diff --git a/tools/sbom/sbom_writers_test.py b/tools/sbom/sbom_writers_test.py
new file mode 100644
index 0000000..4db2bb7
--- /dev/null
+++ b/tools/sbom/sbom_writers_test.py
@@ -0,0 +1,153 @@
+#!/usr/bin/env python3
+#
+# Copyright (C) 2023 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.
+
+import io
+import pathlib
+import unittest
+import sbom_data
+import sbom_writers
+
+BUILD_FINGER_PRINT = 'build_finger_print'
+SUPPLIER_GOOGLE = 'Organization: Google'
+SUPPLIER_UPSTREAM = 'Organization: upstream'
+
+SPDXID_PREBUILT_PACKAGE1 = 'SPDXRef-PREBUILT-package1'
+SPDXID_SOURCE_PACKAGE1 = 'SPDXRef-SOURCE-package1'
+SPDXID_UPSTREAM_PACKAGE1 = 'SPDXRef-UPSTREAM-package1'
+
+SPDXID_FILE1 = 'SPDXRef-file1'
+SPDXID_FILE2 = 'SPDXRef-file2'
+SPDXID_FILE3 = 'SPDXRef-file3'
+
+
+class SBOMWritersTest(unittest.TestCase):
+
+  def setUp(self):
+    # SBOM of a product
+    self.sbom_doc = sbom_data.Document(name='test doc',
+                                       namespace='http://www.google.com/sbom/spdx/android',
+                                       creators=[SUPPLIER_GOOGLE],
+                                       created='2023-03-31T22:17:58Z',
+                                       describes=sbom_data.SPDXID_PRODUCT)
+    self.sbom_doc.add_external_ref(
+      sbom_data.DocumentExternalReference(id='DocumentRef-external_doc_ref',
+                                          uri='external_doc_uri',
+                                          checksum='SHA1: 1234567890'))
+    self.sbom_doc.add_package(
+      sbom_data.Package(id=sbom_data.SPDXID_PRODUCT,
+                        name=sbom_data.PACKAGE_NAME_PRODUCT,
+                        supplier=SUPPLIER_GOOGLE,
+                        version=BUILD_FINGER_PRINT,
+                        files_analyzed=True,
+                        verification_code='123456',
+                        file_ids=[SPDXID_FILE1, SPDXID_FILE2, SPDXID_FILE3]))
+
+    self.sbom_doc.add_package(
+      sbom_data.Package(id=sbom_data.SPDXID_PLATFORM,
+                        name=sbom_data.PACKAGE_NAME_PLATFORM,
+                        supplier=SUPPLIER_GOOGLE,
+                        version=BUILD_FINGER_PRINT,
+                        ))
+
+    self.sbom_doc.add_package(
+      sbom_data.Package(id=SPDXID_PREBUILT_PACKAGE1,
+                        name='Prebuilt package1',
+                        supplier=SUPPLIER_GOOGLE,
+                        version=BUILD_FINGER_PRINT,
+                        ))
+
+    self.sbom_doc.add_package(
+      sbom_data.Package(id=SPDXID_SOURCE_PACKAGE1,
+                        name='Source package1',
+                        supplier=SUPPLIER_GOOGLE,
+                        version=BUILD_FINGER_PRINT,
+                        external_refs=[sbom_data.PackageExternalRef(
+                          category=sbom_data.PackageExternalRefCategory.SECURITY,
+                          type=sbom_data.PackageExternalRefType.cpe22Type,
+                          locator='cpe:/a:jsoncpp_project:jsoncpp:1.9.4')]
+                        ))
+
+    self.sbom_doc.add_package(
+      sbom_data.Package(id=SPDXID_UPSTREAM_PACKAGE1,
+                        name='Upstream package1',
+                        supplier=SUPPLIER_UPSTREAM,
+                        version='1.1',
+                        ))
+
+    self.sbom_doc.add_relationship(sbom_data.Relationship(id1=SPDXID_SOURCE_PACKAGE1,
+                                                          relationship=sbom_data.RelationshipType.VARIANT_OF,
+                                                          id2=SPDXID_UPSTREAM_PACKAGE1))
+
+    self.sbom_doc.files.append(
+      sbom_data.File(id=SPDXID_FILE1, name='/bin/file1', checksum='SHA1: 11111'))
+    self.sbom_doc.files.append(
+      sbom_data.File(id=SPDXID_FILE2, name='/bin/file2', checksum='SHA1: 22222'))
+    self.sbom_doc.files.append(
+      sbom_data.File(id=SPDXID_FILE3, name='/bin/file3', checksum='SHA1: 33333'))
+
+    self.sbom_doc.add_relationship(sbom_data.Relationship(id1=SPDXID_FILE1,
+                                                          relationship=sbom_data.RelationshipType.GENERATED_FROM,
+                                                          id2=sbom_data.SPDXID_PLATFORM))
+    self.sbom_doc.add_relationship(sbom_data.Relationship(id1=SPDXID_FILE2,
+                                                          relationship=sbom_data.RelationshipType.GENERATED_FROM,
+                                                          id2=SPDXID_PREBUILT_PACKAGE1))
+    self.sbom_doc.add_relationship(sbom_data.Relationship(id1=SPDXID_FILE3,
+                                                          relationship=sbom_data.RelationshipType.GENERATED_FROM,
+                                                          id2=SPDXID_SOURCE_PACKAGE1
+                                                          ))
+
+    # SBOM fragment of a APK
+    self.unbundled_sbom_doc = sbom_data.Document(name='test doc',
+                                                 namespace='http://www.google.com/sbom/spdx/android',
+                                                 creators=[SUPPLIER_GOOGLE],
+                                                 created='2023-03-31T22:17:58Z',
+                                                 describes=SPDXID_FILE1)
+
+    self.unbundled_sbom_doc.files.append(
+      sbom_data.File(id=SPDXID_FILE1, name='/bin/file1.apk', checksum='SHA1: 11111'))
+    self.unbundled_sbom_doc.add_package(
+      sbom_data.Package(id=SPDXID_SOURCE_PACKAGE1,
+                        name='Unbundled apk package',
+                        supplier=SUPPLIER_GOOGLE,
+                        version=BUILD_FINGER_PRINT))
+    self.unbundled_sbom_doc.add_relationship(sbom_data.Relationship(id1=SPDXID_FILE1,
+                                                                    relationship=sbom_data.RelationshipType.GENERATED_FROM,
+                                                                    id2=SPDXID_SOURCE_PACKAGE1))
+
+  def test_tagvalue_writer(self):
+    with io.StringIO() as output:
+      sbom_writers.TagValueWriter.write(self.sbom_doc, output)
+      expected_output = pathlib.Path('testdata/expected_tagvalue_sbom.spdx').read_text()
+      self.maxDiff = None
+      self.assertEqual(expected_output, output.getvalue())
+
+  def test_tagvalue_writer_unbundled(self):
+    with io.StringIO() as output:
+      sbom_writers.TagValueWriter.write(self.unbundled_sbom_doc, output, fragment=True)
+      expected_output = pathlib.Path('testdata/expected_tagvalue_sbom_unbundled.spdx').read_text()
+      self.maxDiff = None
+      self.assertEqual(expected_output, output.getvalue())
+
+  def test_json_writer(self):
+    with io.StringIO() as output:
+      sbom_writers.JSONWriter.write(self.sbom_doc, output)
+      expected_output = pathlib.Path('testdata/expected_json_sbom.spdx.json').read_text()
+      self.maxDiff = None
+      self.assertEqual(expected_output, output.getvalue())
+
+
+if __name__ == '__main__':
+  unittest.main(verbosity=2)