Add convenience method for accessing pystac_client (#1365)

* Add convenience method for accessing pystac_client

* Write test that mocks missing import

* Ignore mypy

* Add to docs

* Update changelog

Author: jsignell

CHANGELOG.md

@@ -5,6 +5,7 @@
 ### Added
 
 - Add netCDF to pystac.media_type ([#1386](https://github.com/stac-utils/pystac/pull/1386)) 
+- Add convenience method for accessing pystac_client ([#1365](https://github.com/stac-utils/pystac/pull/1365))
 
 ### Changed
 

docs/api.rst

@@ -86,6 +86,18 @@ as to serialize and deserialize STAC object to and from JSON.
 * :class:`pystac.stac_io.DefaultStacIO`: The default :class:`pystac.StacIO`
   implementation used throughout the library.
 
+Client
+------
+
+A convenience method for accessing `pystac-client <https://github.com/stac-utils/pystac-client>`__
+
+**Example:**
+
+.. code-block:: python
+
+  from pystac.client import Client
+
+
 Extensions
 ----------
 

pystac/client.py

@@ -0,0 +1,23 @@
+# mypy: ignore-errors
+
+_import_error_message = (
+    "pystac-client is not installed.\n\n"
+    "Please install pystac-client:\n\n"
+    "  pip install pystac-client"
+)
+
+try:
+    from pystac_client import *  # noqa: F403
+except ImportError as e:
+    if e.msg == "No module named 'pystac_client'":
+        raise ImportError(_import_error_message) from e
+    else:
+        raise
+
+
+def __getattr__(value: str):
+    try:
+        import pystac_client
+    except ImportError as e:
+        raise ImportError(_import_error_message) from e
+    return getattr(pystac_client, value)

tests/test_pystac_client.py

@@ -0,0 +1,43 @@
+# mypy: ignore-errors
+import builtins
+import sys
+from types import ModuleType
+from typing import Any
+
+import pytest
+
+real_import = builtins.__import__
+
+try:
+    import pystac_client  # noqa:F401
+
+    HAS_PYSTAC_CLIENT = True
+except ImportError:
+    HAS_PYSTAC_CLIENT = False
+
+
+@pytest.mark.skipif(not HAS_PYSTAC_CLIENT, reason="requires pystac_client")
+def test_import_pystac_client_when_available() -> None:
+    from pystac.client import Client
+
+    assert Client.__doc__
+
+
+# copied from
+# http://materials-scientist.com/blog/2021/02/11/mocking-failing-module-import-python/
+def monkey_import_importerror(name: str, *args: Any, **kwargs: Any) -> ModuleType:
+    if name == "pystac_client":
+        raise ImportError(f"No module named '{name}'")
+    return real_import(name, *args, **kwargs)
+
+
+def test_import_pystac_client_when_not_available(monkeypatch: Any) -> None:
+    if HAS_PYSTAC_CLIENT:
+        monkeypatch.delitem(sys.modules, "pystac_client", raising=False)
+        monkeypatch.setattr(builtins, "__import__", monkey_import_importerror)
+
+    with pytest.raises(ImportError):
+        from pystac_client import Client  # noqa:F401
+
+    with pytest.raises(ImportError, match="Please install pystac-client:"):
+        from pystac.client import Client  # noqa:F401,F811