Add a pytest setup

- setup pytest test folder and configs with just a dummy test for now

conftest.py

@@ -0,0 +1,30 @@
+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+"""Pytest configuration."""
+
+import pytest
+
+
+def pytest_addoption(parser):
+    """Adds --integration option to pytest."""
+    parser.addoption(
+        "--integration",
+        action="store_true",
+        default=False,
+        help="Run integration tests.",
+    )
+
+
+def pytest_configure(config):
+    """Adds marker for slow."""
+    config.addinivalue_line("markers", "integration: mark test as an integration test")
+
+
+def pytest_collection_modifyitems(config, items):
+    """Skips tests marked slow if --integration isn't used."""
+    if config.getoption("--integration"):
+        return
+    skip_integration = pytest.mark.skip(reason="need --integration option to run")
+    for item in items:
+        if "integration" in item.keywords:
+            item.add_marker(skip_integration)

tests/__init__.py

@@ -0,0 +1 @@
+"""Unit test package for fact-species-viz."""

tests/test_fact_species_viz.py

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+#!/usr/bin/env python
+
+"""Tests for `fact_species_viz` package."""
+
+import pytest
+
+
+@pytest.fixture
+def example_data() -> str:
+    return "hi"
+
+
+def test_content(example_data):
+    """Sample pytest test function with the pytest fixture as an argument."""
+    assert example_data == "hi"