support/testing: add fastapi runtime test

Add a runtime test for fastapi. Use uvicorn as the asgi server
application as does the fastapi hello world example [1].

Fastapi depends on PydanticV2 now which is written in rust so we need to
run the test on armv7.

[1] https://fastapi.tiangolo.com/tutorial/first-steps/

Signed-off-by: Marcus Hoffmann <bubu@bubu1.eu>
[Arnout:
 - fix flake8 errors
support/testing/tests/package/sample_python_fastapi.py:5:1: E302 expected 2 blank lines, found 1
support/testing/tests/package/sample_python_fastapi.py:8:1: W391 blank line at end of file
 - Remove BR2_CCACHE (as requested by Marcus).
 - Add a comment explaining that this also tests uvicorn and pydantic.
 - Re-try wget in a loop instead of a fixed timeout of 30 seconds.
 - Add a DEVELOPERS entry.
]
Signed-off-by: Arnout Vandecappelle <arnout@mind.be>

DEVELOPERS

@@ -2064,6 +2064,10 @@ F:	package/selinux-python/
 F:	utils/config
 F:	utils/diffconfig
 
+N:	Marcus Hoffmann <bubu@bubu1.eu>
+F:	support/testing/tests/package/test_python_fastapi.py
+F:	support/testing/tests/package/sample_python_fastapi.py
+
 N:	Marek Belisko <marek.belisko@open-nandra.com>
 F:	package/libatasmart/
 F:	package/polkit/

support/testing/tests/package/sample_python_fastapi.py

@@ -0,0 +1,8 @@
+from fastapi import FastAPI
+
+app = FastAPI()
+
+
+@app.get("/")
+async def root():
+    return {"message": "Hello World"}

support/testing/tests/package/test_python_fastapi.py

@@ -0,0 +1,57 @@
+import os
+import time
+
+from tests.package.test_python import TestPythonPackageBase
+
+
+class TestPythonPy3Fastapi(TestPythonPackageBase):
+    """Test fastapi, uvicorn and pydantic2.
+
+    fastapi needs an asgi server to run. Since we select uvicorn as
+    asgi server here, uvicorn is tested as well.
+
+    pydantic is an major dependency of fastapi so it is implicitly
+    tested here as well.
+    """
+    __test__ = True
+    config = \
+        """
+        BR2_arm=y
+        BR2_cortex_a9=y
+        BR2_ARM_ENABLE_NEON=y
+        BR2_ARM_ENABLE_VFP=y
+        BR2_TOOLCHAIN_EXTERNAL=y
+        BR2_PACKAGE_PYTHON3=y
+        BR2_PACKAGE_PYTHON_FASTAPI=y
+        BR2_PACKAGE_PYTHON_UVICORN=y
+        BR2_TARGET_ROOTFS_CPIO=y
+        # BR2_TARGET_ROOTFS_TAR is not set
+        """
+    sample_scripts = ["tests/package/sample_python_fastapi.py"]
+    timeout = 60
+
+    def test_run(self):
+        self.login()
+        self.check_sample_scripts_exist()
+        cmd = "uvicorn sample_python_fastapi:app > /dev/null 2>&1 &"
+
+        _, exit_code = self.emulator.run(cmd, timeout=self.timeout)
+
+        # Give enough time for the uvicorn server to start up
+        for attempt in range(30):
+            time.sleep(1)
+
+            cmd = "wget -q -O - http://127.0.0.1:8000/"
+            output, exit_code = self.emulator.run(cmd, timeout=self.timeout)
+            if exit_code == 0:
+                self.assertEqual(output[0], '{"message":"Hello World"}')
+                break
+        else:
+            self.assertTrue(False, "Timeout while waiting for fastapi server")
+
+    def login(self):
+        cpio_file = os.path.join(self.builddir, "images", "rootfs.cpio")
+        self.emulator.boot(arch="armv7",
+                           kernel="builtin",
+                           options=["-initrd", cpio_file])
+        self.emulator.login()