Functional Testing

In large-scale migrations, syntactically correct code is not enough — static code analysis alone cannot verify that a migrated application behaves identically to the original. An API endpoint that returns a different status code, a CLI command that produces different output, or a UI that renders incorrectly can break downstream systems. Proving functional equivalence requires runtime information: actually executing both the origin and target applications and comparing their real outputs. addresses this with built-in functional testing. As part of the migration process, Morph agents automatically generate, run, and verify functional tests that exercise both applications at runtime and compare their behavior side by side. No manual test authoring required. Functional testing works with multi-repo projects — each repository’s tests are tracked and reported independently.

How It Works

Functional tests are woven into the migration lifecycle — they are not a separate step you run after the fact. Here is how they fit in:

Roadmap Generation

The roadmap is established, defining the ordered set of milestones for your migration.

Test Generation

Morph dispatches testing agents for each milestone. Backend testing agents explore the source code, run the application, and record expected behavior for APIs and CLIs. Frontend testing agents navigate the application in a browser, capture screenshots at each step, and optionally record video. This ensures tests capture production-realistic details — bootstrap sequences, authentication, headers, visual layout, and more.

Milestone Execution

During milestone execution, Morph agents run your migrated code and actively verify that functional tests pass as part of the implementation loop. Results appear in each milestone’s test summary and in the project-level Functional Testing dashboard.

Final Validation & Results

After execution completes, all tests are run against the PR branch. Results are reported in the UI so you can verify behavioral equivalence before merging.

What Makes These Tests Different

Aspect	Traditional test suites	Morph functional tests
Authoring	Written manually by engineers	Auto-generated by agents exploring source code
Basis	Specification or developer assumptions	Observed real behavior of the running application
Scope	Varies by team discipline	Systematically covers every discovered entry point
Comparison	Pass/fail against assertions	Side-by-side origin vs. target response comparison
Visual	Not covered	Browser-based screenshot and video capture

Supported Application Types

Morph functional testing covers three categories:

Type	Entry point	Input	Output compared
API	Endpoint (e.g., `/add`, `/health`)	HTTP method, headers, request body	Status code + response body
CLI	Command or subcommand (e.g., `calc add`)	Arguments, flags, stdin	Exit code + stdout/stderr
UI	Page or user flow	Browser interactions (clicks, input)	Screenshots at each step, optional video recording

The Functional Testing Dashboard

The project-level dashboard is accessible from the sidebar. It organizes all test results across two tabs: API/CLI for backend tests and UI for frontend visual tests. If the project only has one type of test, only that tab is shown.

Functional Testing dashboard with API/CLI and UI tabs

API/CLI Tab

The API/CLI tab shows backend functional test results — API endpoint responses and CLI command outputs compared between origin and target.

Summary Bar

At the top, a summary bar provides an at-a-glance view:

Passed/Total — How many tests pass out of the total (e.g., 12/15 passed)
Failed — Count of failing tests (shown only when failures exist)
With comparison — How many tests have origin data available for side-by-side comparison
Avg duration — Average test execution time

API/CLI tab overview with sidebar tree and summary bar

The left sidebar organizes tests in a hierarchy:

Repository — Each repo in the project is a collapsible group
Entity — Within each repo, tests are grouped by entry point:
- For APIs: GET /health, POST /add, etc.
- For CLIs: $ calc add, $ calc health, etc.
Individual tests — Each test case under its entity, showing pass/fail status, duration, and a comparison icon if origin data is available

Use the search bar to filter tests by name, and the status filter (All / Passed / Failed) to focus on what matters.

Detail Panel

Selecting a test opens the detail panel on the right. The content adapts to the protocol type: For API tests:

Endpoint — HTTP method and path (e.g., POST /add)
Expected vs Actual Status — Status codes with mismatch highlighting
Request Body — The payload sent to both origin and target
Target Response — Status code and response body from the migrated application
Origin Response — Response body from the original application (when comparison data is available)
Match indicators — Response Match / Response Mismatch tags with an optional diff view

API test detail panel with origin and target response comparison

For CLI tests:

Command — The full command invocation (e.g., $ calc add 2 3)
Expected vs Actual Exit Code — With mismatch highlighting
Target stdout/stderr — Output from the migrated application
Origin output — Output from the original application (when comparison data is available)
Match indicators — Output Match / Output Mismatch tags with diff view

UI Tab

The UI tab shows frontend visual test results — browser screenshots and recordings captured from the target application, with optional side-by-side comparison against the origin.

Summary Bar

Tests — Total number of UI test flows
Steps — Total screenshot steps across all tests
With origin comparison — How many tests have origin screenshots for side-by-side comparison

Tests are organized by repository, then by test name. Each test entry shows:

Step count — Number of screenshot steps
Recording icon — Indicates a video recording is available
Origin badge — Shows how many steps have origin screenshots (e.g., 3/5 steps have origin)

Step Viewer

Selecting a test step opens the viewer on the right:

Step navigation — Arrow buttons or keyboard arrows to move between steps
Step label — Description of what the step captures (e.g., “Click login button”)
Screenshot comparison — When the test has origin data, screenshots are displayed side by side (Origin on the left, Target on the right). Click to zoom.
Recording mode — Toggle between Steps (screenshot-by-step) and Recording (full video playback) when a recording exists

Use the search bar to filter tests by name, and the comparison filter (All / Has Origin / No Origin) to focus on tests with or without baseline data.

Milestone Test Summary

Each milestone card on the roadmap displays a test summary after execution completes. The summary shows per-repo results:

Backend tests — Repository name with passed/total count and a comparison indicator
Frontend tests — Repository name with total test count and origin comparison count

This gives you a quick signal of migration health without navigating to the full dashboard.

Milestone test summary showing per-repo results

Tips

Review tests early. As soon as tests are generated, skim them in the milestone test summary. If an entry point is missing, it may indicate the agent couldn’t reach it — check your lifecycle setup configuration.
Use the dashboard for stakeholder updates. The passed/total ratio and origin comparison counts are intuitive, non-technical measures of migration completeness.
Combine with rules. If tests reveal a recurring pattern (e.g., missing headers, wrong status codes), create a Rule so Morph handles it in future milestones.
Filter to failures. On the API/CLI tab, use the Failed filter to focus your review on the tests that need attention.

Milestones & Tasks

The three-step process, statuses, task types, and dependencies

Roadmap

High-level view of your migration plan

Reviewing Pull Requests

Best practices for reviewing milestone PRs

Lifecycle Setup

Configure how your project builds and runs

Getting Started

Setting Up Your Migration

Running Your Migration

Customization

Support

Functional Testing