From 53726f702e6e40d0edf09fe132f338b6d79212dd Mon Sep 17 00:00:00 2001
From: Victor Engmark <victor@engmark.name>
Date: Sat, 19 Jun 2021 15:30:33 +1200
Subject: [PATCH 1/2] tests: Verify empty observation_direction property

---
 tests/extensions/test_sar.py | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/tests/extensions/test_sar.py b/tests/extensions/test_sar.py
index 23311bced..d2f939e04 100644
--- a/tests/extensions/test_sar.py
+++ b/tests/extensions/test_sar.py
@@ -1,9 +1,12 @@
 """Tests for pystac.extensions.sar."""
 
 import datetime
+from random import choice
 from typing import List
 import unittest
 
+from string import ascii_letters
+
 import pystac
 from pystac.extensions import sar
 from pystac.extensions.sar import SarExtension
@@ -180,6 +183,16 @@ def test_asset_ext_add_to(self) -> None:
 
         self.assertIn(SarExtension.get_schema_uri(), item.stac_extensions)
 
+    def test_should_return_none_when_observation_direction_is_not_set(self) -> None:
+        extension = SarExtension.ext(self.item)
+        extension.apply(
+            choice(ascii_letters),
+            choice(list(sar.FrequencyBand)),
+            [],
+            choice(ascii_letters),
+        )
+        self.assertIsNone(extension.observation_direction)
+
 
 if __name__ == "__main__":
     unittest.main()

From 431b5a74647222ea48da27e7dfb6f4f87cc3711d Mon Sep 17 00:00:00 2001
From: Victor Engmark <victor@engmark.name>
Date: Sat, 19 Jun 2021 15:41:39 +1200
Subject: [PATCH 2/2] feat: Print human readable type name in error messages

Based on <https://stackoverflow.com/a/13477954/96588>.

Also add tests to verify the exception being thrown.
---
 pystac/extensions/sar.py      |  2 +-
 pystac/extensions/view.py     |  2 +-
 tests/extensions/test_sar.py  | 11 +++++++++++
 tests/extensions/test_view.py | 12 ++++++++++++
 4 files changed, 25 insertions(+), 2 deletions(-)

diff --git a/pystac/extensions/sar.py b/pystac/extensions/sar.py
index 0f07213ea..9fd18ba28 100644
--- a/pystac/extensions/sar.py
+++ b/pystac/extensions/sar.py
@@ -318,7 +318,7 @@ def ext(cls, obj: T, add_if_missing: bool = False) -> "SarExtension[T]":
             return cast(SarExtension[T], AssetSarExtension(obj))
         else:
             raise pystac.ExtensionTypeError(
-                f"SAR extension does not apply to type {type(obj)}"
+                f"SAR extension does not apply to type '{type(obj).__name__}'"
             )
 
 
diff --git a/pystac/extensions/view.py b/pystac/extensions/view.py
index 6438a2cb0..47a6333d3 100644
--- a/pystac/extensions/view.py
+++ b/pystac/extensions/view.py
@@ -167,7 +167,7 @@ def ext(cls, obj: T, add_if_missing: bool = False) -> "ViewExtension[T]":
             return cast(ViewExtension[T], AssetViewExtension(obj))
         else:
             raise pystac.ExtensionTypeError(
-                f"View extension does not apply to type {type(obj)}"
+                f"View extension does not apply to type '{type(obj).__name__}'"
             )
 
     @staticmethod
diff --git a/tests/extensions/test_sar.py b/tests/extensions/test_sar.py
index d2f939e04..38ae253eb 100644
--- a/tests/extensions/test_sar.py
+++ b/tests/extensions/test_sar.py
@@ -8,6 +8,7 @@
 from string import ascii_letters
 
 import pystac
+from pystac import ExtensionTypeError
 from pystac.extensions import sar
 from pystac.extensions.sar import SarExtension
 from tests.utils import TestCases
@@ -193,6 +194,16 @@ def test_should_return_none_when_observation_direction_is_not_set(self) -> None:
         )
         self.assertIsNone(extension.observation_direction)
 
+    def test_should_raise_exception_when_passing_invalid_extension_object(
+        self,
+    ) -> None:
+        self.assertRaisesRegex(
+            ExtensionTypeError,
+            r"^SAR extension does not apply to type 'object'$",
+            SarExtension.ext,
+            object(),
+        )
+
 
 if __name__ == "__main__":
     unittest.main()
diff --git a/tests/extensions/test_view.py b/tests/extensions/test_view.py
index ac6f10a5d..c24ef8222 100644
--- a/tests/extensions/test_view.py
+++ b/tests/extensions/test_view.py
@@ -1,4 +1,6 @@
 import json
+
+from pystac import ExtensionTypeError
 from pystac.collection import Collection
 import unittest
 
@@ -257,6 +259,16 @@ def test_asset_ext_add_to(self) -> None:
 
         self.assertIn(ViewExtension.get_schema_uri(), item.stac_extensions)
 
+    def test_should_raise_exception_when_passing_invalid_extension_object(
+        self,
+    ) -> None:
+        self.assertRaisesRegex(
+            ExtensionTypeError,
+            r"^View extension does not apply to type 'object'$",
+            ViewExtension.ext,
+            object(),
+        )
+
 
 class ViewSummariestest(unittest.TestCase):
     def setUp(self) -> None: