Chore: Evaluation Context must only contain unique values

open-feature/spec#120

Signed-off-by: Benjamin Evenson <[email protected]>

Author: benjiro

test/OpenFeature.Tests/OpenFeatureEvaluationContextTests.cs

@@ -27,6 +27,7 @@ public void Should_Merge_Two_Contexts()
         }
 
         [Fact]
+        [Specification("3.2.2", "Duplicate values being overwritten.")]
         public void Should_Merge_TwoContexts_And_Override_Duplicates_With_RightHand_Context()
         {
             var context1 = new EvaluationContext();
@@ -77,5 +78,15 @@ public void EvaluationContext_Should_All_Types()
             context.Get<DateTime>("key4").Should().Be(now);
             context.Get<TestStructure>("key5").Should().Be(structure);
         }
+
+        [Fact]
+        [Specification("3.1.4", "The evaluation context fields MUST have an unique key.")]
+        public void When_Duplicate_Key_Throw_Unique_Constraint()
+        {
+            var context = new EvaluationContext { { "key", "value" } };
+            var exception = Assert.Throws<ArgumentException>(() =>
+                context.Add("key", "overriden_value"));
+            exception.Message.Should().Be("An item with the same key has already been added. Key: key");
+        }
     }
 }