chore: add unit test bash script

CONTRIBUTING.md

@@ -188,6 +188,24 @@ part before or alongside your code PR.
     pytest ./tests/unittests
     ```
 
+    **Alternatively**, use the included `unittests.sh` script which handles
+    environment setup and restoration automatically:
+
+    ```shell
+    ./unittests.sh
+    ```
+
+    This script will:
+    -   Set up the test environment with minimal dependencies (`test`, `eval`, `a2a`)
+    -   Run the unit tests
+    -   Restore the full development environment (`--all-extras`)
+
+    To also run auto-formatting after successful tests:
+
+    ```shell
+    ./unittests.sh format
+    ```
+
 6.  **Auto-format the code:**
 
     **NOTE**: We use `isort` and `pyink` for styles. Use the included

unittests.sh

@@ -0,0 +1,59 @@
+#!/bin/bash
+# Copyright 2026 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.
+
+
+# Runs all unit tests for adk codebase. Sets up dev environment re: Contributing.md
+# Usage: ./unittests.sh [format]
+#   format - Optional argument to run autoformat.sh if tests pass
+
+set -euo pipefail
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+cd "$SCRIPT_DIR"
+
+# Ensure the environment is restored if the script is interrupted.
+cleanup_on_interrupt() {
+    echo -e "\nScript interrupted. Restoring full development environment..."
+    uv sync --all-extras
+    exit 130 # Standard exit code for Ctrl+C
+}
+trap cleanup_on_interrupt INT TERM
+
+RUN_FORMAT=false
+if [[ "${1:-}" == "format" ]]; then
+    RUN_FORMAT=true
+fi
+
+echo "Setting up test environment..."
+uv sync --extra test --extra eval --extra a2a
+
+echo "Running unit tests..."
+TEST_EXIT_CODE=0
+pytest ./tests/unittests || TEST_EXIT_CODE=$?
+
+echo "Restoring full development environment..."
+uv sync --all-extras
+
+if [[ $TEST_EXIT_CODE -ne 0 ]]; then
+    echo "Unit tests failed with exit code $TEST_EXIT_CODE"
+    exit $TEST_EXIT_CODE
+fi
+
+echo "Unit tests passed!"
+
+if [[ "$RUN_FORMAT" == "true" ]]; then
+    echo "Running autoformat..."
+    ./autoformat.sh
+fi