diff --git a/core/src/main/java/google/registry/persistence/converter/VKeyConverter.java b/core/src/main/java/google/registry/persistence/converter/VKeyConverter.java
index ad2b96938..c72145c62 100644
--- a/core/src/main/java/google/registry/persistence/converter/VKeyConverter.java
+++ b/core/src/main/java/google/registry/persistence/converter/VKeyConverter.java
@@ -18,9 +18,7 @@ import google.registry.persistence.VKey;
 import javax.annotation.Nullable;
 import javax.persistence.AttributeConverter;
 
-/**
- * Converts VKey to a string column.
- */
+/** Converts VKey to a string column. */
 public abstract class VKeyConverter<T> implements AttributeConverter<VKey<T>, String> {
   @Override
   @Nullable
@@ -34,8 +32,6 @@ public abstract class VKeyConverter<T> implements AttributeConverter<VKey<T>, St
     return dbData == null ? null : VKey.createSql(getAttributeClass(), dbData);
   }
 
-  /**
-   * Returns the class of the attribute.
-   */
+  /** Returns the class of the attribute. */
   protected abstract Class<T> getAttributeClass();
 }
diff --git a/core/src/main/java/google/registry/tools/DomainLockUtils.java b/core/src/main/java/google/registry/tools/DomainLockUtils.java
index ee0bf4c4f..abb8ca794 100644
--- a/core/src/main/java/google/registry/tools/DomainLockUtils.java
+++ b/core/src/main/java/google/registry/tools/DomainLockUtils.java
@@ -153,8 +153,8 @@ public final class DomainLockUtils {
   /**
    * Creates and applies a lock in one step.
    *
-   * <p>This should only be used for admin actions, e.g. Nomulus tool commands or relocks.
-   * Note: in the case of relocks, isAdmin is determined by the previous lock.
+   * <p>This should only be used for admin actions, e.g. Nomulus tool commands or relocks. Note: in
+   * the case of relocks, isAdmin is determined by the previous lock.
    */
   public RegistryLock administrativelyApplyLock(
       String domainName, String registrarId, @Nullable String registrarPocId, boolean isAdmin) {
@@ -175,7 +175,7 @@ public final class DomainLockUtils {
 
   /**
    * Creates and applies an unlock in one step.
-   * 
+   *
    * <p>This should only be used for admin actions, e.g. Nomulus tool commands.
    */
   public RegistryLock administrativelyApplyUnlock(
diff --git a/core/src/main/java/google/registry/tools/RegistryCli.java b/core/src/main/java/google/registry/tools/RegistryCli.java
index afb33e522..2f8ee9bce 100644
--- a/core/src/main/java/google/registry/tools/RegistryCli.java
+++ b/core/src/main/java/google/registry/tools/RegistryCli.java
@@ -132,10 +132,8 @@ final class RegistryCli implements AutoCloseable, CommandRunner {
       jcommander.parse(args);
     } catch (ParameterException e) {
       // If we failed to fully parse the command but at least found a valid command name, show only
-      // the usage for that command. Otherwise, show full usage. Either way, rethrow the error.
-      if (jcommander.getParsedCommand() == null) {
-        jcommander.usage();
-      } else {
+      // the usage for that command.
+      if (jcommander.getParsedCommand() != null) {
         jcommander.usage(jcommander.getParsedCommand());
       }
       // Don't rethrow if we said: nomulus command --help
@@ -144,8 +142,13 @@ final class RegistryCli implements AutoCloseable, CommandRunner {
       }
       throw e;
     }
-
-    if (showAllCommands) {
+    String parsedCommand = jcommander.getParsedCommand();
+    // Show the list of all commands either if requested or if no subcommand name was specified
+    // (which does not throw a ParameterException parse error above).
+    if (showAllCommands || parsedCommand == null) {
+      if (parsedCommand == null) {
+        System.out.println("The list of available subcommands is:");
+      }
       commands.keySet().forEach(System.out::println);
       return;
     }
@@ -161,8 +164,7 @@ final class RegistryCli implements AutoCloseable, CommandRunner {
     // retrieving the first (and, by virtue of our usage, only) object from it.
     Command command =
         (Command)
-            Iterables.getOnlyElement(
-                jcommander.getCommands().get(jcommander.getParsedCommand()).getObjects());
+            Iterables.getOnlyElement(jcommander.getCommands().get(parsedCommand).getObjects());
     loggingParams.configureLogging();  // Must be called after parameters are parsed.
 
     try {
diff --git a/core/src/main/java/google/registry/ui/server/RegistrarFormFields.java b/core/src/main/java/google/registry/ui/server/RegistrarFormFields.java
index 46c95d411..145f94a60 100644
--- a/core/src/main/java/google/registry/ui/server/RegistrarFormFields.java
+++ b/core/src/main/java/google/registry/ui/server/RegistrarFormFields.java
@@ -186,9 +186,7 @@ public final class RegistrarFormFields {
           .build();
 
   public static final FormField<String, String> REGISTRY_LOCK_EMAIL_ADDRESS_FIELD =
-      FormFields.EMAIL
-          .asBuilderNamed("registryLockEmailAddress")
-          .build();
+      FormFields.EMAIL.asBuilderNamed("registryLockEmailAddress").build();
 
   public static final FormField<Boolean, Boolean> CONTACT_VISIBLE_IN_WHOIS_AS_ADMIN_FIELD =
       FormField.named("visibleInWhoisAsAdmin", Boolean.class)
diff --git a/core/src/nonprod/java/google/registry/tools/DumpGoldenSchemaCommand.java b/core/src/nonprod/java/google/registry/tools/DumpGoldenSchemaCommand.java
index 34586247a..d9aa1ddb9 100644
--- a/core/src/nonprod/java/google/registry/tools/DumpGoldenSchemaCommand.java
+++ b/core/src/nonprod/java/google/registry/tools/DumpGoldenSchemaCommand.java
@@ -64,8 +64,8 @@ public class DumpGoldenSchemaCommand extends PostgresqlCommand {
     if (result.getExitCode() != 0) {
       throw new RuntimeException(result.toString());
     }
-    result = postgresContainer.execInContainer(
-        "cp", CONTAINER_MOUNT_POINT_TMP, CONTAINER_MOUNT_POINT);
+    result =
+        postgresContainer.execInContainer("cp", CONTAINER_MOUNT_POINT_TMP, CONTAINER_MOUNT_POINT);
     if (result.getExitCode() != 0) {
       throw new RuntimeException(result.toString());
     }
diff --git a/core/src/test/java/google/registry/persistence/converter/VKeyConverterTest.java b/core/src/test/java/google/registry/persistence/converter/VKeyConverterTest.java
index 0f81309c5..7d22c0c79 100644
--- a/core/src/test/java/google/registry/persistence/converter/VKeyConverterTest.java
+++ b/core/src/test/java/google/registry/persistence/converter/VKeyConverterTest.java
@@ -45,8 +45,8 @@ public class VKeyConverterTest {
     jpaTm().transact(() -> jpaTm().getEntityManager().persist(original));
 
     TestEntity retrieved =
-        jpaTm().transact(
-            () -> jpaTm().getEntityManager().find(TestEntity.class, "TheRealSpartacus"));
+        jpaTm()
+            .transact(() -> jpaTm().getEntityManager().find(TestEntity.class, "TheRealSpartacus"));
     assertThat(retrieved.other.getSqlKey()).isEqualTo("ImSpartacus!");
   }
 
@@ -60,8 +60,7 @@ public class VKeyConverterTest {
 
   @Entity(name = "TestEntity")
   static class TestEntity {
-    @Id
-    String id;
+    @Id String id;
 
     // Specifying "@Converter(autoApply = true) on TestEntityVKeyConverter this doesn't seem to
     // work.
diff --git a/core/src/test/java/google/registry/tools/RegistrarContactCommandTest.java b/core/src/test/java/google/registry/tools/RegistrarContactCommandTest.java
index 45919fbf6..33e4fc6ac 100644
--- a/core/src/test/java/google/registry/tools/RegistrarContactCommandTest.java
+++ b/core/src/test/java/google/registry/tools/RegistrarContactCommandTest.java
@@ -98,19 +98,20 @@ public class RegistrarContactCommandTest extends CommandTestCase<RegistrarContac
         "--visible_in_domain_whois_as_abuse=false",
         "NewRegistrar");
     RegistrarContact registrarContact = loadRegistrar("NewRegistrar").getContacts().asList().get(1);
-    assertThat(registrarContact).isEqualTo(
-        new RegistrarContact.Builder()
-            .setParent(registrar)
-            .setName("Judith Registrar")
-            .setEmailAddress("judith.doe@example.com")
-            .setRegistryLockEmailAddress("judith.doe@external.com")
-            .setPhoneNumber("+1.2125650000")
-            .setFaxNumber("+1.2125650001")
-            .setTypes(ImmutableSet.of(WHOIS))
-            .setVisibleInWhoisAsAdmin(true)
-            .setVisibleInWhoisAsTech(false)
-            .setVisibleInDomainWhoisAsAbuse(false)
-            .build());
+    assertThat(registrarContact)
+        .isEqualTo(
+            new RegistrarContact.Builder()
+                .setParent(registrar)
+                .setName("Judith Registrar")
+                .setEmailAddress("judith.doe@example.com")
+                .setRegistryLockEmailAddress("judith.doe@external.com")
+                .setPhoneNumber("+1.2125650000")
+                .setFaxNumber("+1.2125650001")
+                .setTypes(ImmutableSet.of(WHOIS))
+                .setVisibleInWhoisAsAdmin(true)
+                .setVisibleInWhoisAsTech(false)
+                .setVisibleInDomainWhoisAsAbuse(false)
+                .build());
   }
 
   @Test
@@ -305,17 +306,18 @@ public class RegistrarContactCommandTest extends CommandTestCase<RegistrarContac
         "--visible_in_domain_whois_as_abuse=true",
         "NewRegistrar");
     RegistrarContact registrarContact = loadRegistrar("NewRegistrar").getContacts().asList().get(1);
-    assertThat(registrarContact).isEqualTo(
-        new RegistrarContact.Builder()
-            .setParent(registrar)
-            .setName("Jim Doe")
-            .setEmailAddress("jim.doe@example.com")
-            .setRegistryLockEmailAddress("jim.doe@external.com")
-            .setTypes(ImmutableSet.of(ADMIN, ABUSE))
-            .setVisibleInWhoisAsAdmin(true)
-            .setVisibleInWhoisAsTech(false)
-            .setVisibleInDomainWhoisAsAbuse(true)
-            .build());
+    assertThat(registrarContact)
+        .isEqualTo(
+            new RegistrarContact.Builder()
+                .setParent(registrar)
+                .setName("Jim Doe")
+                .setEmailAddress("jim.doe@example.com")
+                .setRegistryLockEmailAddress("jim.doe@external.com")
+                .setTypes(ImmutableSet.of(ADMIN, ABUSE))
+                .setVisibleInWhoisAsAdmin(true)
+                .setVisibleInWhoisAsTech(false)
+                .setVisibleInDomainWhoisAsAbuse(true)
+                .build());
     assertThat(registrarContact.getGaeUserId()).isNull();
   }
 
diff --git a/core/src/test/java/google/registry/tools/RegistryToolTest.java b/core/src/test/java/google/registry/tools/RegistryToolTest.java
new file mode 100644
index 000000000..aa6ac623f
--- /dev/null
+++ b/core/src/test/java/google/registry/tools/RegistryToolTest.java
@@ -0,0 +1,88 @@
+// Copyright 2020 The Nomulus Authors. All Rights Reserved.
+//
+// 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 google.registry.tools;
+
+import static com.google.common.truth.Truth.assertThat;
+import static java.nio.charset.StandardCharsets.UTF_8;
+import static org.junit.Assert.assertThrows;
+
+import google.registry.testing.AppEngineRule;
+import java.io.ByteArrayOutputStream;
+import java.io.PrintStream;
+import java.util.concurrent.locks.ReentrantLock;
+import org.junit.jupiter.api.AfterEach;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.RegisterExtension;
+
+/** Unit tests for {@link google.registry.tools.RegistryTool}. */
+public class RegistryToolTest {
+
+  @RegisterExtension
+  public final AppEngineRule appEngine = AppEngineRule.builder().withDatastoreAndCloudSql().build();
+
+  // Lock for stdout/stderr.  Note that this is static: since we're dealing with globals, we need
+  // to lock for the entire JVM.
+  private static final ReentrantLock stdoutLock = new ReentrantLock();
+
+  private PrintStream oldStdout;
+  private final ByteArrayOutputStream stdout = new ByteArrayOutputStream();
+
+  @BeforeEach
+  void beforeEach() {
+    // Capture standard output/error. This is problematic because gradle tests run in parallel in
+    // the same JVM.  So first lock out any other tests in this JVM that are trying to do this
+    // trick.
+    // TODO(mcilwain): Turn this into a JUnit 5 extension.
+    stdoutLock.lock();
+    oldStdout = System.out;
+    System.setOut(new PrintStream(stdout));
+  }
+
+  @AfterEach
+  final void afterEach() {
+    System.setOut(oldStdout);
+    stdoutLock.unlock();
+  }
+
+  @Test
+  void test_displayAvailableCommands() throws Exception {
+    RegistryTool.main(new String[] {"-e", "unittest", "--commands"});
+    // Check for the existence of a few common commands.
+    assertThat(getStdout()).contains("login");
+    assertThat(getStdout()).contains("check_domain");
+    assertThat(getStdout()).contains("get_tld");
+  }
+
+  @Test
+  void test_noSubcommandSpecified_displaysAvailableCommands() throws Exception {
+    RegistryTool.main(new String[] {"-e", "unittest"});
+    assertThat(getStdout()).contains("The list of available subcommands is:");
+    assertThat(getStdout()).contains("login");
+    assertThat(getStdout()).contains("check_domain");
+    assertThat(getStdout()).contains("get_tld");
+  }
+
+  @Test
+  void test_noEnvironmentSpecified_throwsCorrectError() {
+    IllegalArgumentException thrown =
+        assertThrows(IllegalArgumentException.class, () -> RegistryTool.main(new String[] {}));
+    assertThat(thrown).hasMessageThat().contains("Please specify the environment flag");
+  }
+
+  private String getStdout() {
+    return new String(stdout.toByteArray(), UTF_8);
+  }
+}