# Developer first Code Coverage platform

> Discover what untested code is causing errors & how to avoid similar errors in the future with Sentry's Codecov integration. Try Codecov for free.

**URL:** https://sentry.io/product/code-coverage/

---

See the untested code causing errors - or whether it’s partially or fully covered - directly in your stack trace to avoid similar errors from happening in the future.

## Features

### See code coverage at every stage of development.

Check and correct code coverage before release in your code host, and find it in the stack trace when things get real.

### View all your coverage in one place.

Aggregate coverage reporting, see changes over time, and get cross-repo analytics so you have visibility across all your services.

### Group your testing concerns.

Create custom statuses and group coverage in your repo without modifying your test setup using Flags and Components.

## More Features

- **Code Coverage**: Understand test coverage of code. — [Learn more](https://docs.codecov.com/docs/about-code-coverage)

- **Coverage by Project**: Track coverage metrics for individual projects. — [Learn more](https://docs.codecov.com/docs/common-recipe-list#show-project-coverage-changes-on-the-pull-request-comment)

- **Coverage by Change/Patch**: Monitor coverage with each code change. — [Learn more](https://docs.codecov.io/docs/patch-coverage/)

- **PR Comments**: Feedback on pull requests with coverage insights. — [Learn more](https://docs.codecov.io/docs/github-checks/)

- **Flags**: Define coverage requirements for projects. — [Learn more](https://docs.codecov.io/docs/flags/)

## FAQ

**What do I need to do to see test coverage data in my Sentry issues?**

You must be on a Sentry Team or Business plan - [check your Sentry plan subscription](https://sentry.io/settings/billing/overview/). Additionally, make sure you have Sentry’s GitHub integration installed and [Code Mappings](https://docs.sentry.io/product/issues/suspect-commits/#2-set-up-code-mappings) configured. This will help Sentry determine which source code files to fetch for coverage information.

Codecov Requirements

You must be an existing Codecov customer. If you’re not, [getting started](https://about.codecov.io/sign-up-sentry-codecov/) with Codecov takes a few minutes and you can try it for free for 14 days. [Sign up here](https://about.codecov.io/sign-up-sentry-codecov/).

**What is code coverage and why does it matter?**

There is a direct correlation between poor test coverage and incidents.

Code coverage is a testing technique that informs what code is tested and what is not. It is often represented as a percentage of the number of lines of code tested versus the entire codebase. Without building these tests and having proper test coverage, it's easy to miss preventable bugs before shipping to production which impacts the user experience and can have your developers scrambling to find fixes.

With code coverage solutions like Codecov, you can get a holistic view of your code coverage so you can do things like understand what code is covered when there are drops in code coverage. You can provide blocking status checks on PRs to prevent merging code that has not been well-tested so you and your team can build more reliable and secure code.

To learn more, check out [Codecov's free ebook](https://about.codecov.io/resource/what-is-code-coverage/).

## Of course we have more content

- [What is code coverage eBook](https://about.codecov.io/resource/what-is-code-coverage/): To get an understanding of code coverage, we have to talk about testing code. A test runs a piece of code and ensures that the system produces the expected behavior given some input.

- [Codecov on-demand demo](https://about.codecov.io/codecov-get-demo/): Codecov is the all-in-one code coverage reporting solution for any test suite — giving developers actionable insights to deploy reliable code with confidence.

- [Code coverage insights - now in your stack trace](https://blog.sentry.io/code-coverage-insights-now-in-your-stack-trace-announcing-our-codecov/): Using Codecov’s integration with Sentry allows you to see the untested code causing errors directly in the Sentry Issue stack trace.

- [Bringing Codecov into the Sentry family: where code coverage meets application monitoring](https://blog.sentry.io/bringing-codecov-into-the-sentry-family-where-code-coverage-meets-application-monitoring/): Codecov makes coverage actionable for over two dozen test frameworks, and has helped over a million software developers improve their approach to testing, coverage, and code reliability.

## Testimonials

> Codecov unifies coverage data in one place and visualizes the data very well. It also provides the API to query the data for analytics purposes. For our usage, it provides feedback on pull requests directly and nicely improves the developer experience to shorten the feedback loop so that they can fix their issues more quickly.

> — Jun Li, Lyft

> As we’ve created this positive feedback loop of increased coverage, it’s a reward for adding more test coverage. Maybe you’re not refactoring something, you’re just adding some functionality. You get to increase test coverage while paying off tech debt.

> — Dave Bullock, UJET

## Quick Start

### Python

Install the Sentry Python SDK with pip

```bash
pip install sentry-sdk
```

Configuration should happen as early as possible in your application's lifecycle.

```python
import sentry_sdk

sentry_sdk.init(
  dsn="https://examplePublicKey@o0.ingest.sentry.io/0",
  # Add data like request headers and IP for users, if applicable;
  # see https://docs.sentry.io/platforms/python/data-management/data-collected/ for more info
  send_default_pii=True,
  # Set traces_sample_rate to 1.0 to capture 100%
  # of transactions for tracing.
  traces_sample_rate=1.0,
  #Enable logs to be sent to Sentry
  enable_logs=True,
  # To collect profiles for all profile sessions,
  # set profile_session_sample_rate to 1.0.
  profile_session_sample_rate=1.0,
  # Profiles will be automatically collected while
  # there is an active span.
  profile_lifecycle="trace",
)
```

### JavaScript

Install the Sentry JavaScript SDK with npm

```bash
npm install @sentry/browser --save
```

Configuration should happen as early as possible in your application's lifecycle.

```javascript
import * as Sentry from "@sentry/browser";

Sentry.init({
  dsn: "https://examplePublicKey@o0.ingest.sentry.io/0",
  // Adds request headers and IP for users, for more info visit:
  // https://docs.sentry.io/platforms/javascript/configuration/options/#sendDefaultPii
  sendDefaultPii: true,
  // Set tracesSampleRate to 1.0 to capture 100%
  // of transactions for tracing.
  tracesSampleRate: 1.0,
  // Set tracePropagationTargets to control for which URLs trace propagation should be enabled
  tracePropagationTargets: ["localhost", /^https:\/\/yourserver\.io\/api/],
  // Enable logs to be sent to Sentry
  enableLogs: true,
  // Set profilesSampleRate to 1.0 to profile every transaction.
  // Since profilesSampleRate is relative to tracesSampleRate,
  // the final profiling rate can be computed as tracesSampleRate * profilesSampleRate
  // For example, a tracesSampleRate of 0.5 and profilesSampleRate of 0.5 would
  // result in 25% of transactions being profiled (0.5*0.5=0.25)
  profilesSampleRate: 1.0,
  integrations: [
    Sentry.browserTracingIntegration(),
    Sentry.browserProfilingIntegration(),
  ],
});
```

### React

Run the command for your preferred package manager to add the Sentry SDK to your application:

```bash
npm install @sentry/react --save
```

To import and initialize Sentry, create a file in your project's root directory, for example, `instrument.js`, and add the following code:

```javascript
import * as Sentry from "@sentry/react";

Sentry.init({
  dsn: "https://examplePublicKey@o0.ingest.sentry.io/0",
  // Adds request headers and IP for users, for more info visit:
  // https://docs.sentry.io/platforms/javascript/guides/react/configuration/options/#sendDefaultPii
  sendDefaultPii: true,
  // Set tracesSampleRate to 1.0 to capture 100%
  // of transactions for tracing.
  // Learn more at
  // https://docs.sentry.io/platforms/javascript/configuration/options/#traces-sample-rate
  tracesSampleRate: 1.0,
  // Set `tracePropagationTargets` to control for which URLs trace propagation should be enabled
  tracePropagationTargets: [/^//, /^https://yourserver.io/api/],
  // Enable logs to be sent to Sentry
  enableLogs: true,
  // Set profilesSampleRate to 1.0 to profile every transaction.
  // Since profilesSampleRate is relative to tracesSampleRate,
  // the final profiling rate can be computed as tracesSampleRate * profilesSampleRate
  // For example, a tracesSampleRate of 0.5 and profilesSampleRate of 0.5 would
  // result in 25% of transactions being profiled (0.5*0.5=0.25)
  profilesSampleRate: 1.0,
  integrations: [
    // If you're using react router, use the integration for your react router version instead.
    // Learn more at
    // https://docs.sentry.io/platforms/javascript/guides/react/features/react-router/
    Sentry.browserTracingIntegration(),
    Sentry.browserProfilingIntegration(),
  ],
});
```

Initialize Sentry as early as possible in your application. We recommend putting the import of your initialization code as the first import in your app's entry point:

```javascript
// Sentry initialization should be imported first!
import "./instrument";
import App from "./App";
import { createRoot } from "react-dom/client";

const container = document.getElementById("app");
const root = createRoot(container);
root.render(<App />);
```

To make sure Sentry captures all your app's errors, configure error handling based on your React version. 
 For React versions 19 and up:  

```javascript
import { createRoot } from "react-dom/client";
import * as Sentry from '@sentry/react';

const container = document.getElementById("app");
const root = createRoot(container, {
  // Callback called when an error is thrown and not caught by an ErrorBoundary.
  onUncaughtError: Sentry.reactErrorHandler((error, errorInfo) => {
    console.warn('Uncaught error', error, errorInfo.componentStack);
  }),
  // Callback called when React catches an error in an ErrorBoundary.
  onCaughtError: Sentry.reactErrorHandler(),
  // Callback called when React automatically recovers from errors.
  onRecoverableError: Sentry.reactErrorHandler(),
});
root.render();
```

For React versions 18 and below, use the ErrorBoundary component to automatically send errors from specific component trees to Sentry and provide a fallback UI:

```javascript
import React from "react";
import * as Sentry from "@sentry/react";

<Sentry.ErrorBoundary fallback={<p>An error has occurred</p>}>
  <Example />
</Sentry.ErrorBoundary>;
```

### Next.js

To install Sentry using the installation wizard, run thrun the following command and step through the prompts:

```bash
npx @sentry/wizard@latest -i nextjs
```

For manual installation run the following command and use the following configurations:

```bash
npm install @sentry/nextjs --save
```

Extend your app's default Next.js options by adding code with `withSentryConfig` into your `next.config.(js|mjs)` file:

```javascript
const { withSentryConfig } = require("@sentry/nextjs");
const nextConfig = {
  // Your existing Next.js configuration
};
// Make sure adding Sentry options is the last code to run before exporting
module.exports = withSentryConfig(nextConfig, {
  org: "example-org",
  project: "example-project",
  // Only print logs for uploading source maps in CI
  // Set to `true` to suppress logs
  silent: !process.env.CI,
  // Automatically tree-shake Sentry logger statements to reduce bundle size
  disableLogger: true,
});
```

#### Client-Side Configuration

```javascript
import * as Sentry from "@sentry/nextjs";
Sentry.init({
  dsn: "https://examplePublicKey@o0.ingest.sentry.io/0",
  // Adds request headers and IP for users, for more info visit:
  // https://docs.sentry.io/platforms/javascript/guides/nextjs/configuration/options/#sendDefaultPii
  sendDefaultPii: true,
  // Set tracesSampleRate to 1.0 to capture 100%
  // of transactions for tracing.
  // We recommend adjusting this value in production
  // Learn more at
  // https://docs.sentry.io/platforms/javascript/configuration/options/#traces-sample-rate
  tracesSampleRate: 1.0,
  // Enable logs to be sent to Sentry
  enableLogs: true,
  // Set profilesSampleRate to 1.0 to profile every transaction.
  // Since profilesSampleRate is relative to tracesSampleRate,
  // the final profiling rate can be computed as tracesSampleRate * profilesSampleRate
  // For example, a tracesSampleRate of 0.5 and profilesSampleRate of 0.5 would
  // result in 25% of transactions being profiled (0.5*0.5=0.25)
  profilesSampleRate: 1.0,
});

// This export will instrument router navigations, and is only relevant if you enable tracing.
// `captureRouterTransitionStart` is available from SDK version 9.12.0 onwards
export const onRouterTransitionStart = Sentry.captureRouterTransitionStart;
```

#### Server-Side Configuration

```javascript
import * as Sentry from "@sentry/nextjs";
Sentry.init({
  dsn: "https://examplePublicKey@o0.ingest.sentry.io/0",
  // Adds request headers and IP for users, for more info visit:
  // https://docs.sentry.io/platforms/javascript/guides/nextjs/configuration/options/#sendDefaultPii
  sendDefaultPii: true,
  // Set tracesSampleRate to 1.0 to capture 100%
  // of transactions for tracing.
  // We recommend adjusting this value in production
  // Learn more at
  // https://docs.sentry.io/platforms/javascript/configuration/options/#traces-sample-rate
  tracesSampleRate: 1.0,
  // Enable logs to be sent to Sentry
  enableLogs: true,
});
```

#### Register Sentry Server-Side SDK Initialization

Create a Next.js Instrumentation file named `instrumentation.(js|ts)` in your project root or inside the `src` folder if you have one. Import your server and edge configurations, making sure that the imports point to your specific files:

```javascript
export async function register() {
  if (process.env.NEXT_RUNTIME === "nodejs") {
    await import("./sentry.server.config");
  }
  if (process.env.NEXT_RUNTIME === "edge") {
    await import("./sentry.edge.config");
  }
}
```

### Go

Grab the Sentry Go SDK:

```bash
go get "github.com/getsentry/sentry-go"
```

Configuration should happen as early as possible in your application's lifecycle.

```text
err := sentry.Init(sentry.ClientOptions{
  Dsn: "https://examplePublicKey@o0.ingest.sentry.io/0",
  // Enable printing of SDK debug messages.
  // Useful when getting started or trying to figure something out.
  Debug: true,
  // Adds request headers and IP for users,
  // visit: https://docs.sentry.io/platforms/go/data-management/data-collected/ for more info
  SendDefaultPII: true,
  EnableTracing: true,
  // Set TracesSampleRate to 1.0 to capture 100%
  // of transactions for tracing.
  TracesSampleRate: 1.0,
})
if err != nil {
  log.Fatalf("sentry.Init: %s", err)
}
// Flush buffered events before the program terminates.
// Set the timeout to the maximum duration the program can afford to wait.
defer sentry.Flush(2 * time.Second)
```

### Ruby

Add the sentry-ruby gem to your Gemfile:

```ruby
gem "sentry-ruby"
```

Configuration should happen as early as possible in your application's lifecycle.

```ruby
require 'sentry-ruby'

Sentry.init do |config|
  config.dsn = 'https://examplePublicKey@o0.ingest.sentry.io/0'

  # get breadcrumbs from logs
  config.breadcrumbs_logger = [:sentry_logger, :http_logger]

  # Add data like request headers and IP for users, if applicable;
  # see https://docs.sentry.io/platforms/ruby/data-management/data-collected/ for more info
  config.send_default_pii = true
  # enable tracing
  # we recommend adjusting this value in production
  config.traces_sample_rate = 1.0
  # Enable logs to be sent to Sentry
  config.enable_logs = true
  # enable profiling
  # this is relative to traces_sample_rate
  config.profiles_sample_rate = 1.0
end
```

### PHP

Install the Sentry SDK using Composer:

```bash
composer require sentry/sentry
```

To use Profiling, you'll also need to install the Excimer extension via PECL:

```bash
pecl install excimer
```

To capture all errors, even the one during the startup of your application, you should initialize the Sentry PHP SDK as soon as possible.

```php
\Sentry\init([
  'dsn' => 'https://examplePublicKey@o0.ingest.sentry.io/0',
  // Add request headers, cookies and IP address,
  // see https://docs.sentry.io/platforms/php/data-management/data-collected/ for more info
  'send_default_pii' => true,
  // Specify a fixed sample rate
  'traces_sample_rate' => 1.0,
  // Enable logs to be sent to Sentry
  'enable_logs' => true,
  // Set a sampling rate for profiling - this is relative to traces_sample_rate
  'profiles_sample_rate' => 1.0,
]);
```

### .NET

Install the NuGet package to add the Sentry dependency:

```shell
dotnet add package Sentry -v 5.16.2
```

To use Profiling, you'll also need to install the Sentry.Profiling package:

```shell
dotnet add package Sentry.Profiling -v 5.16.2
```

To capture all errors, even the one during the startup of your application, you should initialize the Sentry .NET SDK as soon as possible.

```csharp
SentrySdk.Init(options =>
{
    options.Dsn = "https://examplePublicKey@o0.ingest.sentry.io/0";
    options.Debug = true;
    // Adds request URL and headers, IP and name for users, etc.
    options.SendDefaultPii = true;
    // A fixed sample rate of 1.0 - 100% of all transactions are getting sent
    options.TracesSampleRate = 1.0f;
    // A sample rate for profiling - this is relative to TracesSampleRate
    options.ProfilesSampleRate = 1.0f;
});
```

---

*Source: [sentry.io/product/code-coverage/](https://sentry.io/product/code-coverage/)*