Add import tests (#1945)

Author: moshemorad

tests/test_app_imports.py

@@ -0,0 +1,35 @@
+import os
+import pytest
+
+EXPECTED_LINES = [
+    "import os\n",
+    "\n",
+    "from robusta.runner.ssl_utils import add_custom_certificate\n",
+    "\n",
+    'ADDITIONAL_CERTIFICATE: str = os.environ.get("CERTIFICATE", "")\n',
+    "\n",
+    "if add_custom_certificate(ADDITIONAL_CERTIFICATE):\n",
+    '    print("added custom certificate")\n',
+    "\n",
+    "# DO NOT ADD ANY CODE ABOVE THIS\n",
+    "# ADDING IMPORTS BEFORE ADDING THE CUSTOM CERTS MIGHT INIT HTTP CLIENTS THAT DOESN'T RESPECT THE CUSTOM CERT\n",
+]
+
+
+@pytest.mark.parametrize(
+    "file_path,file_name",
+    [
+        ("src/robusta/runner/main.py", "main.py"),
+    ],
+)
+def test_app_files_have_correct_initial_lines(file_path, file_name):
+    """Test that app files start with the required certificate handling code."""
+    full_path = os.path.join(os.path.dirname(__file__), "..", file_path)
+
+    with open(full_path, "r") as f:
+        lines = f.readlines()
+
+    for i, expected_line in enumerate(EXPECTED_LINES):
+        assert (
+            lines[i] == expected_line
+        ), f"Line {i + 1} should be: {expected_line.strip()!r}, but got: {lines[i].strip()!r}. This tests make sure the import order in {file_name} file is correct, if you see this, go to {file_name} file and move your imports code to lower lines."