diff --git a/.github/workflows/tests-conda.yml b/.github/workflows/tests-conda.yml
index 43e5d22a..4d635041 100644
--- a/.github/workflows/tests-conda.yml
+++ b/.github/workflows/tests-conda.yml
@@ -24,6 +24,12 @@ jobs:
       matrix:
         os: [ubuntu-latest, macos-latest, windows-2019]
         python: ["3.9", "3.10"]
+        env: ["environment.yml"]
+        include:
+          # minimal environment without optional dependencies
+          - os: "ubuntu-latest"
+            python: "3.10"
+            env: "environment-minimal.yml"
 
     steps:
       - name: Checkout repo
@@ -32,7 +38,7 @@ jobs:
       - name: Install Conda environment with Micromamba
         uses: mamba-org/provision-with-micromamba@main
         with:
-          environment-file: ci/environment.yml
+          environment-file: ci/${{ matrix.env }}
           extra-specs: python=${{ matrix.python }}
           cache-env: true
 
diff --git a/ci/environment-minimal.yml b/ci/environment-minimal.yml
new file mode 100644
index 00000000..a9e57496
--- /dev/null
+++ b/ci/environment-minimal.yml
@@ -0,0 +1,8 @@
+name: test
+channels:
+  - conda-forge
+dependencies:
+  - numpy
+  - libgdal
+  - pytest
+
diff --git a/pyogrio/tests/conftest.py b/pyogrio/tests/conftest.py
index 734cbb59..07027d3e 100644
--- a/pyogrio/tests/conftest.py
+++ b/pyogrio/tests/conftest.py
@@ -4,7 +4,7 @@
 import pytest
 
 from pyogrio import __gdal_version_string__, __version__, list_drivers
-import pyogrio
+from pyogrio.raw import read, write
 
 
 _data_dir = Path(__file__).parent.resolve() / "fixtures"
@@ -27,12 +27,16 @@ def prepare_testfile(testfile_path, dst_dir, ext):
     dst_path = dst_dir / f"{testfile_path.stem}{ext}"
     if dst_path.exists():
         return dst_path
-    gdf = pyogrio.read_dataframe(testfile_path)
+
+    meta, _, geometry, field_data = read(testfile_path)
+
     if ext == ".fgb":
         # For .fgb, spatial_index=False to avoid the rows being reordered
-        pyogrio.write_dataframe(gdf, dst_path, spatial_index=False)
-    else:
-        pyogrio.write_dataframe(gdf, dst_path)
+        meta["spatial_index"] = False
+        # allow mixed Polygons/MultiPolygons type
+        meta["geometry_type"] = "Unknown"
+
+    write(dst_path, geometry, field_data, **meta)
     return dst_path
 
 
diff --git a/pyogrio/tests/test_geopandas_io.py b/pyogrio/tests/test_geopandas_io.py
index 707870c9..9162e0d5 100644
--- a/pyogrio/tests/test_geopandas_io.py
+++ b/pyogrio/tests/test_geopandas_io.py
@@ -2,8 +2,6 @@
 import os
 
 import numpy as np
-import pandas as pd
-from pandas.testing import assert_frame_equal, assert_index_equal
 import pytest
 
 from pyogrio import list_layers, read_info, __gdal_geos_version__
@@ -13,6 +11,9 @@
 from pyogrio.tests.conftest import ALL_EXTS
 
 try:
+    import pandas as pd
+    from pandas.testing import assert_frame_equal, assert_index_equal
+
     import geopandas as gp
     from geopandas.testing import assert_geodataframe_equal