ENH: fix raising exceptions with confusing tracebacks (#122)

* fix raising exceptions with confusing tracebacks

Plus:
- removing some pragmas (why?)

* typo in code - str not documented as valid input data

* Fix tests for improved error message

* Pytest: im too bad at reading xd

* dang it, im too tired

* pragma: no cover - i see what you did there. sry for the emails

* Adam's code review

Co-Authored-By: Adam R. Jensen <39184289+AdamRJensen@users.noreply.github.com>

---------

Co-authored-by: Adam R. Jensen <39184289+AdamRJensen@users.noreply.github.com>

Author: echedey-ls

src/solposx/solarposition/psa.py

@@ -1,3 +1,5 @@
+from collections.abc import Iterable
+
 import numpy as np
 import pandas as pd
 
@@ -72,13 +74,21 @@ def psa(times, latitude, longitude, *, coefficients=2020):
        :doi:`10.1016/j.solener.2020.10.084`
     """
 
-    if isinstance(coefficients, (int, str)):
+    if isinstance(coefficients, int):
         try:
             p = _PSA_PARAMS[coefficients]
         except KeyError:
-            raise ValueError(f"unknown coefficients set: {coefficients}")
-    else:
+            raise ValueError(
+                f"Unknown coefficients set: {coefficients}. "
+                f"Available options are: {_PSA_PARAMS.keys()}."
+            ) from None
+    elif isinstance(coefficients, Iterable) and len(coefficients) == 15:
         p = coefficients
+    else:
+        raise ValueError(
+            f"Coefficients must be one of: {_PSA_PARAMS.keys()}, "
+            "or a list of 15 coefficients."
+        )
 
     phi = np.radians(latitude)
     lambda_t = longitude

src/solposx/solarposition/sg2.py

@@ -287,8 +287,8 @@ def sg2_c(times, latitude, longitude, elevation=0, *, pressure=101325,
     except ImportError:  # pragma: no cover
         # Raise an error if package is not available
         raise ImportError(
-            'The sg2_c function requires the sg2 Python package.'
-            )  # pragma: no cover
+            "The sg2_c function requires the sg2 Python package."
+        ) from None
 
     # list of geopoints as 2D array of (N,3) where each row is repectively
     # longitude in degrees, latitude in degrees and altitude in meters.

src/solposx/solarposition/skyfield.py

@@ -49,8 +49,8 @@ def skyfield(times, latitude, longitude, *, de='de440.bsp'):
     except ImportError:  # pragma: no cover
         # Raise an error if package is not available
         raise ImportError(
-            'The skyfield function requires the skyfield Python package.'
-            )  # pragma: no cover
+            "The skyfield function requires the skyfield Python package."
+        ) from None
 
     if isinstance(de, str):
         de = load(de)

src/solposx/tools.py

@@ -24,9 +24,11 @@ def _pandas_to_utc(pd_object):
     try:
         pd_object_utc = pd_object.tz_convert('UTC')
     except TypeError:
-        raise TypeError('The provided time stamps are timezone naive.'
-                        'Please make the time stamps timezone aware.'
-                        'See ``pandas.Timestamp.tz_localize``.')
+        raise TypeError(
+            "The provided time stamps are timezone naive."
+            "Please make the time stamps timezone aware."
+            "See ``pandas.Timestamp.tz_localize``."
+        ) from None
     return pd_object_utc
 
 

tests/test_solarposition.py

@@ -495,13 +495,13 @@ def test_michalsky_julian_date_value_error():
 
 
 def test_psa_coefficients_value_error():
-    with pytest.raises(ValueError, match='unknown coefficients set: 1999'):
+    with pytest.raises(ValueError, match='Unknown coefficients set: 1999'):
         _ = psa(
             times=pd.date_range('2020-01-01', '2020-01-02', tz='UTC'),
             latitude=50, longitude=10,
             coefficients=1999,  # not a correct option
         )
-    with pytest.raises(ValueError, match='unknown coefficients set'):
+    with pytest.raises(ValueError, match='Coefficients must be one of'):
         _ = psa(
             times=pd.date_range('2020-01-01', '2020-01-02', tz='UTC'),
             latitude=50, longitude=10,