diff --git a/src/to-json/src/tests.rs b/src/to-json/src/tests.rs
index 3a63c23..ee74871 100644
--- a/src/to-json/src/tests.rs
+++ b/src/to-json/src/tests.rs
@@ -1,71 +1,80 @@
-use crate::convert::to_json;
-
-const JSON_TEST_CONTENT: &str = r#"
-{
-  "int": 123,
-  "bool": true,
-  "float": 3.141592,
-  "string": "json test",
-  "array": [1, 2, 3, 4, 5],
-  "object": {
-    "sub": "test"
-  }
-}
-"#;
-
-const YAML_TEST_CONTENT: &str = r#"
-int: 123
-bool: true
-float: 3.141592
-string: "json test"
-array:
- - 1
- - 2
- - 3
- - 4
- - 5
-object:
-  sub: test
-"#;
-
-const TOML_TEST_CONTENT: &str = r#"
-int = 123
-bool = true
-float = 3.141592
-string = "json test"
-array = [ 1, 2, 3, 4, 5 ]
-
-[object]
-sub = "test"
-"#;
-
-fn format_json(raw: &str) -> String {
-    match to_json(raw) {
-        Some(data) => data,
-        None => panic!("JSON format error"),
-    }
-}
-
-#[test]
-fn json_to_json() {
-    assert_eq!(
-        format_json(JSON_TEST_CONTENT),
-        format_json(&to_json(JSON_TEST_CONTENT).unwrap()),
-    );
-}
-
-#[test]
-fn yaml_to_json() {
-    assert_eq!(
-        format_json(JSON_TEST_CONTENT),
-        format_json(&to_json(YAML_TEST_CONTENT).unwrap()),
-    );
-}
-
-#[test]
-fn toml_to_json() {
-    assert_eq!(
-        format_json(JSON_TEST_CONTENT),
-        format_json(&to_json(TOML_TEST_CONTENT).unwrap()),
-    );
-}
+use crate::convert::to_json;
+
+#[allow(dead_code)]
+const JSON_TEST_CONTENT: &str = r#"
+{
+  "int": 123,
+  "bool": true,
+  "float": 3.141592,
+  "string": "json test",
+  "array": [1, 2, 3, 4, 5],
+  "object": {
+    "sub": "test"
+  }
+}
+"#;
+
+#[allow(dead_code)]
+const YAML_TEST_CONTENT: &str = r#"
+int: 123
+bool: true
+float: 3.141592
+string: "json test"
+array:
+ - 1
+ - 2
+ - 3
+ - 4
+ - 5
+object:
+  sub: test
+"#;
+
+#[allow(dead_code)]
+const TOML_TEST_CONTENT: &str = r#"
+int = 123
+bool = true
+float = 3.141592
+string = "json test"
+array = [ 1, 2, 3, 4, 5 ]
+
+[object]
+sub = "test"
+"#;
+
+
+mod tests {
+    use super::*;
+
+    #[allow(dead_code)]
+    fn format_json(raw: &str) -> String {
+        match to_json(raw) {
+            Some(data) => data,
+            None => panic!("JSON format error"),
+        }
+    }
+
+    #[test]
+    fn json_to_json() {
+        assert_eq!(
+            format_json(JSON_TEST_CONTENT),
+            format_json(&to_json(JSON_TEST_CONTENT).unwrap()),
+        );
+    }
+
+    #[test]
+    fn yaml_to_json() {
+        assert_eq!(
+            format_json(JSON_TEST_CONTENT),
+            format_json(&to_json(YAML_TEST_CONTENT).unwrap()),
+        );
+    }
+
+    #[test]
+    fn toml_to_json() {
+        assert_eq!(
+            format_json(JSON_TEST_CONTENT),
+            format_json(&to_json(TOML_TEST_CONTENT).unwrap()),
+        );
+    }
+}