tests: Make tests runnable from anywhere

By using the current file rather than the root of the project as the
reference, the tests are now runnable for example in an IDE which uses
the "tests" directory as the root.

Author: l0b0

tests/test_catalog.py

@@ -939,7 +939,7 @@ def test_collections_cache_correctly(self) -> None:
 
     def test_reading_iterating_and_writing_works_as_expected(self) -> None:
         """Test case to cover issue #88"""
-        stac_uri = "tests/data-files/catalogs/test-case-6/catalog.json"
+        stac_uri = TestCases.get_path("data-files/catalogs/test-case-6/catalog.json")
         cat = Catalog.from_file(stac_uri)
 
         # Iterate over the items. This was causing failure in

tests/test_item_collection.py

@@ -2,6 +2,8 @@
 import json
 from pystac.item_collection import ItemCollection
 import unittest
+from os.path import relpath
+
 import pystac
 
 from tests.utils import TestCases
@@ -101,7 +103,11 @@ def test_raise_error_for_invalid_object(self) -> None:
 
     def test_from_relative_path(self) -> None:
         _ = pystac.ItemCollection.from_file(
-            "./tests/data-files/item-collection/sample-item-collection.json"
+            relpath(
+                TestCases.get_path(
+                    "data-files/item-collection/sample-item-collection.json"
+                )
+            )
         )
 
     def test_from_list_of_dicts(self) -> None:

tests/test_utils.py

@@ -8,6 +8,7 @@
 from pystac import utils
 
 from pystac.utils import make_relative_href, make_absolute_href, is_absolute_href
+from tests.utils import TestCases
 
 
 class UtilsTest(unittest.TestCase):
@@ -273,7 +274,9 @@ def test_datetime_to_str(self) -> None:
 
     def test_geojson_bbox(self) -> None:
         # Use sample Geojson from https://en.wikipedia.org/wiki/GeoJSON
-        with open("tests/data-files/geojson/sample.geojson") as sample_geojson:
+        with open(
+            TestCases.get_path("data-files/geojson/sample.geojson")
+        ) as sample_geojson:
             all_features = json.load(sample_geojson)
             geom_dicts = [f["geometry"] for f in all_features["features"]]
             for geom in geom_dicts: