From df0620e3cbab32c524117039a4ee727687b44b31 Mon Sep 17 00:00:00 2001
From: Dani Bodor <d.bodor@esciencecenter.nl>
Date: Wed, 6 Dec 2023 17:48:14 +0100
Subject: [PATCH] create generic equivalence check

---
 eitprocessing/mixins/equality.py | 59 ++++++++++++++++++++++++++++++++
 1 file changed, 59 insertions(+)

diff --git a/eitprocessing/mixins/equality.py b/eitprocessing/mixins/equality.py
index 16fa9ace2..dee4ecc1e 100644
--- a/eitprocessing/mixins/equality.py
+++ b/eitprocessing/mixins/equality.py
@@ -1,8 +1,10 @@
+from __future__ import annotations
 from abc import ABC
 from abc import abstractmethod
 from dataclasses import astuple
 from dataclasses import is_dataclass
 import numpy as np
+from typing_extensions import Self
 
 
 class Equivalence(ABC):
@@ -28,3 +30,60 @@ def _array_safe_eq(a, b) -> bool:
             return object.__eq__(a, b)  # `a == b` could trigger an infinite loop
         except TypeError:
             return NotImplemented
+
+    @abstractmethod
+    def isequivalent(
+        self,
+        other: Self,
+        raise_: bool = False,
+        checks: dict[str, bool] = None,
+    ) -> bool:
+        """Test whether the data structure between two objects are equivalent.
+
+        Equivalence in this case means that objects are equal in all respects,
+        except for data content. Generally data loaded from the same source with
+        identical preprocessing will be equivalent.
+
+        Args:
+            other: object that will be compared to self.
+            raise_:
+                if False (default): return `False` if not equivalent;
+                if `True`: raise `EquivalenceError` if not equivalence.
+            checks: Dictionary of bools that will be checked. This dictionary can be
+                defined in each child class individually.
+                Defaults to None, meaning that only `type`s are compared.
+
+        Raises:
+            EquivalenceError: if `raise_ == True` and the objects are not equivalent.
+
+        Returns:
+            bool describing result of equivalence comparison.
+        """
+        # TODO: find out what correct way is to send extra argument to parent class without pissing off the linter
+        if not checks:
+            checks = {}
+
+        if self == other:
+            return True
+        try:
+            if type(self) is not type(other):
+                raise EquivalenceError(
+                    f"Classes don't match: {type(self)}, {type(other)}"
+                )
+            for msg, check in checks.items():
+                if not check:
+                    raise EquivalenceError(msg)
+        except EquivalenceError as e:
+            if raise_:
+                raise e
+            return False
+        return True
+
+
+class EquivalenceError(TypeError, ValueError):
+    """Raised if objects are not equivalent.
+
+    Equivalence in this case means that objects are equal in all respects,
+    except for data content. Generally data loaded from the same source with
+    identical preprocessing will be equivalent.
+    """