Added Tests. Added Contains method

FlexArray.Test/FlexArrayStringTests.cs

@@ -83,4 +83,51 @@ public class FlexArrayStringTests
         array.Capacity.Should().BeGreaterThan(FlexArrayString.DefaultStartSize, "capacity exceeded, had to grow"); 
         array.Count.Should().Be(FlexArrayString.DefaultStartSize + 2);
     }
+    
+    // Contains tests
+    [Fact]
+    public void Contains_Success()
+    {
+        var array = new FlexArrayString();
+        array.Add("Goodbye");
+        array.Add("World");
+        array.Add("!");
+        array.Add("bye...");
+
+        array.Contains("!")
+             .Should().BeTrue();
+    }
+
+    [Fact]
+    public void Contains_Success_AfterGrowth()
+    {
+        var array = new FlexArrayString();
+        for (var i = 0; i <= FlexArrayString.DefaultStartSize; i++)
+        {
+            array.Add(i.ToString());
+        }
+
+        array.Contains(array[FlexArrayString.DefaultStartSize - 1])
+             .Should().BeTrue();
+    }
+
+    [Fact]
+    public void Contains_Empty()
+    {
+        var array = new FlexArrayString();
+
+        array.Contains("Hi!")
+             .Should().BeFalse("collection is empty");
+    }
+
+    [Fact]
+    public void Contains_NotFound()
+    {
+        var array = new FlexArrayString();
+        array.Add("Hello");
+        array.Add("World");
+
+        array.Contains("!")
+             .Should().BeFalse("not contained in list");
+    }
 }

FlexArray/FlexArrayString.cs

@@ -28,14 +28,32 @@ public class FlexArrayString
         _data = new string[size];
     }
 
-    public void Add(string input)
+    public void Add(string value)
     {
         if (Capacity == Count)
         {
             Grow();
         }
 
-        _data[Count++] = input;
+        _data[Count++] = value;
+    }
+    
+    public bool Contains(string value)
+    {
+        if (Count == 0)
+        {
+            return false;
+        }
+
+        for (var i = 0; i < Count; i++)
+        {
+            if (_data[i] == value)
+            {
+                return true;
+            }
+        }
+
+        return false;
     }
 
     private void Grow()