diff --git a/core/tests/coretests/src/com/android/internal/util/DumpableContainerImplTest.java b/core/tests/coretests/src/com/android/internal/util/DumpableContainerImplTest.java
new file mode 100644
index 0000000000000..4c58dfa0d55d8
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+++ b/core/tests/coretests/src/com/android/internal/util/DumpableContainerImplTest.java
@@ -0,0 +1,212 @@
+/*
+ * Copyright (C) 2022 The Android Open Source Project
+ *
+ * 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.android.internal.util;
+
+import static com.google.common.truth.Truth.assertWithMessage;
+
+import static org.testng.Assert.assertThrows;
+
+import android.util.Dumpable;
+
+import com.android.internal.util.dump.DumpableContainerImpl;
+
+import org.junit.Test;
+
+import java.io.PrintWriter;
+import java.io.StringWriter;
+
+public final class DumpableContainerImplTest {
+
+    private final DumpableContainerImpl mImpl = new DumpableContainerImpl();
+    private final StringWriter mSw = new StringWriter();
+    private final PrintWriter mWriter = new PrintWriter(mSw);
+
+    @Test
+    public void testAddDumpable_null() {
+        assertThrows(NullPointerException.class, () -> mImpl.addDumpable(null));
+    }
+
+    @Test
+    public void testAddDumpable_dumpableWithoutName() {
+        Dumpable noNamer = new Dumpable() {
+
+            @Override
+            public String getDumpableName() {
+                return null;
+            }
+
+            @Override
+            public void dump(PrintWriter writer, String[] args) {
+                throw new UnsupportedOperationException("D'OH!");
+            }
+
+        };
+        assertThrows(NullPointerException.class, () -> mImpl.addDumpable(noNamer));
+    }
+
+    @Test
+    public void testListDumpables_empty() {
+        mImpl.listDumpables("...", mWriter);
+
+        assertWithMessage("listDumpables(...)").that(getOutput()).isEqualTo("...No dumpables\n");
+    }
+
+    @Test
+    public void testListDumpables_one() {
+        CustomDumpable dumpable1 = new CustomDumpable("one", "not used");
+
+        mImpl.addDumpable(dumpable1);
+        mImpl.listDumpables("...", mWriter);
+
+        assertWithMessage("listDumpables()").that(getOutput()).isEqualTo("...1 dumpables: one\n");
+    }
+
+    @Test
+    public void testListDumpables_twoDistinctNames() {
+        CustomDumpable dumpable1 = new CustomDumpable("one", "not used");
+        CustomDumpable dumpable2 = new CustomDumpable("two", "NOT USED");
+
+        boolean added1 = mImpl.addDumpable(dumpable1);
+        assertWithMessage("addDumpable(dumpable1)").that(added1).isTrue();
+
+        boolean added2 = mImpl.addDumpable(dumpable2);
+        assertWithMessage("addDumpable(dumpable2)").that(added2).isTrue();
+
+        mImpl.listDumpables("...", mWriter);
+        assertWithMessage("listDumpables()").that(getOutput())
+                .isEqualTo("...2 dumpables: one two\n");
+    }
+
+    @Test
+    public void testListDumpables_twoSameName() {
+        CustomDumpable dumpable1 = new CustomDumpable("alterego", "not used");
+        CustomDumpable dumpable2 = new CustomDumpable("alterego", "NOT USED");
+
+        boolean added1 = mImpl.addDumpable(dumpable1);
+        assertWithMessage("addDumpable(dumpable1)").that(added1).isTrue();
+
+        boolean added2 = mImpl.addDumpable(dumpable2);
+        assertWithMessage("addDumpable(dumpable2)").that(added2).isFalse();
+
+        mImpl.listDumpables("...", mWriter);
+        assertWithMessage("listDumpables()").that(getOutput())
+                .isEqualTo("...1 dumpables: alterego\n");
+    }
+
+    @Test
+    public void testOneDumpable_notFound() {
+        CustomDumpable dumpable = new CustomDumpable("one", "ONE");
+
+        mImpl.addDumpable(dumpable);
+        mImpl.dumpOneDumpable("...", mWriter, "two", /* args= */ null);
+
+        assertWithMessage("dumpOneDumpable()").that(getOutput()).isEqualTo("...No two\n");
+    }
+
+    @Test
+    public void testOneDumpable_noArgs() {
+        CustomDumpable dumpable = new CustomDumpable("The name is Bond", "James Bond!");
+
+        mImpl.addDumpable(dumpable);
+        mImpl.dumpOneDumpable("...", mWriter, "The name is Bond", /* args= */ null);
+
+        assertWithMessage("dumpOneDumpable()").that(getOutput())
+                .isEqualTo("...The name is Bond:\n"
+                        + "......James Bond!\n");
+    }
+
+    @Test
+    public void testOneDumpable_withArgs() {
+        CustomDumpable dumpable = new CustomDumpable("The name is Bond", "James Bond!");
+
+        mImpl.addDumpable(dumpable);
+        mImpl.dumpOneDumpable("...", mWriter, "The name is Bond",
+                new String[] { "Shaken", "not", "stirred" });
+
+        assertWithMessage("dumpOneDumpable()").that(getOutput())
+                .isEqualTo("...The name is Bond:\n"
+                        + "......James Bond!\n"
+                        + "......3 Args: Shaken,not,stirred,\n");
+    }
+
+    @Test
+    public void testDumpAllDumpables_noArgs() {
+        CustomDumpable dumpable1 = new CustomDumpable("one", "ONE");
+        CustomDumpable dumpable2 = new CustomDumpable("two", "TWO");
+
+        mImpl.addDumpable(dumpable1);
+        mImpl.addDumpable(dumpable2);
+        mImpl.dumpAllDumpables("...", mWriter, /* args= */ null);
+
+        assertWithMessage("dumpAllDumpables()").that(getOutput())
+                .isEqualTo("...2 dumpables:\n"
+                        + "...#0: one\n"
+                        + "......ONE\n"
+                        + "...#1: two\n"
+                        + "......TWO\n");
+    }
+
+    @Test
+    public void testDumpAllDumpables_withArgs() {
+        CustomDumpable dumpable1 = new CustomDumpable("one", "ONE");
+        CustomDumpable dumpable2 = new CustomDumpable("two", "TWO");
+
+        mImpl.addDumpable(dumpable1);
+        mImpl.addDumpable(dumpable2);
+        mImpl.dumpAllDumpables("...", mWriter, new String[] { "4", "8", "15", "16", "23", "42" });
+
+        assertWithMessage("dumpAllDumpables()").that(getOutput())
+                .isEqualTo("...2 dumpables:\n"
+                        + "...#0: one\n"
+                        + "......ONE\n"
+                        + "......6 Args: 4,8,15,16,23,42,\n"
+                        + "...#1: two\n"
+                        + "......TWO\n"
+                        + "......6 Args: 4,8,15,16,23,42,\n");
+    }
+
+    private String getOutput() {
+        mSw.flush();
+        return mSw.toString();
+    }
+
+    private static final class CustomDumpable implements Dumpable {
+        public final String name;
+        public final String content;
+
+        private CustomDumpable(String name, String content) {
+            this.name = name;
+            this.content = content;
+        }
+
+        @Override
+        public String getDumpableName() {
+            return name;
+        }
+
+        @Override
+        public void dump(PrintWriter writer, String[] args) {
+            writer.println(content);
+            if (args != null) {
+                writer.printf("%d Args: ", args.length);
+                for (String arg : args) {
+                    writer.printf("%s,", arg);
+                }
+                writer.println();
+            }
+        }
+    }
+}