feat: add custom jsonLogic string evaluators (#158)

Signed-off-by: Florian Bacher <[email protected]>
Co-authored-by: Todd Baert <[email protected]>

Author: bacherfl

Diff for: src/OpenFeature.Contrib.Providers.Flagd/Resolver/InProcess/CustomEvaluators/StringEvaluator.cs

@@ -0,0 +1,19 @@
+using System;
+using JsonLogic.Net;
+using Newtonsoft.Json.Linq;
+
+namespace OpenFeature.Contrib.Providers.Flagd.Resolver.InProcess.CustomEvaluators
+{
+    internal class StringEvaluator
+    {
+        internal object StartsWith(IProcessJsonLogic p, JToken[] args, object data)
+        {
+            return p.Apply(args[0], data).ToString().StartsWith(p.Apply(args[1], data).ToString());
+        }
+
+        internal object EndsWith(IProcessJsonLogic p, JToken[] args, object data)
+        {
+            return p.Apply(args[0], data).ToString().EndsWith(p.Apply(args[1], data).ToString());
+        }
+    }
+}

Diff for: src/OpenFeature.Contrib.Providers.Flagd/Resolver/InProcess/JsonEvaluator.cs

@@ -7,6 +7,7 @@
 using Newtonsoft.Json;
 using Newtonsoft.Json.Linq;
 using OpenFeature.Constant;
+using OpenFeature.Contrib.Providers.Flagd.Resolver.InProcess.CustomEvaluators;
 using OpenFeature.Error;
 using OpenFeature.Model;
 
@@ -58,6 +59,11 @@ internal class JsonEvaluator
         internal JsonEvaluator(string selector)
         {
             _selector = selector;
+
+            var stringEvaluator = new StringEvaluator();
+
+            EvaluateOperators.Default.AddOperator("starts_with", stringEvaluator.StartsWith);
+            EvaluateOperators.Default.AddOperator("ends_with", stringEvaluator.EndsWith);
         }
 
         internal void Sync(FlagConfigurationUpdateType updateType, string flagConfigurations)

Diff for: test/OpenFeature.Contrib.Providers.Flagd.Test/StringEvaluatorTest.cs

@@ -0,0 +1,132 @@
+using System.Collections.Generic;
+using JsonLogic.Net;
+using Newtonsoft.Json.Linq;
+using OpenFeature.Contrib.Providers.Flagd.Resolver.InProcess.CustomEvaluators;
+using Xunit;
+
+namespace OpenFeature.Contrib.Providers.Flagd.Test
+{
+    public class StringEvaluatorTest
+    {
+
+        [Fact]
+        public void StartsWith()
+        {
+            // Arrange
+            var evaluator = new JsonLogicEvaluator(EvaluateOperators.Default);
+            var stringEvaluator = new StringEvaluator();
+            EvaluateOperators.Default.AddOperator("starts_with", stringEvaluator.StartsWith);
+
+            var targetingString = @"{""starts_with"": [
+              {
+                ""var"": [
+                  ""color""
+                ]
+              },
+              ""yellow""
+            ]}";
+
+            // Parse json into hierarchical structure
+            var rule = JObject.Parse(targetingString);
+
+            var data = new Dictionary<string, string> { { "color", "yellowcolor" } };
+
+            // Act & Assert
+            var result = evaluator.Apply(rule, data);
+            Assert.True(result.IsTruthy());
+
+            data.Clear();
+            data.Add("color", "blue");
+
+            result = evaluator.Apply(rule, data);
+            Assert.False(result.IsTruthy());
+        }
+
+        [Fact]
+        public void EndsWith()
+        {
+            // Arrange
+            var evaluator = new JsonLogicEvaluator(EvaluateOperators.Default);
+            var stringEvaluator = new StringEvaluator();
+            EvaluateOperators.Default.AddOperator("ends_with", stringEvaluator.EndsWith);
+
+            var targetingString = @"{""ends_with"": [
+                        {
+                          ""var"": [
+                            ""color""
+                          ]
+                        },
+                        ""purple""
+                      ]}";
+
+            // Parse json into hierarchical structure
+            var rule = JObject.Parse(targetingString);
+
+            var data = new Dictionary<string, string> { { "color", "deep-purple" } };
+
+            // Act & Assert
+            var result = evaluator.Apply(rule, data);
+            Assert.True(result.IsTruthy());
+
+            data.Clear();
+            data.Add("color", "purple-nightmare");
+
+            result = evaluator.Apply(rule, data);
+            Assert.False(result.IsTruthy());
+        }
+
+        [Fact]
+        public void NonStringTypeInRule()
+        {
+            // Arrange
+            var evaluator = new JsonLogicEvaluator(EvaluateOperators.Default);
+            var stringEvaluator = new StringEvaluator();
+            EvaluateOperators.Default.AddOperator("ends_with", stringEvaluator.EndsWith);
+
+            var targetingString = @"{""ends_with"": [
+                        {
+                          ""var"": [
+                            ""color""
+                          ]
+                        },
+                        1
+                      ]}";
+
+            // Parse json into hierarchical structure
+            var rule = JObject.Parse(targetingString);
+
+            var data = new Dictionary<string, string> { { "color", "deep-purple" } };
+
+            // Act & Assert
+            var result = evaluator.Apply(rule, data);
+            Assert.False(result.IsTruthy());
+        }
+
+        [Fact]
+        public void NonStringTypeInData()
+        {
+            // Arrange
+            var evaluator = new JsonLogicEvaluator(EvaluateOperators.Default);
+            var stringEvaluator = new StringEvaluator();
+            EvaluateOperators.Default.AddOperator("ends_with", stringEvaluator.EndsWith);
+
+            var targetingString = @"{""ends_with"": [
+                        {
+                          ""var"": [
+                            ""color""
+                          ]
+                        },
+                        ""green""
+                      ]}";
+
+            // Parse json into hierarchical structure
+            var rule = JObject.Parse(targetingString);
+
+            var data = new Dictionary<string, int> { { "color", 5 } };
+
+            // Act & Assert
+            var result = evaluator.Apply(rule, data);
+            Assert.False(result.IsTruthy());
+        }
+    }
+}