Checks for diff changes before displaying the code snippet (#751)

package-lock.json

@@ -15,6 +15,7 @@
       },
       "devDependencies": {
         "@types/mime-types": "^2.1.4",
+        "@types/minimatch": "^5.1.2",
         "@vitest/coverage-v8": "^3.1.1",
         "esbuild": "^0.25.4",
         "eslint": "^9.24.0",

package.json

@@ -46,6 +46,7 @@
   ],
   "devDependencies": {
     "@types/mime-types": "^2.1.4",
+    "@types/minimatch": "^5.1.2",
     "@vitest/coverage-v8": "^3.1.1",
     "esbuild": "^0.25.4",
     "eslint": "^9.24.0",
@@ -55,13 +56,12 @@
     "eslint-plugin-react": "^7.37.5",
     "eslint-plugin-react-hooks": "^5.2.0",
     "globals": "^16.0.0",
+    "json": "^11.0.0",
     "lodash": "^4.17.21",
     "memfs": "^4.17.2",
     "prettier": "^3.5.3",
     "react-devtools-core": "^4.28.5",
     "typescript-eslint": "^8.30.1",
-    "yargs": "^17.7.2",
-    "json": "^11.0.0"
-  },
-  "dependencies": {}
+    "yargs": "^17.7.2"
+  }
 }

packages/core/src/tools/edit.test.ts

@@ -547,4 +547,57 @@ describe('EditTool', () => {
       );
     });
   });
+
+  describe('getDescription', () => {
+    it('should return "No file changes to..." if old_string and new_string are the same', () => {
+      const testFileName = 'test.txt';
+      const params: EditToolParams = {
+        file_path: path.join(rootDir, testFileName),
+        old_string: 'identical_string',
+        new_string: 'identical_string',
+      };
+      // shortenPath will be called internally, resulting in just the file name
+      expect(tool.getDescription(params)).toBe(
+        `No file changes to ${testFileName}`,
+      );
+    });
+
+    it('should return a snippet of old and new strings if they are different', () => {
+      const testFileName = 'test.txt';
+      const params: EditToolParams = {
+        file_path: path.join(rootDir, testFileName),
+        old_string: 'this is the old string value',
+        new_string: 'this is the new string value',
+      };
+      // shortenPath will be called internally, resulting in just the file name
+      // The snippets are truncated at 30 chars + '...'
+      expect(tool.getDescription(params)).toBe(
+        `${testFileName}: this is the old string value => this is the new string value`,
+      );
+    });
+
+    it('should handle very short strings correctly in the description', () => {
+      const testFileName = 'short.txt';
+      const params: EditToolParams = {
+        file_path: path.join(rootDir, testFileName),
+        old_string: 'old',
+        new_string: 'new',
+      };
+      expect(tool.getDescription(params)).toBe(`${testFileName}: old => new`);
+    });
+
+    it('should truncate long strings in the description', () => {
+      const testFileName = 'long.txt';
+      const params: EditToolParams = {
+        file_path: path.join(rootDir, testFileName),
+        old_string:
+          'this is a very long old string that will definitely be truncated',
+        new_string:
+          'this is a very long new string that will also be truncated',
+      };
+      expect(tool.getDescription(params)).toBe(
+        `${testFileName}: this is a very long old string... => this is a very long new string...`,
+      );
+    });
+  });
 });

packages/core/src/tools/edit.ts

@@ -379,6 +379,9 @@ Expectation for required parameters:
       params.new_string.split('\n')[0].substring(0, 30) +
       (params.new_string.length > 30 ? '...' : '');
 
+    if (params.old_string === params.new_string) {
+      return `No file changes to ${shortenPath(relativePath)}`;
+    }
     return `${shortenPath(relativePath)}: ${oldStringSnippet} => ${newStringSnippet}`;
   }