1 files changed, 131 insertions, 0 deletions
diff --git a/tests/test_filter.py b/tests/test_filter.py
new file mode 100644
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+++ b/tests/test_filter.py
@@ -0,0 +1,131 @@
+from __future__ import annotations
+
+import pytest
+
+from prompt_toolkit.filters import Always, Condition, Filter, Never, to_filter
+from prompt_toolkit.filters.base import _AndList, _OrList
+
+
+def test_never():
+    assert not Never()()
+
+
+def test_always():
+    assert Always()()
+
+
+def test_invert():
+    assert not (~Always())()
+    assert ~Never()()
+
+    c = ~Condition(lambda: False)
+    assert c()
+
+
+def test_or():
+    for a in (True, False):
+        for b in (True, False):
+            c1 = Condition(lambda: a)
+            c2 = Condition(lambda: b)
+            c3 = c1 | c2
+
+            assert isinstance(c3, Filter)
+            assert c3() == a or b
+
+
+def test_and():
+    for a in (True, False):
+        for b in (True, False):
+            c1 = Condition(lambda: a)
+            c2 = Condition(lambda: b)
+            c3 = c1 & c2
+
+            assert isinstance(c3, Filter)
+            assert c3() == (a and b)
+
+
+def test_nested_and():
+    for a in (True, False):
+        for b in (True, False):
+            for c in (True, False):
+                c1 = Condition(lambda: a)
+                c2 = Condition(lambda: b)
+                c3 = Condition(lambda: c)
+                c4 = (c1 & c2) & c3
+
+                assert isinstance(c4, Filter)
+                assert c4() == (a and b and c)
+
+
+def test_nested_or():
+    for a in (True, False):
+        for b in (True, False):
+            for c in (True, False):
+                c1 = Condition(lambda: a)
+                c2 = Condition(lambda: b)
+                c3 = Condition(lambda: c)
+                c4 = (c1 | c2) | c3
+
+                assert isinstance(c4, Filter)
+                assert c4() == (a or b or c)
+
+
+def test_to_filter():
+    f1 = to_filter(True)
+    f2 = to_filter(False)
+    f3 = to_filter(Condition(lambda: True))
+    f4 = to_filter(Condition(lambda: False))
+
+    assert isinstance(f1, Filter)
+    assert isinstance(f2, Filter)
+    assert isinstance(f3, Filter)
+    assert isinstance(f4, Filter)
+    assert f1()
+    assert not f2()
+    assert f3()
+    assert not f4()
+
+    with pytest.raises(TypeError):
+        to_filter(4)
+
+
+def test_filter_cache_regression_1():
+    # See: https://github.com/prompt-toolkit/python-prompt-toolkit/issues/1729
+
+    cond = Condition(lambda: True)
+
+    # The use of a `WeakValueDictionary` caused this following expression to
+    # fail. The problem is that the nested `(a & a)` expression gets garbage
+    # collected between the two statements and is removed from our cache.
+    x = (cond & cond) & cond
+    y = (cond & cond) & cond
+    assert x == y
+
+
+def test_filter_cache_regression_2():
+    cond1 = Condition(lambda: True)
+    cond2 = Condition(lambda: True)
+    cond3 = Condition(lambda: True)
+
+    x = (cond1 & cond2) & cond3
+    y = (cond1 & cond2) & cond3
+    assert x == y
+
+
+def test_filter_remove_duplicates():
+    cond1 = Condition(lambda: True)
+    cond2 = Condition(lambda: True)
+
+    # When a condition is appended to itself using an `&` or `|` operator, it
+    # should not be present twice. Having it twice in the `_AndList` or
+    # `_OrList` will make them more expensive to evaluate.
+
+    assert isinstance(cond1 & cond1, Condition)
+    assert isinstance(cond1 & cond1 & cond1, Condition)
+    assert isinstance(cond1 & cond1 & cond2, _AndList)
+    assert len((cond1 & cond1 & cond2).filters) == 2
+
+    assert isinstance(cond1 | cond1, Condition)
+    assert isinstance(cond1 | cond1 | cond1, Condition)
+    assert isinstance(cond1 | cond1 | cond2, _OrList)
+    assert len((cond1 | cond1 | cond2).filters) == 2