Do not use CRS operations before initializing QgsApplication [#56]

pyproject.toml

@@ -123,6 +123,7 @@ ban-relative-imports = "all"
 [tool.ruff.per-file-ignores]
 "src/pytest_qgis/pytest_qgis.py"=["PLR2004"]  # TODO: Fix magic values. Remove this after.
 "src/pytest_qgis/qgis_interface.py" = ["N802", "N803"]
+"src/pytest_qgis/utils.py" = ["ANN401"]
 "tests/*" = [
     "ANN001",
     "ANN201",

src/pytest_qgis/utils.py

@@ -43,7 +43,7 @@
 
 DEFAULT_RASTER_FORMAT = "tif"
 
-DEFAULT_CRS = QgsCoordinateReferenceSystem("EPSG:4326")
+DEFAULT_EPSG = "EPSG:4326"
 LAYER_KEYWORDS = ("layer", "lyr", "raster", "rast", "tif")
 
 
@@ -73,7 +73,7 @@ def set_map_crs_based_on_layers() -> None:
         crs_id, _ = crs_counter.most_common(1)[0]
         crs = QgsCoordinateReferenceSystem(crs_id)
     else:
-        crs = DEFAULT_CRS
+        crs = QgsCoordinateReferenceSystem(DEFAULT_EPSG)
     QgsProject.instance().setCrs(crs)
 
 
@@ -205,7 +205,7 @@ def ensure_qgis_layer_fixtures_are_cleaned(request: "FixtureRequest") -> None:
             _set_layer_owner_to_project(layer)
 
 
-def _set_layer_owner_to_project(layer: Any) -> None:  # noqa: ANN401
+def _set_layer_owner_to_project(layer: Any) -> None:
     if (
         isinstance(layer, QgsMapLayer)
         and not isinstance(layer, MagicMock)

tests/conftest.py

@@ -19,9 +19,7 @@
 from pathlib import Path
 
 import pytest
-from qgis.core import QgsCoordinateReferenceSystem, QgsRasterLayer, QgsVectorLayer
-
-from tests.utils import CRS_3067, DEFAULT_CRS
+from qgis.core import QgsRasterLayer, QgsVectorLayer
 
 pytest_plugins = "pytester"
 
@@ -65,15 +63,14 @@ def layer_polygon_session(gpkg_session: Path):
 
 @pytest.fixture()
 def layer_polygon_3067(gpkg: Path):
-    return get_gpkg_layer("polygon_3067", gpkg, CRS_3067)
+    return get_gpkg_layer("polygon_3067", gpkg)
 
 
 @pytest.fixture()
 def raster_3067():
     return get_raster_layer(
         "small raster 3067",
         Path(Path(__file__).parent, "data", "small_raster.tif"),
-        CRS_3067,
     )
 
 
@@ -89,23 +86,15 @@ def get_copied_gpkg(tmp_path: Path) -> Path:
     return new_db_path
 
 
-def get_gpkg_layer(
-    name: str, gpkg: Path, crs: QgsCoordinateReferenceSystem = DEFAULT_CRS
-) -> QgsVectorLayer:
+def get_gpkg_layer(name: str, gpkg: Path) -> QgsVectorLayer:
     layer = QgsVectorLayer(f"{gpkg!s}|layername={name}", name, "ogr")
     layer.setProviderEncoding("utf-8")
     assert layer.isValid()
-    if not layer.crs().isValid():
-        layer.setCrs(crs)
     assert layer.crs().isValid()
     return layer
 
 
-def get_raster_layer(
-    name: str, path: Path, crs: QgsCoordinateReferenceSystem = DEFAULT_CRS
-) -> QgsRasterLayer:
+def get_raster_layer(name: str, path: Path) -> QgsRasterLayer:
     layer = QgsRasterLayer(str(path), name)
     assert layer.isValid()
-    if not layer.crs().isValid():
-        layer.setCrs(crs)
     return layer

tests/test_crs.py

@@ -0,0 +1,26 @@
+import unittest
+from pathlib import Path
+
+from qgis.core import (
+    QgsCoordinateReferenceSystem,
+    QgsRasterLayer,
+)
+
+
+class TestCrs(unittest.TestCase):
+    """
+    These tests make sure CRS works as intended when pytest-qgis is active
+    """
+
+    def test_crs_copying(self):
+        crs1 = QgsCoordinateReferenceSystem("EPSG:4326")
+        assert crs1.isValid()
+        crs2 = QgsCoordinateReferenceSystem.fromWkt(crs1.toWkt())
+        assert crs1.toWkt() == crs2.toWkt()
+        assert crs2.isValid()  # <-- raises error
+
+    def test_crs_raster(self):
+        raster_path = Path(Path(__file__).parent, "data", "small_raster.tif")
+        layer = QgsRasterLayer(raster_path.as_posix())
+        assert layer.crs().toWkt()
+        assert layer.crs().isValid()

tests/test_utils.py

@@ -23,16 +23,16 @@
     replace_layers_with_reprojected_clones,
     set_map_crs_based_on_layers,
 )
-from qgis.core import QgsProject
+from qgis.core import QgsCoordinateReferenceSystem, QgsProject
 
-from tests.utils import DEFAULT_CRS, EPSG_3067, EPSG_4326, QGIS_VERSION
+from tests.utils import EPSG_3067, EPSG_4326, QGIS_VERSION
 
 QGIS_3_12 = 31200
 
 
 @pytest.fixture()
 def crs():
-    QgsProject.instance().setCrs(DEFAULT_CRS)
+    QgsProject.instance().setCrs(QgsCoordinateReferenceSystem(EPSG_4326))
 
 
 @pytest.fixture()

tests/utils.py

@@ -18,7 +18,7 @@
 #
 import os
 
-from qgis.core import Qgis, QgsCoordinateReferenceSystem
+from qgis.core import Qgis
 
 try:
     QGIS_VERSION = Qgis.versionInt()
@@ -29,6 +29,3 @@
 
 EPSG_4326 = "EPSG:4326"
 EPSG_3067 = "EPSG:3067"
-
-DEFAULT_CRS = QgsCoordinateReferenceSystem(EPSG_4326)
-CRS_3067 = QgsCoordinateReferenceSystem(EPSG_3067)