diff --git a/docs/keywords/format.md b/docs/keywords/format.md
index a5c4f15..4f84305 100644
--- a/docs/keywords/format.md
+++ b/docs/keywords/format.md
@@ -52,4 +52,5 @@
 **USAGE:**
 `FORMAT(123.456, "C2")` → "$123.46"
 `FORMAT(NOW(), "yyyy-MM-dd HH:mm")` → "2024-01-15 14:30"
-`FORMAT(0.15, "0%")` → "15%"
\ No newline at end of file
+`FORMAT(0.15, "0%")` → "15%"
+
diff --git a/src/services/keywords/format.rs b/src/services/keywords/format.rs
index d085dd8..ca26177 100644
--- a/src/services/keywords/format.rs
+++ b/src/services/keywords/format.rs
@@ -191,3 +191,270 @@ fn apply_text_placeholders(value: &str, pattern: &str) -> String {
 
     result
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use rhai::Engine;
+
+    fn create_engine() -> Engine {
+        let mut engine = Engine::new();
+        format_keyword(&mut engine);
+        engine
+    }
+
+    #[test]
+    fn test_numeric_formatting_basic() {
+        let engine = create_engine();
+        
+        // Teste formatação básica
+        assert_eq!(
+            engine.eval::<String>("FORMAT 1234.567 \"n\"").unwrap(),
+            "1234.57"
+        );
+        assert_eq!(
+            engine.eval::<String>("FORMAT 1234.5 \"F\"").unwrap(),
+            "1234.50"
+        );
+        assert_eq!(
+            engine.eval::<String>("FORMAT 1234.567 \"f\"").unwrap(),
+            "1234.567"
+        );
+        assert_eq!(
+            engine.eval::<String>("FORMAT 0.85 \"0%\"").unwrap(),
+            "85%"
+        );
+    }
+
+    #[test]
+    fn test_numeric_formatting_with_locale() {
+        let engine = create_engine();
+        
+        // Teste formatação numérica com locale
+        assert_eq!(
+            engine.eval::<String>("FORMAT 1234.56 \"N[en]\"").unwrap(),
+            "1,234.56"
+        );
+        assert_eq!(
+            engine.eval::<String>("FORMAT 1234.56 \"N[pt]\"").unwrap(),
+            "1.234,56"
+        );
+        assert_eq!(
+            engine.eval::<String>("FORMAT 1234.56 \"N[fr]\"").unwrap(),
+            "1 234,56"
+        );
+    }
+
+    #[test]
+    fn test_currency_formatting() {
+        let engine = create_engine();
+        
+        // Teste formatação monetária
+        assert_eq!(
+            engine.eval::<String>("FORMAT 1234.56 \"C[en]\"").unwrap(),
+            "$1,234.56"
+        );
+        assert_eq!(
+            engine.eval::<String>("FORMAT 1234.56 \"C[pt]\"").unwrap(),
+            "R$ 1.234,56"
+        );
+        assert_eq!(
+            engine.eval::<String>("FORMAT 1234.56 \"C[fr]\"").unwrap(),
+            "€1 234,56"
+        );
+    }
+
+    #[test]
+    fn test_numeric_decimals_precision() {
+        let engine = create_engine();
+        
+        // Teste precisão decimal
+        assert_eq!(
+            engine.eval::<String>("FORMAT 1234.5678 \"N0[en]\"").unwrap(),
+            "1,235"
+        );
+        assert_eq!(
+            engine.eval::<String>("FORMAT 1234.5678 \"N1[en]\"").unwrap(),
+            "1,234.6"
+        );
+        assert_eq!(
+            engine.eval::<String>("FORMAT 1234.5678 \"N3[en]\"").unwrap(),
+            "1,234.568"
+        );
+        assert_eq!(
+            engine.eval::<String>("FORMAT 1234.5 \"C0[en]\"").unwrap(),
+            "$1,235"
+        );
+    }
+
+    #[test]
+    fn test_date_formatting() {
+        let engine = create_engine();
+        
+        // Teste formatação de datas
+        let result = engine.eval::<String>("FORMAT \"2024-03-15 14:30:25\" \"yyyy-MM-dd HH:mm:ss\"").unwrap();
+        assert_eq!(result, "2024-03-15 14:30:25");
+
+        let result = engine.eval::<String>("FORMAT \"2024-03-15 14:30:25\" \"dd/MM/yyyy\"").unwrap();
+        assert_eq!(result, "15/03/2024");
+
+        let result = engine.eval::<String>("FORMAT \"2024-03-15 14:30:25\" \"MM/dd/yy\"").unwrap();
+        assert_eq!(result, "03/15/24");
+
+        let result = engine.eval::<String>("FORMAT \"2024-03-15 14:30:25\" \"HH:mm\"").unwrap();
+        assert_eq!(result, "14:30");
+    }
+
+    #[test]
+    fn test_date_formatting_12h() {
+        let engine = create_engine();
+        
+        // Teste formato 12h
+        let result = engine.eval::<String>("FORMAT \"2024-03-15 14:30:25\" \"hh:mm tt\"").unwrap();
+        assert_eq!(result, "02:30 PM");
+
+        let result = engine.eval::<String>("FORMAT \"2024-03-15 09:30:25\" \"hh:mm tt\"").unwrap();
+        assert_eq!(result, "09:30 AM");
+
+        let result = engine.eval::<String>("FORMAT \"2024-03-15 00:30:25\" \"h:mm t\"").unwrap();
+        assert_eq!(result, "12:30 A");
+    }
+
+    #[test]
+    fn test_text_formatting() {
+        let engine = create_engine();
+        
+        // Teste formatação de texto
+        assert_eq!(
+            engine.eval::<String>("FORMAT \"hello\" \"Prefix: @\"").unwrap(),
+            "Prefix: hello"
+        );
+        assert_eq!(
+            engine.eval::<String>("FORMAT \"HELLO\" \"Result: &!\"").unwrap(),
+            "Result: hello!"
+        );
+        assert_eq!(
+            engine.eval::<String>("FORMAT \"hello\" \"RESULT: >\"").unwrap(),
+            "RESULT: HELLO"
+        );
+        assert_eq!(
+            engine.eval::<String>("FORMAT \"Hello\" \"<>\"").unwrap(),
+            "hello>"
+        );
+    }
+
+    #[test]
+    fn test_mixed_patterns() {
+        let engine = create_engine();
+        
+        // Teste padrões mistos
+        assert_eq!(
+            engine.eval::<String>("FORMAT \"hello\" \"@ World!\"").unwrap(),
+            "hello World!"
+        );
+        assert_eq!(
+            engine.eval::<String>("FORMAT \"test\" \"< & > ! @\"").unwrap(),
+            "test test TEST ! test"
+        );
+    }
+
+    #[test]
+    fn test_edge_cases() {
+        let engine = create_engine();
+        
+        // Teste casos extremos
+        assert_eq!(
+            engine.eval::<String>("FORMAT 0 \"n\"").unwrap(),
+            "0.00"
+        );
+        assert_eq!(
+            engine.eval::<String>("FORMAT -1234.56 \"N[en]\"").unwrap(),
+            "-1,234.56"
+        );
+        assert_eq!(
+            engine.eval::<String>("FORMAT \"\" \"@\"").unwrap(),
+            ""
+        );
+        assert_eq!(
+            engine.eval::<String>("FORMAT \"test\" \"\"").unwrap(),
+            ""
+        );
+    }
+
+    #[test]
+    fn test_invalid_patterns_fallback() {
+        let engine = create_engine();
+        
+        // Teste padrões inválidos (devem fallback para string)
+        assert_eq!(
+            engine.eval::<String>("FORMAT 123.45 \"invalid\"").unwrap(),
+            "123.45"
+        );
+        assert_eq!(
+            engine.eval::<String>("FORMAT \"text\" \"unknown\"").unwrap(),
+            "unknown"
+        );
+    }
+
+    #[test]
+    fn test_milliseconds_formatting() {
+        let engine = create_engine();
+        
+        // Teste milissegundos
+        let result = engine.eval::<String>("FORMAT \"2024-03-15 14:30:25.123\" \"HH:mm:ss.fff\"").unwrap();
+        assert_eq!(result, "14:30:25.123");
+    }
+
+    #[test]
+    fn test_parse_pattern_function() {
+        // Teste direto da função parse_pattern
+        assert_eq!(parse_pattern("C[en]"), ("C".to_string(), 2, "en".to_string()));
+        assert_eq!(parse_pattern("N3[pt]"), ("N".to_string(), 3, "pt".to_string()));
+        assert_eq!(parse_pattern("C0[fr]"), ("C".to_string(), 0, "fr".to_string()));
+        assert_eq!(parse_pattern("N"), ("N".to_string(), 2, "en".to_string()));
+        assert_eq!(parse_pattern("C2"), ("C".to_string(), 2, "en".to_string()));
+    }
+
+    #[test]
+    fn test_locale_functions() {
+        // Teste funções de locale
+        assert!(matches!(get_locale("en"), Locale::en));
+        assert!(matches!(get_locale("pt"), Locale::pt));
+        assert!(matches!(get_locale("fr"), Locale::fr));
+        assert!(matches!(get_locale("invalid"), Locale::en)); // fallback
+
+        assert_eq!(get_currency_symbol("en"), "$");
+        assert_eq!(get_currency_symbol("pt"), "R$ ");
+        assert_eq!(get_currency_symbol("fr"), "€");
+        assert_eq!(get_currency_symbol("invalid"), "$"); // fallback
+    }
+
+    #[test]
+    fn test_apply_text_placeholders() {
+        // Teste direto da função apply_text_placeholders
+        assert_eq!(apply_text_placeholders("Hello", "@"), "Hello");
+        assert_eq!(apply_text_placeholders("Hello", "&"), "hello");
+        assert_eq!(apply_text_placeholders("Hello", ">"), "HELLO");
+        assert_eq!(apply_text_placeholders("Hello", "Prefix: @!"), "Prefix: Hello!");
+        assert_eq!(apply_text_placeholders("Hello", "<>"), "hello>");
+    }
+
+    #[test]
+    fn test_expression_parameters() {
+        let engine = create_engine();
+        
+        // Teste com expressões como parâmetros
+        assert_eq!(
+            engine.eval::<String>("let x = 1000.50; FORMAT x \"N[en]\"").unwrap(),
+            "1,000.50"
+        );
+        assert_eq!(
+            engine.eval::<String>("FORMAT (500 + 500) \"n\"").unwrap(),
+            "1000.00"
+        );
+        assert_eq!(
+            engine.eval::<String>("let pattern = \"@ World\"; FORMAT \"Hello\" pattern").unwrap(),
+            "Hello World"
+        );
+    }
+}
\ No newline at end of file