feat(block-kit): add alert block example

block-kit/README.md

@@ -9,6 +9,7 @@ Read the [docs](https://docs.slack.dev/block-kit/) to learn concepts behind thes
 ### Blocks
 
 - **[Actions](https://docs.slack.dev/reference/block-kit/blocks/actions-block)**: Holds multiple interactive elements. [Implementation](./src/blocks/actions.py).
+- **[Alert](https://docs.slack.dev/reference/block-kit/blocks/alert-block)**: Displays a notification message within a modal. [Implementation](./src/blocks/alert.py).
 - **[Context](https://docs.slack.dev/reference/block-kit/blocks/context-block)**: Provides contextual info, which can include both images and text. [Implementation](./src/blocks/context.py).
 - **[Context actions](https://docs.slack.dev/reference/block-kit/blocks/context-actions-block)**: Displays actions as contextual info, which can include both feedback buttons and icon buttons. [Implementation](./src/blocks/context_actions.py).
 - **[Divider](https://docs.slack.dev/reference/block-kit/blocks/divider-block)**: Visually separates pieces of info inside of a message. [Implementation](./src/blocks/divider.py).

block-kit/src/blocks/alert.py

@@ -0,0 +1,16 @@
+from slack_sdk.models.blocks import AlertBlock
+from slack_sdk.models.blocks.basic_components import MarkdownTextObject
+
+
+def example01() -> AlertBlock:
+    """
+    Displays a notification message within a modal.
+    https://docs.slack.dev/reference/block-kit/blocks/alert-block/
+
+    An informational alert.
+    """
+    block = AlertBlock(
+        text=MarkdownTextObject(text="The work is mysterious and important."),
+        level="info",
+    )
+    return block

block-kit/tests/blocks/test_alert.py

@@ -0,0 +1,17 @@
+import json
+
+from src.blocks import alert
+
+
+def test_example01():
+    block = alert.example01()
+    actual = block.to_dict()
+    expected = {
+        "type": "alert",
+        "text": {
+            "type": "mrkdwn",
+            "text": "The work is mysterious and important.",
+        },
+        "level": "info",
+    }
+    assert json.dumps(actual, sort_keys=True) == json.dumps(expected, sort_keys=True)