diff --git a/crates/mother-core/src/scanner/tests/tests_language.rs b/crates/mother-core/src/scanner/tests/tests_language.rs
index 2894832..d0c9326 100644
--- a/crates/mother-core/src/scanner/tests/tests_language.rs
+++ b/crates/mother-core/src/scanner/tests/tests_language.rs
@@ -56,3 +56,82 @@ fn test_language_display() {
     assert_eq!(format!("{}", Language::SysML), "sysml");
     assert_eq!(format!("{}", Language::KerML), "kerml");
 }
+
+#[test]
+fn test_language_extensions() {
+    // Test that each language returns the correct extensions
+    assert_eq!(Language::Rust.extensions(), &["rs"]);
+    assert_eq!(Language::Python.extensions(), &["py"]);
+    assert_eq!(Language::TypeScript.extensions(), &["ts", "tsx"]);
+    assert_eq!(
+        Language::JavaScript.extensions(),
+        &["js", "jsx", "mjs", "cjs"]
+    );
+    assert_eq!(Language::Go.extensions(), &["go"]);
+    assert_eq!(Language::SysML.extensions(), &["sysml"]);
+    assert_eq!(Language::KerML.extensions(), &["kerml"]);
+}
+
+#[test]
+fn test_extensions_consistency_with_from_extension() {
+    // Verify that all extensions returned by extensions() can be parsed by from_extension()
+    for language in [
+        Language::Rust,
+        Language::Python,
+        Language::TypeScript,
+        Language::JavaScript,
+        Language::Go,
+        Language::SysML,
+        Language::KerML,
+    ] {
+        for ext in language.extensions() {
+            assert_eq!(
+                Language::from_extension(ext),
+                Some(language),
+                "Extension '{}' should map to {:?}",
+                ext,
+                language
+            );
+        }
+    }
+}
+
+#[test]
+fn test_extensions_are_not_empty() {
+    // Ensure every language has at least one extension
+    for language in [
+        Language::Rust,
+        Language::Python,
+        Language::TypeScript,
+        Language::JavaScript,
+        Language::Go,
+        Language::SysML,
+        Language::KerML,
+    ] {
+        assert!(
+            !language.extensions().is_empty(),
+            "{:?} should have at least one extension",
+            language
+        );
+    }
+}
+
+#[test]
+fn test_extensions_multiple_for_typescript() {
+    // TypeScript should support both .ts and .tsx files
+    let extensions = Language::TypeScript.extensions();
+    assert_eq!(extensions.len(), 2);
+    assert!(extensions.contains(&"ts"));
+    assert!(extensions.contains(&"tsx"));
+}
+
+#[test]
+fn test_extensions_multiple_for_javascript() {
+    // JavaScript should support .js, .jsx, .mjs, and .cjs files
+    let extensions = Language::JavaScript.extensions();
+    assert_eq!(extensions.len(), 4);
+    assert!(extensions.contains(&"js"));
+    assert!(extensions.contains(&"jsx"));
+    assert!(extensions.contains(&"mjs"));
+    assert!(extensions.contains(&"cjs"));
+}