diff --git a/src/Models/ModelTag.cs b/src/Models/ModelTag.cs
index 77995ba..8eb7204 100644
--- a/src/Models/ModelTag.cs
+++ b/src/Models/ModelTag.cs
@@ -31,5 +31,5 @@ public void Deconstruct(out string name, out string sqlStatement)
     /// </summary>
     /// <returns>A string that represents the current object of type <see cref="ModelTag" />.</returns>
     public override string ToString()
-        => $"-- name: {Name}\n{SqlStatement}\n";
+        => $"-- name: {Name}{Environment.NewLine}{SqlStatement}{Environment.NewLine}";
 }
diff --git a/tests/YeSqlDictionaryTests.cs b/tests/YeSqlDictionaryTests.cs
new file mode 100644
index 0000000..d446f2f
--- /dev/null
+++ b/tests/YeSqlDictionaryTests.cs
@@ -0,0 +1,170 @@
+namespace YeSql.Net.Tests;
+
+public class YeSqlDictionaryTests
+{
+    [Test]
+    public void Indexer_WhenTagNameIsNull_ShouldThrowArgumentNullException()
+    {
+        // Arrange
+        var sqlCollection = new YeSqlDictionary();
+        var tagName = default(string);
+
+        // Act
+        Action action = () =>
+        {
+            var value = sqlCollection[tagName];
+        };
+
+        // Assert
+        action.Should()
+              .Throw<ArgumentNullException>()
+              .WithParameterName(nameof(tagName));
+    }
+
+    [Test]
+    public void Indexer_WhenTagNameIsNotFound_ShouldThrowTagNotFoundException()
+    {
+        // Arrange
+        var sqlCollection = new YeSqlDictionary();
+        var tagName = "Test";
+        var expectedMessage = string.Format(ExceptionMessages.TagNotFound, tagName);
+
+        // Act
+        Action action = () =>
+        {
+            var value = sqlCollection[tagName];
+        };
+
+        // Assert
+        action.Should()
+              .Throw<TagNotFoundException>()
+              .WithMessage(expectedMessage);
+    }
+
+    [Test]
+    public void Indexer_WhenTagNameIsFound_ShouldReturnsSqlStatement()
+    {
+        // Arrange
+        var sqlCollection = new YeSqlDictionary();
+        var tagName = "GetUsers";
+        var expectedSql = "SELECT* FROM users;";
+        sqlCollection[tagName] = expectedSql;
+
+        // Act
+        string actual = sqlCollection[tagName];
+
+        // Assert
+        actual.Should().Be(expectedSql);
+    }
+
+    [Test]
+    public void TryGetStatement_WhenTagNameIsNull_ShouldThrowArgumentNullException()
+    {
+        // Arrange
+        var sqlCollection = new YeSqlDictionary();
+        var tagName = default(string);
+
+        // Act
+        Action action = () =>
+        {
+            var value = sqlCollection.TryGetStatement(tagName, out _);
+        };
+
+        // Assert
+        action.Should()
+              .Throw<ArgumentNullException>()
+              .WithParameterName(nameof(tagName));
+    }
+
+    [Test]
+    public void TryGetStatement_WhenTagNameIsNotFound_ShouldReturnsFalse()
+    {
+        // Arrange
+        var sqlCollection = new YeSqlDictionary();
+        var tagName = "Test";
+
+        // Act
+        bool actual = sqlCollection.TryGetStatement(tagName, out _);
+
+        // Assert
+        actual.Should().BeFalse();
+    }
+
+    [Test]
+    public void TryGetStatement_WhenTagNameIsFound_ShouldReturnsTrue()
+    {
+        // Arrange
+        var sqlCollection = new YeSqlDictionary();
+        var tagName = "GetUsers";
+        var expectedSql = "SELECT* FROM users;";
+        sqlCollection[tagName] = expectedSql;
+
+        // Act
+        bool actual = sqlCollection.TryGetStatement(tagName, out string currentSql);
+
+        // Asserts
+        actual.Should().BeTrue();
+        currentSql.Should().Be(expectedSql);
+    }
+
+    [Test]
+    public void ToString_WhenConvertingYeSqlDictionaryToString_ShouldReturnsString()
+    {
+        // Arrange
+        var expected =
+        """
+        -- name: GetUsers
+        SELECT* FROM users;
+        -- name: GetProducts
+        SELECT* FROM products;
+        -- name: GetRoles
+        SELECT* FROM roles;
+        """;
+        expected += Environment.NewLine;
+        var sqlCollection = new YeSqlDictionary();
+        sqlCollection["GetUsers"] = "SELECT* FROM users;";
+        sqlCollection["GetProducts"] = "SELECT* FROM products;";
+        sqlCollection["GetRoles"] = "SELECT* FROM roles;";
+
+        // Act
+        string actual = sqlCollection.ToString();
+
+        // Assert
+        actual.Should().Be(expected);
+    }
+
+    [Test]
+    public void ToString_WhenThereAreNoSqlStatements_ShouldReturnsEmptyString()
+    {
+        // Arrange
+        var sqlCollection = new YeSqlDictionary();
+
+        // Act
+        string actual = sqlCollection.ToString();
+
+        // Assert
+        actual.Should().BeEmpty();
+    }
+
+    [Test]
+    public void GetEnumerator_WhenThereAreSqlStatements_ShouldAllowIteratingOverThem()
+    {
+        // Arrange
+        var expected = new List<ModelTag>
+        {
+            new() { Name = "GetUsers", SqlStatement = "SELECT* FROM users;" },
+            new() { Name = "GetProducts", SqlStatement = "SELECT* FROM products;" },
+            new() { Name = "GetRoles", SqlStatement = "SELECT* FROM roles;" }
+        };
+        var sqlCollection = new YeSqlDictionary();
+        sqlCollection["GetUsers"] = "SELECT* FROM users;";
+        sqlCollection["GetProducts"] = "SELECT* FROM products;";
+        sqlCollection["GetRoles"] = "SELECT* FROM roles;";
+
+        // Act
+        IEnumerable<ModelTag> actual = sqlCollection.AsEnumerable();
+
+        // Assert
+        actual.Should().BeEquivalentTo(expected);
+    }
+}