Fix perf tests report when there are no tests (#56881)

* fix perf tests report when there are no tests

* Automatic style fix

* Update docker/test/performance-comparison/compare.sh

---------

Co-authored-by: robot-clickhouse <robot-clickhouse@users.noreply.github.com>

docker/test/performance-comparison/compare.sh

@@ -189,6 +189,8 @@ function run_tests
         test_prefix=right/performance
     fi
 
+    run_only_changed_tests=0
+
     # Determine which tests to run.
     if [ -v CHPC_TEST_GREP ]
     then
@@ -203,6 +205,7 @@ function run_tests
         # tests. The lists of changed files are prepared in entrypoint.sh because
         # it has the repository.
         test_files=($(sed "s/tests\/performance/${test_prefix//\//\\/}/" changed-test-definitions.txt))
+        run_only_changed_tests=1
     else
         # The default -- run all tests found in the test dir.
         test_files=($(ls "$test_prefix"/*.xml))
@@ -226,6 +229,13 @@ function run_tests
         test_files=("${test_files[@]}")
     fi
 
+    if [ "$run_only_changed_tests" -ne 0 ]; then
+        if [ ${#test_files[@]} -eq 0 ]; then
+            time "$script_dir/report.py" --no-tests-run > report.html
+            exit 0
+        fi
+    fi
+
     # For PRs w/o changes in test definitons, test only a subset of queries,
     # and run them less times. If the corresponding environment variables are
     # already set, keep those values.

docker/test/performance-comparison/report.py

@@ -19,6 +19,7 @@ parser.add_argument(
     choices=["main", "all-queries"],
     help="Which report to build",
 )
+parser.add_argument("--no-tests-run", action="store_true", default=False)
 args = parser.parse_args()
 
 tables = []
@@ -354,6 +355,36 @@ if args.report == "main":
 
     add_tested_commits()
 
+    def print_status(status, message):
+        print(
+            (
+                """
+        <!--status: {status}-->
+        <!--message: {message}-->
+        """.format(
+                    status=status, message=message
+                )
+            )
+        )
+
+    if args.no_tests_run:
+        for t in tables:
+            print(t)
+        print(
+            "<h2>No tests to run. Only changed tests were run, but all changed tests are from another batch.</h2>"
+        )
+        print(
+            f"""
+        </div>
+        {os.getenv("CHPC_ADD_REPORT_LINKS") or ''}
+        </body>
+        </html>
+        """
+        )
+        # Why failure? Because otherwise we will not notice if we have a bug that leads to 0 tests being run
+        print_status("failure", "No tests changed, nothing to run")
+        exit(0)
+
     run_error_rows = tsvRows("run-errors.tsv")
     error_tests += len(run_error_rows)
     addSimpleTable("Run Errors", ["Test", "Error"], run_error_rows)
@@ -646,16 +677,7 @@ if args.report == "main":
         status = "failure"
         message = "Errors while building the report."
 
-    print(
-        (
-            """
-    <!--status: {status}-->
-    <!--message: {message}-->
-    """.format(
-                status=status, message=message
-            )
-        )
-    )
+    print_status(status, message)
 
 elif args.report == "all-queries":
     print((header_template.format()))