### Combining Shared Configurations in nyc.config.js

Source: https://github.com/istanbuljs/nyc/blob/main/README.md

An advanced configuration example showing how to merge multiple shared nyc configurations and override specific options. This is useful for creating complex, reusable nyc setups.

```javascript
'use strict';

const babelConfig = require('@istanbuljs/nyc-config-babel');
const hookRunInThisContextConfig = require('@istanbuljs/nyc-config-hook-run-in-this-context');

module.exports = {
  ...babelConfig,
  ...hookRunInThisContextConfig,
  all: true,
  'check-coverage': true
};
```

--------------------------------

### Quick Start with npx

Source: https://github.com/istanbuljs/nyc/blob/main/docs/setup-codecov.md

Execute this command in your CI runner if your npm test does not run nyc and you have npx available.

```shell
npx nyc --reporter=lcov npm test && npx codecov
```

--------------------------------

### Install Coveralls and NYC Dependencies

Source: https://github.com/istanbuljs/nyc/blob/main/docs/setup-coveralls.md

Add coveralls and nyc as development dependencies to your project using npm.

```shell
npm install coveralls nyc --save-dev
```

--------------------------------

### Setup NYC for Self-Coverage

Source: https://github.com/istanbuljs/nyc/blob/main/docs/profiling.md

Link the local development version of NYC globally and generate self-coverage instrumented files. This is the first step in profiling NYC's performance.

```sh
cd /user/dev/nyc
npm link
node ./build-self-coverage
```

--------------------------------

### Install Codecov and NYC Dependencies

Source: https://github.com/istanbuljs/nyc/blob/main/docs/setup-codecov.md

Install the codecov and nyc packages as development dependencies for your project.

```shell
npm install codecov nyc --save-dev
```

--------------------------------

### Setup Test Project to Use Local NYC

Source: https://github.com/istanbuljs/nyc/blob/main/docs/profiling.md

Link the globally linked NYC into the test project's local node_modules. This ensures the test project uses your development version of NYC for profiling.

```sh
cd /user/dev/ava
npm link nyc
```

--------------------------------

### Stream Instrumented Source

Source: https://github.com/istanbuljs/nyc/blob/main/docs/instrument.md

This example demonstrates how to use `nyc instrument` to stream instrumented source code directly to stdout, which can then be piped to another process. This is useful for creating servers that dynamically instrument files on request.

```javascript
app.use((req, res, next) => {
  const myOptions = ""
  const filename = myHelper.getFilename(req)
  const nyc = cp.spawn(`nyc instrument ${myOptions} ${filename}`)
  nyc.stdout.pipe(res)
})
```

--------------------------------

### Run Tests with NYC Coverage

Source: https://github.com/istanbuljs/nyc/blob/main/README.md

Configure npm scripts to run your tests with nyc for coverage reporting. This is a common setup for integrating coverage into your CI/CD pipeline.

```json
{
  "scripts": {
    "test": "mocha",
    "coverage": "nyc npm run test"
  }
}
```

--------------------------------

### Use Latest NYC via npx

Source: https://github.com/istanbuljs/nyc/blob/main/README.md

Execute nyc using npx to always use the latest version without installing it globally. Pinning to a specific major version like 'nyc@latest' is recommended to avoid unexpected updates.

```json
{
  "scripts": {
    "test": "npx nyc@latest mocha"
  }
}
```

--------------------------------

### Configure Include and Exclude Arrays

Source: https://github.com/istanbuljs/nyc/blob/main/README.md

Use 'include' to specify paths for instrumentation and 'exclude' to omit specific files. The 'exclude' array can also contain negated paths to re-include previously excluded files.

```json
{
  "all": true,
  "include": [
    "src/**/*.js"
  ],
  "exclude": [
    "**/*.spec.js"
  ]
}
```

--------------------------------

### Pre-instrument Source Files

Source: https://github.com/istanbuljs/nyc/blob/main/docs/instrument.md

Use this command to create pre-instrumented source code. Specify an input file or directory and an optional output directory. If no output is specified, instrumented code is sent to stdout.

```bash
nyc instrument <input> [output]
```

--------------------------------

### Configure Coverage Thresholds

Source: https://github.com/istanbuljs/nyc/blob/main/README.md

Define minimum coverage percentages for branches, lines, functions, and statements. If 'check-coverage' is true, the build will fail if coverage drops below these thresholds. Set 'per-file' to true for per-file checks.

```json
{
  "branches": 80,
  "lines": 80,
  "functions": 80,
  "statements": 80
}
```

--------------------------------

### Configure NYC Reporters and Runner

Source: https://github.com/istanbuljs/nyc/blob/main/README.md

Run a test runner (e.g., ava) with nyc, specifying multiple reporters for different coverage output formats like lcov and text-summary.

```shell
nyc --reporter=lcov --reporter=text-summary ava
```

--------------------------------

### Run Test Suite and Generate NYC Self-Coverage Report

Source: https://github.com/istanbuljs/nyc/blob/main/docs/profiling.md

Clear existing self-coverage and cache, run the test suite, and then generate a self-coverage report in the NYC directory. This process captures performance data.

```sh
cd /user/dev/nyc
trash ./.self_coverage
cd /user/dev/ava
trash ./.nyc_cache
npm test
cd /user/dev/nyc
npm run report
```

--------------------------------

### Configure npm Scripts for Coverage

Source: https://github.com/istanbuljs/nyc/blob/main/docs/setup-codecov.md

Update your package.json scripts to include testing with nyc and running codecov.

```json
{
   "scripts": {
     "test": "nyc --reporter=lcov mocha",
     "coverage": "codecov"
   }
}
```

--------------------------------

### Combine NYC Reports from Multiple Runs

Source: https://github.com/istanbuljs/nyc/blob/main/README.md

Configure npm scripts to run multiple test suites with nyc and combine their coverage reports. Use the '--no-clean' flag for subsequent runs to accumulate results.

```json
{
  "scripts": {
    "cover": "npm run cover:unit && npm run cover:integration && npm run cover:report",
    "cover:unit": "nyc --silent npm run test:unit",
    "cover:integration": "nyc --silent --no-clean npm run test:integration",
    "cover:report": "nyc report --reporter=lcov --reporter=text"
  }
}
```

--------------------------------

### Extend NYC Configuration with Overrides

Source: https://github.com/istanbuljs/nyc/blob/main/README.md

Define custom nyc configurations by extending a preset (e.g., '@istanbuljs/nyc-config-typescript') and adding specific overrides like enabling 'all' coverage and 'check-coverage'.

```json
{
  "extends": "@istanbuljs/nyc-config-typescript",
  "all": true,
  "check-coverage": true
}
```

--------------------------------

### Configure Travis CI for Coverage Reports

Source: https://github.com/istanbuljs/nyc/blob/main/docs/setup-coveralls.md

Add the 'after_success' hook to your .travis.yml file to automatically run the coverage script after successful test execution.

```yaml
after_success: npm run coverage
```

--------------------------------

### Update package.json Scripts for Coverage

Source: https://github.com/istanbuljs/nyc/blob/main/docs/setup-coveralls.md

Configure the 'test' and 'coverage' scripts in your package.json to run nyc tests and generate coverage reports piped to coveralls.

```json
{
   "scripts": {
     "test": "nyc mocha",
     "coverage": "nyc report --reporter=text-lcov | coveralls"
   }
}
```

--------------------------------

### Customizing File Exclusion in nyc.config.js

Source: https://github.com/istanbuljs/nyc/blob/main/README.md

Configure nyc to exclude platform-specific files based on the operating system. This snippet demonstrates how to dynamically determine which file to exclude and combine it with default exclusions.

```javascript
'use strict';

const defaultExclude = require('@istanbuljs/schema/default-exclude');
const isWindows = require('is-windows');

let platformExclude = [
  isWindows() ? 'lib/posix.js' : 'lib/win32.js'
];

module.exports = {
  exclude: platformExclude.concat(defaultExclude)
};
```

--------------------------------

### Require Additional Modules

Source: https://github.com/istanbuljs/nyc/blob/main/README.md

Use the --require flag to load additional modules in the subprocess collecting coverage. This is particularly useful when working with tools like esm or when using --all with Babel.

```shell
nyc --require esm mocha
```

--------------------------------

### Configure High and Low Watermarks in NYC

Source: https://github.com/istanbuljs/nyc/blob/main/README.md

Specify custom high and low watermarks for coverage reports in nyc's configuration file. This helps in visualizing test coverage levels.

```json
{
  "watermarks": {
    "lines": [80, 95],
    "functions": [80, 95],
    "branches": [80, 95],
    "statements": [80, 95]
  }
}
```

--------------------------------

### Ignore Specific Methods in NYC Configuration

Source: https://github.com/istanbuljs/nyc/blob/main/README.md

Add method names to the 'ignore-class-method' array in your nyc configuration to exclude all instances of these methods from coverage tracking.

```json
{
  "ignore-class-method": ["render"]
}
```

--------------------------------

### Modify Test Script for Direct NYC Usage

Source: https://github.com/istanbuljs/nyc/blob/main/docs/profiling.md

Update the test script in the test project's package.json to use the `nyc` binary directly and disable Tap's version with `--no-cov`. This is necessary when using a globally linked NYC.

```json
{
  "scripts" : {
    "test": "nyc tap --no-cov test/*.js"
  }
}
```

--------------------------------

### Include Files within node_modules

Source: https://github.com/istanbuljs/nyc/blob/main/README.md

Set 'excludeNodeModules' to false to prevent '**/node_modules/**' from being added to the exclude list. This allows for more granular control over which files within node_modules are instrumented, often used in conjunction with specific 'include' paths.

```json
{
  "all": true,
  "include": [
    "lib/**",
    "node_modules/@my-org/**"
  ],
  "exclude": [
    "node_modules/@my-org/something/unwanted.js",
    "**/test/**"
  ],
  "excludeNodeModules": false
}
```

--------------------------------

### Merge NYC Coverage Reports

Source: https://github.com/istanbuljs/nyc/blob/main/README.md

Use the 'nyc merge' command to produce a single raw coverage output file by combining results from multiple test runs. This is useful for external tools that require a unified coverage report.

```json
{
  "scripts": {
    "cover:merge": "npm run cover:unit && npm run cover:integration && nyc merge .nyc_output coverage.json"
  }
}
```

--------------------------------

### Clean NYC Self-Coverage Scripts

Source: https://github.com/istanbuljs/nyc/blob/main/docs/profiling.md

Remove the self-coverage scripts from the NYC directory to revert to using regular files. This is useful when self-coverage is no longer needed for profiling.

```sh
cd /user/dev/nyc
npm run clean
```

=== COMPLETE CONTENT === This response contains all available snippets from this library. No additional content exists. Do not make further requests.