Rebuild the docs around tested examples; shrink README.v2.md to a pitch (#2978)

tests/docs_src/test_testing.py

@@ -0,0 +1,23 @@
+"""`docs/tutorial/testing.md`: the page's own test, run for real.
+
+The page shows this test against a `server.py` next to it; here the import path
+is the only difference.
+"""
+
+import pytest
+from inline_snapshot import snapshot
+from mcp_types import CallToolResult, TextContent
+
+from docs_src.testing.tutorial001 import mcp
+from mcp import Client
+
+# See test_index.py for why this is a per-module mark and not a conftest hook.
+pytestmark = [pytest.mark.anyio, pytest.mark.filterwarnings("error::mcp.MCPDeprecationWarning")]
+
+
+async def test_call_add_tool() -> None:
+    async with Client(mcp, raise_exceptions=True) as client:
+        result = await client.call_tool("add", {"a": 1, "b": 2})
+        assert result == snapshot(
+            CallToolResult(content=[TextContent(type="text", text="3")], structured_content={"result": 3})
+        )