Improve log upload handling

tests/test_app.py

@@ -1,5 +1,7 @@
 import io
 
+from app import create_app
+
 
 SAMPLE_LOG = (
     'v015xxxxdate=2024-05-01 time=10:00:00 policy="Prod Policy" '
@@ -23,6 +25,7 @@ def test_index_page_loads(client):
 
 
 def test_convert_returns_text_preview_and_download_link(client):
+    log_file = io.BytesIO(SAMPLE_LOG.encode("utf-8"))
     response = client.post(
         "/convert",
         data={
@@ -34,17 +37,20 @@ def test_convert_returns_text_preview_and_download_link(client):
             "policy_ci": "prod",
             "severity_cs": "",
             "severity_ci": "",
-            "log_file": (io.BytesIO(SAMPLE_LOG.encode("utf-8")), "sample.log"),
+            "log_file": (log_file, "sample.log"),
         },
         content_type="multipart/form-data",
     )
+    log_file.close()
 
     assert response.status_code == 200
     assert b"Download export" in response.data
     assert b"--- record 1 ---" in response.data
+    response.close()
 
 
 def test_convert_full_mode_csv_preserves_union_order(client):
+    log_file = io.BytesIO(SAMPLE_LOG.encode("utf-8"))
     response = client.post(
         "/convert",
         data={
@@ -56,17 +62,20 @@ def test_convert_full_mode_csv_preserves_union_order(client):
             "policy_ci": "",
             "severity_cs": "",
             "severity_ci": "",
-            "log_file": (io.BytesIO(SAMPLE_LOG.encode("utf-8")), "sample.log"),
+            "log_file": (log_file, "sample.log"),
         },
         content_type="multipart/form-data",
     )
+    log_file.close()
 
     assert response.status_code == 200
     assert b"TEXT" not in response.data
     assert b"Download export" in response.data
+    response.close()
 
 
 def test_convert_rejects_mutually_exclusive_filters(client):
+    log_file = io.BytesIO(SAMPLE_LOG.encode("utf-8"))
     response = client.post(
         "/convert",
         data={
@@ -78,16 +87,19 @@ def test_convert_rejects_mutually_exclusive_filters(client):
             "policy_ci": "a",
             "severity_cs": "",
             "severity_ci": "",
-            "log_file": (io.BytesIO(SAMPLE_LOG.encode("utf-8")), "sample.log"),
+            "log_file": (log_file, "sample.log"),
         },
         content_type="multipart/form-data",
     )
+    log_file.close()
 
     assert response.status_code == 400
     assert b"Policy filter must use either case-sensitive or case-insensitive match" in response.data
+    response.close()
 
 
 def test_download_route_returns_generated_file(client):
+    log_file = io.BytesIO(SAMPLE_LOG.encode("utf-8"))
     convert_response = client.post(
         "/convert",
         data={
@@ -99,10 +111,11 @@ def test_download_route_returns_generated_file(client):
             "policy_ci": "",
             "severity_cs": "",
             "severity_ci": "",
-            "log_file": (io.BytesIO(SAMPLE_LOG.encode("utf-8")), "sample.log"),
+            "log_file": (log_file, "sample.log"),
         },
         content_type="multipart/form-data",
     )
+    log_file.close()
 
     html = convert_response.data.decode("utf-8")
     marker = '/download/'
@@ -115,4 +128,43 @@ def test_download_route_returns_generated_file(client):
     assert download_response.status_code == 200
     assert download_response.headers["Content-Type"].startswith("text/csv")
     assert b"v015xxxxdate,time,policy" in download_response.data
+    convert_response.close()
     download_response.close()
+
+
+def test_default_upload_limit_is_100_mib(app):
+    assert app.config["MAX_CONTENT_LENGTH"] == 100 * 1024 * 1024
+
+
+def test_too_large_upload_returns_friendly_message(tmp_path):
+    class SmallLimitConfig:
+        TESTING = True
+        SECRET_KEY = "test-secret"
+        MAX_CONTENT_LENGTH = 128
+        PREVIEW_RECORD_LIMIT = 5
+        OUTPUT_DIRECTORY = tmp_path / "tiny-limit-outputs"
+
+    app = create_app(SmallLimitConfig)
+    client = app.test_client()
+    log_file = io.BytesIO(SAMPLE_LOG.encode("utf-8"))
+
+    response = client.post(
+        "/convert",
+        data={
+            "mode": "vendor",
+            "output_format": "text",
+            "sort_by": "datetime",
+            "order": "asc",
+            "policy_cs": "",
+            "policy_ci": "",
+            "severity_cs": "",
+            "severity_ci": "",
+            "log_file": (log_file, "sample.log"),
+        },
+        content_type="multipart/form-data",
+    )
+    log_file.close()
+
+    assert response.status_code == 413
+    assert b"Maximum allowed size is 128 bytes." in response.data
+    response.close()