/java/com/google/common/jimfs/AbstractPathMatcherTest.java b/jimfs/src/test/java/com/google/common/jimfs/AbstractPathMatcherTest.java
@@ -16,9 +16,10 @@
 
 package com.google.common.jimfs;
 
-import static org.junit.Assert.assertFalse;
-import static org.junit.Assert.assertTrue;
-import static org.junit.Assert.fail;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+import static org.junit.jupiter.api.Assertions.fail;
 
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
 import java.io.File;
@@ -54,11 +55,7 @@ public abstract class AbstractPathMatcherTest {
   }
 
   protected void assertSyntaxError(String pattern) {
-    try {
-      matcher(pattern);
-      fail();
-    } catch (PatternSyntaxException expected) {
-    }
+    assertThrows(PatternSyntaxException.class, () -> matcher(pattern));
 
     try {
       PathMatcher real = realMatcher(pattern);
@@ -88,12 +85,13 @@ protected final class PatternAsserter {
     PatternAsserter matches(String... paths) {
       for (String path : paths) {
         assertTrue(
-            "matcher '" + matcher + "' did not match '" + path + "'", matcher.matches(fake(path)));
+            matcher.matches(fake(path)),
+            "matcher '" + matcher + "' did not match '" + path + "'");
         if (realMatcher != null) {
           Path realPath = Paths.get(path);
           assertTrue(
-              "real matcher '" + realMatcher + "' did not match '" + realPath + "'",
-              realMatcher.matches(realPath));
+              realMatcher.matches(realPath),
+              "real matcher '" + realMatcher + "' did not match '" + realPath + "'");
         }
       }
       return this;
@@ -103,13 +101,13 @@ PatternAsserter matches(String... paths) {
     PatternAsserter doesNotMatch(String... paths) {
       for (String path : paths) {
         assertFalse(
-            "glob '" + matcher + "' should not have matched '" + path + "'",
-            matcher.matches(fake(path)));
+            matcher.matches(fake(path)),
+            "glob '" + matcher + "' should not have matched '" + path + "'");
         if (realMatcher != null) {
           Path realPath = Paths.get(path);
           assertFalse(
-              "real matcher '" + realMatcher + "' matched '" + realPath + "'",
-              realMatcher.matches(realPath));
+              realMatcher.matches(realPath),
+              "real matcher '" + realMatcher + "' matched '" + realPath + "'");
         }
       }
       return this;

diff --git a/jimfs/src/test/java/com/google/common/jimfs/AbstractWatchServiceTest.java b/jimfs/src/test/java/com/google/common/jimfs/AbstractWatchServiceTest.java
@@ -24,7 +24,7 @@
 import static java.nio.file.StandardWatchEventKinds.ENTRY_MODIFY;
 import static java.nio.file.StandardWatchEventKinds.OVERFLOW;
 import static java.util.concurrent.TimeUnit.SECONDS;
-import static org.junit.Assert.assertThrows;
+import static org.junit.jupiter.api.Assertions.assertThrows;
 
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableSet;
@@ -37,22 +37,19 @@
 import java.nio.file.Watchable;
 import java.util.Arrays;
 import java.util.List;
-import org.junit.Before;
-import org.junit.Test;
-import org.junit.runner.RunWith;
-import org.junit.runners.JUnit4;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
 
 /**
  * Tests for {@link AbstractWatchService}.
  *
  * @author Colin Decker
  */
-@RunWith(JUnit4.class)
 public class AbstractWatchServiceTest {
 
   private AbstractWatchService watcher;
 
-  @Before
+  @BeforeEach
   public void setUp() throws IOException {
     watcher = new AbstractWatchService() {};
   }

diff --git a/jimfs/src/test/java/com/google/common/jimfs/AclAttributeProviderTest.java b/jimfs/src/test/java/com/google/common/jimfs/AclAttributeProviderTest.java
@@ -22,7 +22,7 @@
 import static java.nio.file.attribute.AclEntryPermission.APPEND_DATA;
 import static java.nio.file.attribute.AclEntryPermission.DELETE;
 import static java.nio.file.attribute.AclEntryType.ALLOW;
-import static org.junit.Assert.assertNotNull;
+import static org.junit.jupiter.api.Assertions.assertNotNull;
 
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableMap;
@@ -34,16 +34,13 @@
 import java.nio.file.attribute.UserPrincipal;
 import java.util.Map;
 import java.util.Set;
-import org.junit.Test;
-import org.junit.runner.RunWith;
-import org.junit.runners.JUnit4;
+import org.junit.jupiter.api.Test;
 
 /**
  * Tests for {@link AclAttributeProvider}.
  *
  * @author Colin Decker
  */
-@RunWith(JUnit4.class)
 public class AclAttributeProviderTest extends AbstractAttributeProviderTest<AclAttributeProvider> {
 
   private static final UserPrincipal USER = createUserPrincipal("user");

diff --git a/jimfs/src/test/java/com/google/common/jimfs/AttributeServiceTest.java b/jimfs/src/test/java/com/google/common/jimfs/AttributeServiceTest.java
@@ -17,7 +17,7 @@
 package com.google.common.jimfs;
 
 import static com.google.common.truth.Truth.assertThat;
-import static org.junit.Assert.assertThrows;
+import static org.junit.jupiter.api.Assertions.assertThrows;
 
 import com.google.common.collect.ImmutableMap;
 import com.google.common.collect.ImmutableSet;
@@ -28,24 +28,21 @@
 import java.nio.file.attribute.FileTime;
 import java.nio.file.attribute.PosixFileAttributeView;
 import java.nio.file.attribute.PosixFileAttributes;
-import org.junit.Before;
-import org.junit.Test;
-import org.junit.runner.RunWith;
-import org.junit.runners.JUnit4;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
 
 /**
  * Tests for {@link AttributeService}.
  *
  * @author Colin Decker
  */
-@RunWith(JUnit4.class)
 public class AttributeServiceTest {
 
   private AttributeService service;
 
   private final FakeFileTimeSource fileTimeSource = new FakeFileTimeSource();
 
-  @Before
+  @BeforeEach
   public void setUp() {
     ImmutableSet<AttributeProvider> providers =
         ImmutableSet.of(

diff --git a/jimfs/src/test/java/com/google/common/jimfs/BasicAttributeProviderTest.java b/jimfs/src/test/java/com/google/common/jimfs/BasicAttributeProviderTest.java
@@ -25,16 +25,13 @@
 import java.nio.file.attribute.BasicFileAttributes;
 import java.nio.file.attribute.FileTime;
 import java.util.Set;
-import org.junit.Test;
-import org.junit.runner.RunWith;
-import org.junit.runners.JUnit4;
+import org.junit.jupiter.api.Test;
 
 /**
  * Tests for {@link BasicAttributeProvider}.
  *
  * @author Colin Decker
  */
-@RunWith(JUnit4.class)
 public class BasicAttributeProviderTest
     extends AbstractAttributeProviderTest<BasicAttributeProvider> {
 

diff --git a/jimfs/src/test/java/com/google/common/jimfs/ClassLoaderTest.java b/jimfs/src/test/java/com/google/common/jimfs/ClassLoaderTest.java
@@ -17,9 +17,9 @@
 package com.google.common.jimfs;
 
 import static java.nio.charset.StandardCharsets.UTF_8;
-import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.assertFalse;
-import static org.junit.Assert.assertTrue;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertTrue;
 
 import com.google.common.base.MoreObjects;
 import com.google.common.collect.ImmutableList;
@@ -31,9 +31,7 @@
 import java.nio.file.Path;
 import java.nio.file.spi.FileSystemProvider;
 import java.util.List;
-import org.junit.Test;
-import org.junit.runner.RunWith;
-import org.junit.runners.JUnit4;
+import org.junit.jupiter.api.Test;
 
 /**
  * Tests behavior when user code loads Jimfs in a separate class loader from the system class loader
@@ -42,7 +40,6 @@
  *
  * @author Colin Decker
  */
-@RunWith(JUnit4.class)
 public class ClassLoaderTest {
 
   @Test

diff --git a/jimfs/src/test/java/com/google/common/jimfs/ConfigurationTest.java b/jimfs/src/test/java/com/google/common/jimfs/ConfigurationTest.java
@@ -26,8 +26,7 @@
 import static com.google.common.truth.Truth.assert_;
 import static java.util.concurrent.TimeUnit.MILLISECONDS;
 import static java.util.concurrent.TimeUnit.SECONDS;
-import static org.junit.Assert.assertThrows;
-import static org.junit.Assert.fail;
+import static org.junit.jupiter.api.Assertions.assertThrows;
 
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.Iterables;
@@ -38,17 +37,14 @@
 import java.nio.file.Path;
 import java.nio.file.WatchService;
 import java.nio.file.attribute.PosixFilePermissions;
-import org.junit.Test;
-import org.junit.runner.RunWith;
-import org.junit.runners.JUnit4;
+import org.junit.jupiter.api.Test;
 
 /**
  * Tests for {@link Configuration}, {@link Configuration.Builder} and file systems created from
  * them.
  *
  * @author Colin Decker
  */
-@RunWith(JUnit4.class)
 public class ConfigurationTest {
 
   private static PathSubject assertThatPath(Path path) {
@@ -268,11 +264,9 @@ public void testSettingRootsUnsupportedByPathType() {
   }
 
   private static void assertIllegalRoots(PathType type, String first, String... more) {
-    try {
-      Configuration.builder(type).setRoots(first, more); // wrong root
-      fail();
-    } catch (IllegalArgumentException expected) {
-    }
+    assertThrows(
+        IllegalArgumentException.class,
+        () -> Configuration.builder(type).setRoots(first, more)); // wrong root
   }
 
   @Test
@@ -296,17 +290,13 @@ public void testSettingNormalizationWhenNormalizationAlreadySet() {
 
   private static void assertIllegalNormalizations(
       PathNormalization first, PathNormalization... more) {
-    try {
-      Configuration.builder(PathType.unix()).setNameCanonicalNormalization(first, more);
-      fail();
-    } catch (IllegalArgumentException expected) {
-    }
-
-    try {
-      Configuration.builder(PathType.unix()).setNameDisplayNormalization(first, more);
-      fail();
-    } catch (IllegalArgumentException expected) {
-    }
+    assertThrows(
+        IllegalArgumentException.class,
+        () -> Configuration.builder(PathType.unix()).setNameCanonicalNormalization(first, more));
+
+    assertThrows(
+        IllegalArgumentException.class,
+        () -> Configuration.builder(PathType.unix()).setNameDisplayNormalization(first, more));
   }
 
   @Test

diff --git a/jimfs/src/test/java/com/google/common/jimfs/CrossClassLoaderAccessTest.java b/jimfs/src/test/java/com/google/common/jimfs/CrossClassLoaderAccessTest.java
@@ -21,7 +21,7 @@
 import java.net.URLClassLoader;
 import java.nio.file.Path;
 import java.nio.file.Paths;
-import org.junit.Test;
+import org.junit.jupiter.api.Test;
 
 /**
  * A test that the {@code toPath} method of {@link SystemJimfsFileSystemProvider} handles the case