# Extract a Shared Helper from Duplicated Fiber Code with Atlas in 2026 > Atlas helps Fiber developers in 2026 find and refactor duplicated logic into a single, tested helper, ensuring code quality and maintainability. To extract a shared helper from duplicated code in a Fiber application, Atlas leverages semantic search to identify near-identical logic, then uses its write and apply_patch tools to refactor your codebase, ensuring all changes are verified with `go test ./...` and formatted with `gofmt` before committing. ## Key takeaways - Atlas uses semantic search to find duplicated logic in Fiber, even with different variable names. - New Fiber helper modules are created with Atlas's `write` tool, showing a full diff for approval. - Atlas replaces duplicates with helper calls using `apply_patch`, generating one reviewable patch per file. - Every refactoring step is verified by running `go test ./...` and formatted with `gofmt` in your Fiber project. - Atlas understands Fiber's `fasthttp` buffer reuse and prompts for `fiber.Ctx` value copying when necessary. ## How to find duplicated logic in Fiber applications with Atlas? Finding duplicated logic in a Fiber application in 2026 goes beyond simple text matching; Atlas uses `codebase_search` to semantically identify near-duplicate implementations, even when variable names differ. This approach ensures you catch all 100% of the conceptual copies that `grep` might miss. Atlas's `codebase_search` tool is designed to understand the *behavior* of your Fiber code, not just its exact textual representation. When you suspect duplication across several `fiber.Ctx` handlers or middleware, you can ask Atlas to search for the logic. For instance, if you have a common pattern for validating request bodies or handling specific error responses within multiple `app.Group` routes, Atlas can surface these instances. It indexes your code using AST declarations via tree-sitter, allowing it to recognize structural and functional similarities. This is crucial in Fiber, where `fasthttp`'s buffer reuse can lead to subtle but semantically identical patterns appearing in different contexts, making traditional `grep` searches unreliable. Atlas will present the search results, allowing you to `read` each hit and confirm that the copies are genuinely equivalent and suitable for consolidation into a single helper function. ## Creating a new shared helper module for Fiber with Atlas Once duplicated logic is identified, creating a new shared helper module for your Fiber application is a straightforward process with Atlas's `write` tool. This tool allows you to define the new helper function, ensuring it correctly handles `fiber.Ctx` values and respects `fasthttp`'s buffer lifetimes, all while presenting a full diff for approval before 1 byte is written. After confirming the duplicated logic, you'll use Atlas's `write` tool to create the new Go file for your shared helper. For example, you might create `internal/helpers/validation.go` to house a common validation function. Atlas will draft the code for this new helper, ensuring it's idiomatic Go and compatible with Fiber's `fiber.Ctx` context. A critical consideration in Fiber, due to `fasthttp`'s underlying buffer reuse, is ensuring that any `ctx` values or derived data retained past the handler are explicitly copied. Atlas is aware of this and will prompt you to copy such values. Before creating the file, Atlas presents a unified diff of the proposed changes, allowing you to review and approve the new module's content. This permission-gated step ensures you maintain full control over your codebase, and Atlas will automatically run `gofmt` on the new file to maintain consistent styling. ## Replacing duplicated Fiber code with helper calls using Atlas Replacing each instance of duplicated Fiber code with a call to your new shared helper is handled by Atlas's `apply_patch` tool, ensuring each modification is independently reviewable. This process involves 1 patch per file, allowing granular control and easy rollback if any issue arises during testing with `go test (app.Test)`. With the shared helper function now available, Atlas uses `apply_patch` to systematically replace each identified duplicate with a call to the new helper. For example, if `handlers/user.go` and `handlers/product.go` both contained the same validation logic, Atlas would generate two separate patches. Each patch replaces the duplicated block with a concise call like `helpers.ValidateRequest(c)`. This 'one file per patch' strategy is vital for reviewability, especially in a team environment. After Atlas applies a patch to a file, it will prompt you to run your test suite using `bash` to execute `go test ./...`. This immediate feedback loop, leveraging Fiber's `app.Test()` capabilities, ensures that each refactoring step does not introduce regressions. If tests pass, Atlas proceeds to the next duplicate; if they fail, you can revert the patch and refine the helper or the replacement logic. Finally, Atlas will run `gofmt` on the touched files to ensure code style consistency across your Fiber project. ## Ensuring Fiber code quality and safety during refactoring with Atlas Maintaining code quality and ensuring safety during refactoring is paramount, especially in a high-performance framework like Fiber. Atlas integrates directly with your existing Go toolchain, running `go test ./...` after every `apply_patch` operation and `gofmt` on all touched files, providing 2 layers of automated verification. Atlas prioritizes safety and reviewability throughout the refactoring process. Every tool call, from `codebase_search` to `write` and `apply_patch`, is permission-gated, requiring your explicit approval. When creating a new helper or modifying existing Fiber handlers, Atlas presents a unified diff for your review. After each `apply_patch` operation that replaces duplicated code, Atlas automatically suggests running your Fiber application's test suite. You can approve this `bash` command to execute `go test ./...`, which will run all tests, including those using `app.Test()`. This immediate testing ensures that the refactoring hasn't broken existing functionality. Furthermore, Atlas automatically runs `gofmt` on any file it modifies, ensuring your codebase adheres to standard Go formatting conventions. Once all duplicates are replaced and tests pass, Atlas can help you `grep` for any surviving copies of the original logic, providing a final verification step before you stage and create commits on your behalf. ## Steps 1. Run Atlas in your Fiber module where `go.mod` requires `github.com/gofiber/fiber/v3`. 2. Ask Atlas to `codebase_search` for the behavior of the duplicated logic across your `app.Group` routes or `fiber.Ctx` handlers, then `read` the results to confirm equivalence. 3. Use Atlas's `write` tool to create the new shared helper file (e.g., `internal/helpers/common.go`), reviewing the full diff and ensuring `fiber.Ctx` values are copied if retained past the handler. 4. Instruct Atlas to `apply_patch` to replace the first instance of duplicated code with a call to your new helper, reviewing the diff for the specific file (e.g., `handlers/user.go`). 5. Approve Atlas's `bash` command to run `go test ./...` (including `app.Test()`) to verify the change, then let Atlas run `gofmt` on the touched file. 6. Repeat the `apply_patch`, `bash` (`go test ./...`), and `gofmt` steps for each remaining duplicate until all instances are replaced. 7. Finally, use Atlas's `grep` tool to search for any surviving copies of the original logic, ensuring a complete refactor. ## FAQ ### How does Atlas find duplicated code in Fiber better than `grep`? Atlas uses `codebase_search` with AST declarations and semantic retrieval, allowing it to find functionally identical logic in your Fiber application even if variable names or minor structural details differ, which `grep` would miss. ### Can Atlas handle `fasthttp` buffer lifetime issues when refactoring Fiber handlers? Yes, Atlas is aware of `fasthttp`'s buffer reuse in Fiber. When extracting logic that retains `fiber.Ctx` values past the handler, Atlas will prompt you to explicitly copy those values to prevent unexpected behavior. ### How does Atlas ensure my Fiber application still works after refactoring? After each `apply_patch` operation that replaces duplicated code, Atlas prompts you to run `go test ./...` via `bash`. This immediately executes your Fiber application's test suite, including `app.Test()`, to catch any regressions. ### Will Atlas automatically format my Go files in a Fiber project? Yes, Atlas automatically runs `gofmt` on any Go file it modifies or creates, ensuring your Fiber codebase maintains consistent formatting according to standard Go practices. ### What if I don't like a change Atlas proposes for my Fiber code? Every Atlas tool call is permission-gated. Before `write` creates a file or `apply_patch` modifies one, Atlas presents a unified diff for your review and approval. You can deny any change or ask Atlas to revise it. ### Can Atlas help me commit the refactored Fiber code? Yes, after you've approved all changes and verified tests pass, Atlas can read your git status, stage the changes, and create commits on your behalf, streamlining the entire refactoring workflow for your Fiber project. --- Canonical HTML: https://runatlas.sh/resources/stacks/extract-a-shared-helper-from-duplicated-code-in-fiber Source of truth: aeo_pages row `/resources/stacks/extract-a-shared-helper-from-duplicated-code-in-fiber` (segment: Stacks) (this file is generated from it, never hand-edited). Licence: Atlas is proprietary with a free core. It is not open source and there is no public source repository.