chore: Add conventional commits to PR body of discovery document update (#1314)

diff --git a/scripts/buildprbody_test.py b/scripts/buildprbody_test.py
new file mode 100644
index 0000000..3cc0ba5
--- /dev/null
+++ b/scripts/buildprbody_test.py
@@ -0,0 +1,65 @@
+# Copyright 2021 Google LLC
+#
+# 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.
+
+"""BuildPrBody tests."""
+
+__author__ = "partheniou@google.com (Anthonios Partheniou)"
+
+import pathlib
+import shutil
+import unittest
+
+from buildprbody import BuildPrBody
+from changesummary import ChangeType
+
+SCRIPTS_DIR = pathlib.Path(__file__).parent.resolve()
+CHANGE_SUMMARY_DIR = SCRIPTS_DIR / "test_resources" / "buildprbody_resources"
+
+EXPECTED_PR_BODY_OUTPUT = """\
+## Deleted keys were detected in the following stable discovery artifacts:
+bigquery v2 https://github.com/googleapis/google-api-python-client/commit/123
+cloudtasks v2 https://github.com/googleapis/google-api-python-client/commit/456
+
+## Discovery Artifact Change Summary:
+feat(bigquery): update the api https://github.com/googleapis/google-api-python-client/commit/123
+feat(cloudtasks): update the api https://github.com/googleapis/google-api-python-client/commit/456
+feat(drive): update the api https://github.com/googleapis/google-api-python-client/commit/789
+"""
+
+
+class TestBuildPrBody(unittest.TestCase):
+    def setUp(self):
+        self.buildprbody = BuildPrBody(change_summary_directory=CHANGE_SUMMARY_DIR)
+
+    def test_get_commit_uri_returns_correct_string(self):
+        base_uri = "https://github.com/googleapis/google-api-python-client/commit/"
+
+        expected_uri = "".join([base_uri, "123"])
+        result = self.buildprbody.get_commit_uri(name="bigquery")
+        self.assertEqual(result, expected_uri)
+
+        expected_uri = "".join([base_uri, "456"])
+        result = self.buildprbody.get_commit_uri(name="cloudtasks")
+        self.assertEqual(result, expected_uri)
+
+        expected_uri = "".join([base_uri, "789"])
+        result = self.buildprbody.get_commit_uri(name="drive")
+        self.assertEqual(result, expected_uri)
+
+    def test_generate_pr_body(self):
+        self.buildprbody.generate_pr_body()
+
+        with open(CHANGE_SUMMARY_DIR / "allapis.summary") as f:
+            pr_body = "".join(f.readlines())
+        self.assertEqual(pr_body, EXPECTED_PR_BODY_OUTPUT)