Align Context to a read-only dict interface

fmf/context.py

@@ -17,6 +17,8 @@
 """
 
 import re
+from collections.abc import Mapping
+from typing import Union
 
 
 class CannotDecide(Exception):
@@ -215,7 +217,7 @@ def __hash__(self):
         return hash(self._to_compare)
 
 
-class Context:
+class Context(Mapping[str, set[ContextValue]]):
     """
     Represents https://fmf.readthedocs.io/en/latest/context.html
     """
@@ -455,7 +457,9 @@ def _op_core(self, dimension_name, values, comparator):
     # To split by 'or' operator
     re_or_split = re.compile(r'\bor\b')
 
-    def __init__(self, *args, **kwargs):
+    _dimensions: dict[str, set[ContextValue]]
+
+    def __init__(self, **kwargs: Union[str, list[str]]) -> None:
         """
         Context(rule string)
         Context(dimension=ContextValue())
@@ -466,26 +470,22 @@ def __init__(self, *args, **kwargs):
         self._dimensions = {}
         self.case_sensitive = True
 
-        # Initialized with rule
-        if args:
-            if len(args) != 1:
-                raise InvalidContext()
-            definition = Context.parse_rule(args[0])
-            # No ORs and at least one expression in AND
-            if len(definition) != 1 or not definition[0]:
-                raise InvalidContext()
-            for dim, op, values in definition[0]:
-                if op != "==":
-                    raise InvalidContext()
-                self._dimensions[dim] = set(values)
-        # Initialized with dimension=value(s)
         for dimension_name, values in kwargs.items():
             if not isinstance(values, list):
                 values = [values]
             self._dimensions[dimension_name] = set(
                 [self.parse_value(val) for val in values]
                 )
 
+    def __getitem__(self, key: str) -> set[ContextValue]:
+        return self._dimensions[key]
+
+    def __len__(self):
+        return len(self._dimensions)
+
+    def __iter__(self):
+        yield from self._dimensions
+
     @property
     def case_sensitive(self) -> bool:
         return self._case_sensitive

tests/unit/test_context.py

@@ -1,7 +1,6 @@
 import pytest
 
-from fmf.context import (CannotDecide, Context, ContextValue, InvalidContext,
-                         InvalidRule)
+from fmf.context import CannotDecide, Context, ContextValue, InvalidRule
 
 
 @pytest.fixture
@@ -246,7 +245,7 @@ def test_module_streams(self):
         How you can use Context for modules
         """
 
-        perl = Context("module = perl:5.28")
+        perl = Context(module="perl:5.28")
 
         assert perl.matches("module >= perl:5")
         assert not perl.matches("module > perl:5")
@@ -262,7 +261,7 @@ def test_module_streams(self):
         # e.g feature in 5.28+ but dropped in perl6
         assert perl.matches("module ~>= perl:5.28")
         with pytest.raises(CannotDecide):
-            Context("module = perl:6.28").matches("module ~>= perl:5.28")
+            Context(module="perl:6.28").matches("module ~>= perl:5.28")
 
     def test_comma(self):
         """
@@ -613,20 +612,10 @@ def test_parse_rule(self):
 
 class TestContext:
     def test_creation(self):
-        for created in [
-                Context(dim_a="value", dim_b=["val"], dim_c=["foo", "bar"]),
-                Context("dim_a=value and dim_b=val and dim_c == foo,bar")]:
-            assert created._dimensions["dim_a"] == set([ContextValue("value")])
-            assert created._dimensions["dim_b"] == set([ContextValue("val")])
-            assert created._dimensions["dim_c"] == set(
-                [ContextValue("foo"), ContextValue("bar")])
-        # Invalid ways to create Context
-        with pytest.raises(InvalidContext):
-            Context("a=b", "c=d")  # Just argument
-        with pytest.raises(InvalidContext):
-            Context("a=b or c=d")  # Can't use OR
-        with pytest.raises(InvalidContext):
-            Context("a < d")  # Operator other than =/==
+        context = Context(dim_a="value", dim_b=["val"], dim_c=["foo", "bar"])
+        assert context._dimensions["dim_a"] == {ContextValue("value")}
+        assert context._dimensions["dim_b"] == {ContextValue("val")}
+        assert context._dimensions["dim_c"] == {ContextValue("foo"), ContextValue("bar")}
 
     def test_prints(self):
         c = Context()
@@ -811,18 +800,18 @@ def test_known_troublemakers(self):
 
         assert Context(distro='fedora-33').matches('distro == fedora')
         with pytest.raises(CannotDecide):
-            Context("module = py:5.28").matches("module > perl:5.28")
+            Context(module="py:5.28").matches("module > perl:5.28")
         with pytest.raises(CannotDecide):
-            Context("module = py:5").matches("module > perl:5.28")
+            Context(module="py:5").matches("module > perl:5.28")
         with pytest.raises(CannotDecide):
-            Context("module = py:5").matches("module >= perl:5.28")
+            Context(module="py:5").matches("module >= perl:5.28")
         with pytest.raises(CannotDecide):
-            Context("distro = centos").matches("distro >= fedora")
+            Context(distro="centos").matches("distro >= fedora")
 
-        assert Context("distro = centos").matches("distro != fedora")
-        assert not Context("distro = centos").matches("distro == fedora")
+        assert Context(distro="centos").matches("distro != fedora")
+        assert not Context(distro="centos").matches("distro == fedora")
 
-        rhel7 = Context("distro = rhel-7")
+        rhel7 = Context(distro="rhel-7")
         assert rhel7.matches("distro == rhel")
         assert rhel7.matches("distro == rhel-7")
         assert not rhel7.matches("distro == rhel-7.3")