From b66defed25b13528d6c60050290528033ec01dad Mon Sep 17 00:00:00 2001
From: b3b <ash.b3b@gmail.com>
Date: Wed, 15 Dec 2021 21:18:31 +0300
Subject: [PATCH] add a prohibition to combine scan filters of the same type
 #25

---
 able/filters.py       | 12 ++++++++++++
 tests/test_filters.py |  8 ++++++++
 2 files changed, 20 insertions(+)

diff --git a/able/filters.py b/able/filters.py
index 6eeee94..383c23a 100644
--- a/able/filters.py
+++ b/able/filters.py
@@ -16,11 +16,23 @@
 
 @dataclass
 class Filter:
+    """Base class for BLE scanning fiters.
+
+    >>> # Filters of different kinds could be ANDed to set multiple conditions.
+    >>> # Both device name and address required:
+    >>> combined_filter = DeviceNameFilter("Example") & DeviceAddressFilter("01:02:03:AB:CD:EF")
+
+    >>> DeviceNameFilter("Example1") & DeviceNameFilter("Example2")
+    Traceback (most recent call last):
+    ValueError: cannot combine filters of the same type
+    """
 
     def __post_init__(self):
         self.filters = [self]
 
     def __and__(self, other):
+        if type(self) in (type(f) for f in other.filters):
+            raise ValueError('cannot combine filters of the same type')
         self.filters.extend(other.filters)
         return self
 
diff --git a/tests/test_filters.py b/tests/test_filters.py
index c027da8..bd2f446 100644
--- a/tests/test_filters.py
+++ b/tests/test_filters.py
@@ -40,3 +40,11 @@ def test_filters_combined(java_builder):
         ("setManufacturerData", ("test-id", [1, 2, 3])),
         ("build", )
     ]
+
+
+def test_combine_same_type_exception(java_builder):
+    with pytest.raises(ValueError, match="cannot combine filters of the same type"):
+        f = filters.DeviceNameFilter("test") & (
+            filters.DeviceAddressFilter("AA:AA:AA:AA:AA:AA") &
+            filters.DeviceNameFilter("test2")
+        )