REFACTOR: either-like handling of screenshot failures

CHANGELOG.md

@@ -212,8 +212,6 @@ should we even refactor out them from Condition and move to Match only?
 
 ### TODO: rename all conditions inside match.py so match can be fully used instead be + have #530
 
-### TODO: consider implementing either_res_or just for demo... 
-
 ### Deprecated conditions
 
 - `be.present` in favor of `be.present_in_dom`

selene/common/fp.py

@@ -20,8 +20,7 @@
 # OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 # SOFTWARE.
 import functools
-import inspect
-from typing import TypeVar, Callable, Any, Tuple, Optional
+from typing_extensions import TypeVar, Callable, Any, Tuple, Optional
 
 # T = TypeVar('T', bound=Callable[..., Any])
 T = TypeVar('T')
@@ -63,6 +62,23 @@ def identity(it: T) -> T:
     return it
 
 
+# todo: what about decorator? like:
+#       > res, maybe_failure = _either(res=func, or_=Exception)(*args, **kwargs)
+#       over
+#       > res, maybe_failure = _either_res_or(Exception, func, *args, **kwargs)
+# todo: support exception_type as tuple of exception types
+# todo: make generic-aware version of this function,
+#       that knows the type of failure
+#       that knows the type of fn res
+def _either_res_or(
+    exception_type, fn: Callable, /, *args, **kwargs
+) -> Tuple[Any, Optional[Exception]]:
+    try:
+        return fn(*args, **kwargs), None
+    except exception_type as failure:
+        return ..., failure
+
+
 def pipe(*functions) -> Optional[Callable[[Any], Any]]:
     """
     pipes functions one by one in the provided order

selene/core/configuration.py

@@ -1427,30 +1427,21 @@ def _inject_screenshot_and_page_source_pre_hooks(self, hook):
         # TODO: consider moving hooks to class methods accepting config as argument
         #       or refactor somehow to eliminate all times defining hook fns
         def save_and_log_screenshot(error: TimeoutException) -> Exception:
-            path = None
-            failure_reason: WebDriverException | None = None
-            try:
-                # todo: consider changing _save_screenshot_strategy to be Either-like
-                # TODO: consider refactoring to be Either-monad-like
-                #       so we can eliminate try..except clauses
-                #       > path, maybe_failure = either_res_or(
-                #       >   WebDriverException
-                #       >   self._save_screenshot_strategy,
-                #       >   self,
-                #       > )
-                path = self._save_screenshot_strategy(self)  # type: ignore
-            except WebDriverException as reason:
-                failure_reason = reason
+            # todo: consider changing _save_screenshot_strategy to be Either-like
+            #       > path, maybe_failure = self._save_screenshot_strategy(self)
+            path, maybe_failure = fp._either_res_or(
+                WebDriverException, self._save_screenshot_strategy, self
+            )
             return TimeoutException(
                 error.msg
                 # todo: should we just skip logging screenshot at all when failure?
                 + '\nScreenshot: '
                 + (
                     self._format_path_as_uri(path)
-                    if path and not failure_reason
+                    if path and not maybe_failure
                     else 'cannot be saved because of: {name}: {message}'.format(
-                        name=failure_reason.__class__.__name__,
-                        message=getattr(failure_reason, "msg", str(failure_reason)),
+                        name=maybe_failure.__class__.__name__,
+                        message=getattr(maybe_failure, "msg", str(maybe_failure)),
                     )
                 )
             )
@@ -1464,23 +1455,18 @@ def save_and_log_page_source(error: TimeoutException) -> Exception:
                 else self._generate_filename(suffix='.html')
             )
 
-            path = None
-            failure_reason: WebDriverException | None = None
-            try:
-                # TODO: consider refactoring to be Either-monad-like
-                #       so we can eliminate try..except clauses
-                path = self._save_page_source_strategy(self, filename)
-            except WebDriverException as reason:
-                failure_reason = reason
+            path, maybe_failure = fp._either_res_or(
+                WebDriverException, self._save_screenshot_strategy, self
+            )
             return TimeoutException(
                 error.msg
                 + '\nPageSource: '
                 + (
                     self._format_path_as_uri(path)
-                    if path and not failure_reason
+                    if path and not maybe_failure
                     else 'cannot be saved because of: {name}: {message}'.format(
-                        name=failure_reason.__class__.__name__,
-                        message=getattr(failure_reason, "msg", str(failure_reason)),
+                        name=maybe_failure.__class__.__name__,
+                        message=getattr(maybe_failure, "msg", str(maybe_failure)),
                     )
                 )
             )