test: add unit tests for STAC Zarr URL extraction

Tests asset priority logic (product > zarr > any .zarr) and error handling
for missing or malformed STAC items.

Author: wietzesuijker

tests/unit/test_get_zarr_url.py

@@ -0,0 +1,117 @@
+"""Tests for get_zarr_url.py - STAC asset URL extraction."""
+
+import json
+from unittest.mock import mock_open, patch
+
+import pytest
+
+from scripts.get_zarr_url import get_zarr_url
+
+
+class TestGetZarrUrl:
+    """Test Zarr URL extraction from STAC items."""
+
+    def test_finds_product_asset_first(self):
+        """Product asset has highest priority."""
+        stac_json = json.dumps(
+            {
+                "assets": {
+                    "product": {"href": "s3://bucket/product.zarr"},
+                    "zarr": {"href": "s3://bucket/other.zarr"},
+                    "thumbnail": {"href": "s3://bucket/random.zarr"},
+                }
+            }
+        )
+        with patch("scripts.get_zarr_url.urlopen", mock_open(read_data=stac_json.encode())):
+            url = get_zarr_url("https://stac.example.com/item")
+            assert url == "s3://bucket/product.zarr"
+
+    def test_finds_zarr_asset_second(self):
+        """Zarr asset used if no product asset."""
+        stac_json = json.dumps(
+            {
+                "assets": {
+                    "thumbnail": {"href": "s3://bucket/thumb.png"},
+                    "zarr": {"href": "s3://bucket/data.zarr"},
+                    "metadata": {"href": "s3://bucket/other.zarr"},
+                }
+            }
+        )
+        with patch("scripts.get_zarr_url.urlopen", mock_open(read_data=stac_json.encode())):
+            url = get_zarr_url("https://stac.example.com/item")
+            assert url == "s3://bucket/data.zarr"
+
+    def test_fallback_to_any_zarr_asset(self):
+        """Falls back to any asset with .zarr in href."""
+        stac_json = json.dumps(
+            {
+                "assets": {
+                    "thumbnail": {"href": "s3://bucket/thumb.png"},
+                    "data": {"href": "s3://bucket/measurements.zarr"},
+                }
+            }
+        )
+        with patch("scripts.get_zarr_url.urlopen", mock_open(read_data=stac_json.encode())):
+            url = get_zarr_url("https://stac.example.com/item")
+            assert url == "s3://bucket/measurements.zarr"
+
+    def test_no_zarr_asset_raises_error(self):
+        """Raises RuntimeError if no Zarr asset found."""
+        stac_json = json.dumps(
+            {
+                "assets": {
+                    "thumbnail": {"href": "s3://bucket/thumb.png"},
+                    "metadata": {"href": "s3://bucket/meta.json"},
+                }
+            }
+        )
+        with (
+            patch("scripts.get_zarr_url.urlopen", mock_open(read_data=stac_json.encode())),
+            pytest.raises(RuntimeError, match="No Zarr asset found"),
+        ):
+            get_zarr_url("https://stac.example.com/item")
+
+    def test_empty_assets_raises_error(self):
+        """Raises RuntimeError if assets dict is empty."""
+        stac_json = json.dumps({"assets": {}})
+        with (
+            patch("scripts.get_zarr_url.urlopen", mock_open(read_data=stac_json.encode())),
+            pytest.raises(RuntimeError, match="No Zarr asset found"),
+        ):
+            get_zarr_url("https://stac.example.com/item")
+
+    def test_missing_assets_key_raises_error(self):
+        """Raises RuntimeError if no assets key in item."""
+        stac_json = json.dumps({"id": "test-item"})
+        with (
+            patch("scripts.get_zarr_url.urlopen", mock_open(read_data=stac_json.encode())),
+            pytest.raises(RuntimeError, match="No Zarr asset found"),
+        ):
+            get_zarr_url("https://stac.example.com/item")
+
+    def test_product_asset_without_href(self):
+        """Skips product asset if no href, falls back."""
+        stac_json = json.dumps(
+            {
+                "assets": {
+                    "product": {"type": "application/json"},
+                    "data": {"href": "s3://bucket/data.zarr"},
+                }
+            }
+        )
+        with patch("scripts.get_zarr_url.urlopen", mock_open(read_data=stac_json.encode())):
+            url = get_zarr_url("https://stac.example.com/item")
+            assert url == "s3://bucket/data.zarr"
+
+    def test_handles_http_zarr_urls(self):
+        """Works with HTTP URLs for Zarr."""
+        stac_json = json.dumps(
+            {
+                "assets": {
+                    "product": {"href": "https://example.com/data.zarr"},
+                }
+            }
+        )
+        with patch("scripts.get_zarr_url.urlopen", mock_open(read_data=stac_json.encode())):
+            url = get_zarr_url("https://stac.example.com/item")
+            assert url == "https://example.com/data.zarr"