[ci] Check for trailing newlines and spaces

This adds a short lint to ensure that all files have a single trailing
newline and no trailing whitespaces.

ci/scripts/git_skip_ci_globs.py

@@ -35,6 +35,8 @@
     # microTVM
     "apps/microtvm/poetry.lock",
     "apps/microtvm/pyproject.toml",
+    "tests/lint/*",
+    "tests/scripts/task_lint.sh",
 ]
 
 

tests/lint/trailing_newlines.py

@@ -0,0 +1,51 @@
+#!/usr/bin/env python3
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you 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 fileinput
+import os
+
+
+def has_one_trailing_newline(filename: str) -> bool:
+    """
+    Returns True if 'filename' has a single trailing newline
+    """
+    with open(filename, "rb") as f:
+        start_bytes = len(f.read(2))
+        if start_bytes == 0:
+            # empty file
+            return True
+        elif start_bytes == 1:
+            # 1 byte file
+            return False
+        else:
+            # skip to the end
+            f.seek(-2, os.SEEK_END)
+            end_bytes = f.read(2)
+
+            # should be a non-newline followed by a newline
+            return end_bytes[0] != ord("\n") and end_bytes[1] == ord("\n")
+
+
+if __name__ == "__main__":
+    exit_code = 1
+    for line in fileinput.input():
+        filename = line.rstrip()
+        if not has_one_trailing_newline(filename):
+            exit_code = 0
+            print(filename)
+    exit(exit_code)

tests/lint/whitespace.sh

@@ -0,0 +1,39 @@
+#!/usr/bin/env bash
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you 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.
+
+set -euo pipefail
+
+status=0
+
+if git --no-pager grep -Il '' -- . | ./tests/lint/trailing_newlines.py; then
+    echo "The above files are missing a trailing newline or have too many trailing newlines"
+    status=1
+fi
+
+if git --no-pager grep -In '[[:blank:]]$' -- .; then
+    echo "The above files have trailing spaces"
+    status=1
+fi
+
+if [ $status == "1" ]; then
+    echo "Found whitespace lint failures, 'pre-commit run --all-files' can auto-correct them"
+    exit 1
+else
+    echo "Found no whitespace lint failures"
+    exit 0
+fi

tests/scripts/task_lint.sh

@@ -60,6 +60,9 @@ function shard1 {
 }
 
 function shard2 {
+  echo "check whitespace..."
+  tests/lint/whitespace.sh
+
   echo "Linting the Python code with pylint..."
   tests/lint/pylint.sh