diff --git a/binder/src/test/java/io/grpc/binder/PeerUidTestHelperTest.java b/binder/src/test/java/io/grpc/binder/PeerUidTestHelperTest.java
new file mode 100644
index 00000000000..6c4c95412df
--- /dev/null
+++ b/binder/src/test/java/io/grpc/binder/PeerUidTestHelperTest.java
@@ -0,0 +1,123 @@
+package io.grpc.binder;
+
+import static com.google.common.truth.Truth.assertThat;
+import static java.nio.charset.StandardCharsets.UTF_8;
+
+import com.google.common.collect.ImmutableList;
+import io.grpc.CallOptions;
+import io.grpc.Channel;
+import io.grpc.ClientInterceptors;
+import io.grpc.ManagedChannel;
+import io.grpc.Metadata;
+import io.grpc.MethodDescriptor;
+import io.grpc.ServerCallHandler;
+import io.grpc.ServerInterceptor;
+import io.grpc.ServerInterceptors;
+import io.grpc.ServerServiceDefinition;
+import io.grpc.inprocess.InProcessChannelBuilder;
+import io.grpc.inprocess.InProcessServerBuilder;
+import io.grpc.stub.ClientCalls;
+import io.grpc.stub.MetadataUtils;
+import io.grpc.stub.ServerCalls;
+import io.grpc.testing.GrpcCleanupRule;
+import java.io.ByteArrayInputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.util.concurrent.atomic.AtomicReference;
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.junit.runners.JUnit4;
+
+@RunWith(JUnit4.class)
+public final class PeerUidTestHelperTest {
+
+  @Rule
+  public final GrpcCleanupRule grpcCleanup = new GrpcCleanupRule();
+
+  private static final int FAKE_UID = 12345;
+
+  private final AtomicReference<PeerUid> clientUidCapture = new AtomicReference<>();
+
+  @Test
+  public void keyPopulatedWithInterceptorAndHeader() throws Exception {
+    makeServiceCall(/* includeInterceptor= */ true, /* includeUidInHeader= */ true, FAKE_UID);
+    assertThat(clientUidCapture.get()).isEqualTo(new PeerUid(FAKE_UID));
+  }
+
+  @Test
+  public void keyNotPopulatedWithInterceptorAndNoHeader() throws Exception {
+    makeServiceCall(/* includeInterceptor= */ true, /* includeUidInHeader= */ false, /* uid= */ -1);
+    assertThat(clientUidCapture.get()).isNull();
+  }
+
+  @Test
+  public void keyNotPopulatedWithoutInterceptorAndWithHeader() throws Exception {
+    makeServiceCall(
+        /* includeInterceptor= */ false, /* includeUidInHeader= */ true, /* uid= */ FAKE_UID);
+    assertThat(clientUidCapture.get()).isNull();
+  }
+
+  private final MethodDescriptor<String, String> method =
+      MethodDescriptor.newBuilder(StringMarshaller.INSTANCE, StringMarshaller.INSTANCE)
+          .setFullMethodName("test/method")
+          .setType(MethodDescriptor.MethodType.UNARY)
+          .build();
+
+  private void makeServiceCall(boolean includeInterceptor, boolean includeUidInHeader, int uid)
+      throws Exception {
+    ServerCallHandler<String, String> callHandler =
+        ServerCalls.asyncUnaryCall(
+            (req, respObserver) -> {
+              clientUidCapture.set(PeerUids.REMOTE_PEER.get());
+              respObserver.onNext(req);
+              respObserver.onCompleted();
+            });
+    ImmutableList<ServerInterceptor> interceptors;
+    if (includeInterceptor) {
+      interceptors = ImmutableList.of(PeerUidTestHelper.newTestPeerIdentifyingServerInterceptor());
+    } else {
+      interceptors = ImmutableList.of();
+    }
+    ServerServiceDefinition serviceDef =
+        ServerInterceptors.intercept(
+            ServerServiceDefinition.builder("test").addMethod(method, callHandler).build(),
+            interceptors);
+
+    InProcessServerBuilder server =
+        InProcessServerBuilder.forName("test").directExecutor().addService(serviceDef);
+
+    grpcCleanup.register(server.build().start());
+
+    Channel channel = InProcessChannelBuilder.forName("test").directExecutor().build();
+    grpcCleanup.register((ManagedChannel) channel);
+
+    if (includeUidInHeader) {
+      Metadata header = new Metadata();
+      header.put(PeerUidTestHelper.UID_KEY, uid);
+      channel =
+          ClientInterceptors.intercept(channel, MetadataUtils.newAttachHeadersInterceptor(header));
+    }
+
+    ClientCalls.blockingUnaryCall(channel, method, CallOptions.DEFAULT, "hello");
+  }
+
+  private static class StringMarshaller implements MethodDescriptor.Marshaller<String> {
+
+    public static final StringMarshaller INSTANCE = new StringMarshaller();
+
+    @Override
+    public InputStream stream(String value) {
+      return new ByteArrayInputStream(value.getBytes(UTF_8));
+    }
+
+    @Override
+    public String parse(InputStream stream) {
+      try {
+        return new String(stream.readAllBytes(), UTF_8);
+      } catch (IOException ex) {
+        throw new RuntimeException(ex);
+      }
+    }
+  }
+}
diff --git a/binder/src/testFixtures/java/io/grpc/binder/PeerUidTestHelper.java b/binder/src/testFixtures/java/io/grpc/binder/PeerUidTestHelper.java
new file mode 100644
index 00000000000..0492f2c1e91
--- /dev/null
+++ b/binder/src/testFixtures/java/io/grpc/binder/PeerUidTestHelper.java
@@ -0,0 +1,63 @@
+package io.grpc.binder;
+
+import io.grpc.Context;
+import io.grpc.Contexts;
+import io.grpc.Metadata;
+import io.grpc.ServerCall;
+import io.grpc.ServerCallHandler;
+import io.grpc.ServerInterceptor;
+
+/**
+ * Class which helps set up {@link PeerUids} to be used in tests.
+ */
+public final class PeerUidTestHelper {
+
+  /**
+   * The UID of the calling package is set with the value of this key.
+   */
+  public static final Metadata.Key<Integer> UID_KEY =
+      Metadata.Key.of("binder-remote-uid-for-unit-testing", PeerUidTestMarshaller.INSTANCE);
+
+  /**
+   * Creates an interceptor that associates the {@link PeerUids#REMOTE_PEER} key in the request
+   * {@link Context} with a UID provided by the client in the {@link #UID_KEY} request header, if
+   * present.
+   *
+   * <p>The returned interceptor works with any gRPC transport but is meant for in-process unit
+   * testing of gRPC/binder services that depend on {@link PeerUids}.
+   */
+  public static ServerInterceptor newTestPeerIdentifyingServerInterceptor() {
+    return new ServerInterceptor() {
+      @Override
+      public <ReqT, RespT> ServerCall.Listener<ReqT> interceptCall(
+          ServerCall<ReqT, RespT> call, Metadata headers, ServerCallHandler<ReqT, RespT> next) {
+        if (headers.containsKey(UID_KEY)) {
+          Context context =
+              Context.current().withValue(PeerUids.REMOTE_PEER, new PeerUid(headers.get(UID_KEY)));
+          return Contexts.interceptCall(context, call, headers, next);
+        }
+        return next.startCall(call, headers);
+      }
+    };
+  }
+
+  private PeerUidTestHelper() {
+  }
+
+  private static class PeerUidTestMarshaller implements Metadata.AsciiMarshaller<Integer> {
+
+    public static final PeerUidTestMarshaller INSTANCE = new PeerUidTestMarshaller();
+
+    @Override
+    public String toAsciiString(Integer value) {
+      return value.toString();
+    }
+
+    @Override
+    public Integer parseAsciiString(String serialized) {
+      return Integer.parseInt(serialized);
+    }
+  }
+
+  ;
+}