Add versioning scripts and update README for packaging instructions

tests/test_release_scripts.py

@@ -0,0 +1,55 @@
+from __future__ import annotations
+
+import sys
+import tomllib
+from pathlib import Path
+
+
+ROOT = Path(__file__).resolve().parent.parent
+sys.path.insert(0, str(ROOT / "scripts"))
+
+from set_version import extract_project_version, set_project_version_in_text, write_project_version
+
+
+def test_extract_project_version_reads_project_version() -> None:
+    pyproject_text = (
+        "[build-system]\n"
+        'requires = ["setuptools>=69", "wheel"]\n\n'
+        "[project]\n"
+        'name = "ebay-rest-client"\n'
+        'version = "0.1.0"\n'
+    )
+
+    assert extract_project_version(pyproject_text) == "0.1.0"
+
+
+def test_set_project_version_in_text_updates_project_version_only() -> None:
+    pyproject_text = (
+        "[build-system]\n"
+        'requires = ["setuptools>=69", "wheel"]\n\n'
+        "[project]\n"
+        'name = "ebay-rest-client"\n'
+        'version = "0.1.0"\n'
+        'description = "test package"\n'
+    )
+
+    updated_text = set_project_version_in_text(pyproject_text, "1.2.3")
+
+    assert extract_project_version(updated_text) == "1.2.3"
+    assert tomllib.loads(updated_text)["project"]["version"] == "1.2.3"
+
+
+def test_write_project_version_updates_file(tmp_path: Path) -> None:
+    pyproject_path = tmp_path / "pyproject.toml"
+    pyproject_path.write_text(
+        "[project]\n"
+        'name = "ebay-rest-client"\n'
+        'version = "0.1.0"\n',
+        encoding="utf-8",
+    )
+
+    previous_version, updated_version = write_project_version(pyproject_path, "2.0.0")
+
+    assert previous_version == "0.1.0"
+    assert updated_version == "2.0.0"
+    assert tomllib.loads(pyproject_path.read_text(encoding="utf-8"))["project"]["version"] == "2.0.0"