Add example to and unit test.

tests/test_utils.py

@@ -0,0 +1,43 @@
+import inspect
+import sys
+
+from welleng.units import ureg
+from welleng.utils import annular_volume
+
+
+def test_annular_volume():
+    av = annular_volume(
+        od=ureg('12.25 inch').to('meter'),
+        id=ureg(f'{9+5/8} inch').to('meter'),
+        length=ureg('1000 meter')
+    )
+
+    assert av.m == 3.491531223156194
+    assert str(av.u) == 'meter ** 3'
+
+    pass
+
+
+def one_function_to_run_them_all():
+    """
+    Function to gather the test functions so that they can be tested by
+    running this module.
+
+    https://stackoverflow.com/questions/18907712/python-get-list-of-all-
+    functions-in-current-module-inspecting-current-module
+    """
+    test_functions = [
+        obj for name, obj in inspect.getmembers(sys.modules[__name__])
+        if (inspect.isfunction(obj)
+            and name.startswith('test')
+            and name != 'all')
+    ]
+
+    for f in test_functions:
+        f()
+
+        pass
+
+
+if __name__ == '__main__':
+    one_function_to_run_them_all()

welleng/survey.py

@@ -7,11 +7,7 @@
 except ImportError:
     MAG_CALC = False
 from datetime import datetime
-try:
-    from pyproj import CRS, Proj
-    GRID_CALC = True
-except ImportError:
-    GRID_CALC = False
+from pyproj import CRS, Proj
 from scipy.optimize import minimize
 from scipy.spatial.transform import Rotation as R
 
@@ -70,8 +66,6 @@ def __init__(self, projection: str = "EPSG:23031") -> None:
         ---------
         For codes refer to [EPSG](https://epsg.io).
         """
-        if not GRID_CALC:
-            raise ImportError('pyproj dependency required, try ``pip install pyproj``.')
         self.crs = CRS(projection)
         super().__init__(self.crs)
 

welleng/utils.py

@@ -664,6 +664,19 @@ def annular_volume(od: float, id: float = None, length: float = None):
     -------
     annular_volume: float
         The (unit) volume of the annulus or cylinder.
+
+    Example
+    -------
+    ```python
+    >>> from welleng.utils import annular_volume
+    >>> from welleng.units import ureg
+    >>> av = annular_volume(
+    ...     od=ureg('12.25 inch').to('meters),
+    ...     id=ureg(f'{9+5/8} inch').to('meter'),
+    ...     length=ureg('1000 meter')
+    ... )
+    >>> print(av)
+    ... 3.491531223156194 meter ** 3
     """
     length = 1 if length is None else length
     id = 0 if id is None else id