test: add unit tests for SetSharpJsonReader

Add comprehensive test cases for SetSharpJsonReader to verify correct behavior when reading values from JSON dictionaries. Tests cover various scenarios including top-level and nested paths, non-existent keys, null inputs, and invalid paths.

Author: Amirhossein Beheshti

tests/SetSharp.Tests/Helpers/SetSharpJsonReaderTests.cs

@@ -0,0 +1,147 @@
+using SetSharp.Helpers;
+
+namespace SetSharp.Tests.Helpers
+{
+    public class SetSharpJsonReaderTests
+    {
+        private readonly Dictionary<string, object> _testJson = new()
+        {
+            { "TopLevelString", "Hello World" },
+            { "TopLevelInt", 123 },
+            { "SetSharp", new Dictionary<string, object>
+                {
+                    { "Enabled", true },
+                    { "Generation", new Dictionary<string, object>
+                        {
+                            { "Poco", true },
+                            { "OptionsPattern", false }
+                        }
+                    }
+                }
+            }
+        };
+
+        [Fact]
+        public void Read_WithValidTopLevelPath_ReturnsCorrectValue()
+        {
+            // Arrange
+            var keyPath = "TopLevelString";
+
+            // Act
+            var result = SetSharpJsonReader.Read(_testJson, keyPath);
+
+            // Assert
+            Assert.Equal("Hello World", result);
+        }
+
+        [Fact]
+        public void Read_WithValidNestedPath_ReturnsCorrectValue()
+        {
+            // Arrange
+            var keyPath = "SetSharp:Enabled";
+
+            // Act
+            var result = SetSharpJsonReader.Read(_testJson, keyPath);
+
+            // Assert
+            Assert.IsType<bool>(result);
+            Assert.Equal(true, result);
+        }
+
+        [Fact]
+        public void Read_WithDeeplyNestedPath_ReturnsCorrectValue()
+        {
+            // Arrange
+            var keyPath = "SetSharp:Generation:Poco";
+
+            // Act
+            var result = SetSharpJsonReader.Read(_testJson, keyPath);
+
+            // Assert
+            Assert.IsType<bool>(result);
+            Assert.Equal(true, result);
+        }
+
+        [Fact]
+        public void Read_PathToADictionary_ReturnsDictionaryObject()
+        {
+            // Arrange
+            var keyPath = "SetSharp:Generation";
+
+            // Act
+            var result = SetSharpJsonReader.Read(_testJson, keyPath);
+
+            // Assert
+            var dictResult = Assert.IsType<Dictionary<string, object>>(result);
+            Assert.True((bool)dictResult["Poco"]);
+            Assert.False((bool)dictResult["OptionsPattern"]);
+        }
+
+        [Fact]
+        public void Read_WithNonExistentTopLevelKey_ReturnsNull()
+        {
+            // Arrange
+            var keyPath = "NonExistent";
+
+            // Act
+            var result = SetSharpJsonReader.Read(_testJson, keyPath);
+
+            // Assert
+            Assert.Null(result);
+        }
+
+        [Fact]
+        public void Read_WithNonExistentNestedKey_ReturnsNull()
+        {
+            // Arrange
+            var keyPath = "SetSharp:Generation:NonExistent";
+
+            // Act
+            var result = SetSharpJsonReader.Read(_testJson, keyPath);
+
+            // Assert
+            Assert.Null(result);
+        }
+
+        [Fact]
+        public void Read_PathGoesThroughLeafValue_ReturnsNull()
+        {
+            // Arrange
+            // Trying to navigate deeper into "TopLevelString", which is not a dictionary
+            var keyPath = "TopLevelString:Deeper";
+
+            // Act
+            var result = SetSharpJsonReader.Read(_testJson, keyPath);
+
+            // Assert
+            Assert.Null(result);
+        }
+
+        [Fact]
+        public void Read_WithNullJson_ReturnsNull()
+        {
+            // Arrange
+            Dictionary<string, object> nullJson = null;
+            var keyPath = "Any:Path";
+
+            // Act
+            var result = SetSharpJsonReader.Read(nullJson, keyPath);
+
+            // Assert
+            Assert.Null(result);
+        }
+
+        [Theory]
+        [InlineData(null)]
+        [InlineData("")]
+        [InlineData(" ")]
+        public void Read_WithInvalidKeyPath_ReturnsNull(string invalidKeyPath)
+        {
+            // Act
+            var result = SetSharpJsonReader.Read(_testJson, invalidKeyPath);
+
+            // Assert
+            Assert.Null(result);
+        }
+    }
+}