A library and command-line tool to create a human-readable text summary of the public API of a Dart package. This is highly suitable for tracking the public API footprints and ensuring that API modifications are visible during code reviews (e.g. using diff tests).

[!NOTE] For robust breaking change tracking, you should use dart_apitool.

What Is Summarized

In addition to exported lib/ libraries and declarations, api_summary tracks the pubspec.yaml sections that define a package's external contract with downstream consumers (dev_dependencies are ignored):

• environment: SDK (sdk, flutter) version constraints required to resolve and run the package.
• dependencies: Runtime dependency version constraints for external packages whose declarations or types are referenced or re-exported in the public API (rendered inline on referenced package:... library headers in api.txt, and under dependencies in api.json and api.yaml). Internal-only runtime dependencies that do not appear in the public API are omitted.
• executables: Public command-line executables exposed via dart run or dart install.

Command Line Usage

You can use the command-line tool to generate an API summary for any package containing a pubspec.yaml file.

Installing Globally

Install the executable using dart install:

dart install api_summary

Then run the tool:

api_summary --package-path /path/to/your/package

Or, to run against the package in the current working directory, just run:

api_summary

Running via dart run

Alternatively, you can run the executable from within a package directory if api_summary is a dependency:

dart run api_summary

Options

• -p, --package-path: The path to the package directory to summarize (defaults to the current working directory).
• -f, --format: The output format for the summary (text, json, or yaml). Defaults to text.
• -o, --output: Write the summary to a file path instead of stdout (relative paths resolve relative to --package-path).
• -w, --write: Write the summary to the default golden file (api.txt, api.json, or api.yaml, based on --format) in the package directory.
• -c, --check: Verify that the golden file (api.txt, api.json, or api.yaml) matches the current public API, exiting with code 1 on mismatch.
• -h, --help: Prints usage instructions.

Note: --output, --write, and --check are mutually exclusive.

Programmatic Usage

You can also use this package programmatically inside your Dart projects, such as in automated testing or continuous integration scripts.

Add api_summary to your pubspec.yaml:

dev_dependencies:
  api_summary: ^1.1.0

Basic Example

Call the apiSummary function to generate a package's public API representation:

import 'package:api_summary/api_summary.dart';

void main() async {
  final summary = await apiSummary('/path/to/package');
  print(summary);
}

An executable programmatic example is also available in the example/example.dart file.

Customizing the Summary

Extend the ApiSummaryCustomizer class to customize what is displayed in the API summary. For example, to exclude specific public classes or only display details of certain elements:

import 'package:api_summary/api_summary.dart';
import 'package:analyzer/dart/element/element.dart';

base class MyCustomizer extends ApiSummaryCustomizer {
  @override
  bool shouldShowDetails(Element element, ApiSummaryContext context) {
    // Exclude elements named 'InternalHelper' from details printout
    if (element.name == 'InternalHelper') {
      return false;
    }
    return super.shouldShowDetails(element, context);
  }
}

void main() async {
  final summary = await apiSummary(
    '/path/to/package',
    customizer: MyCustomizer(),
  );
  print(summary);
}

You can also override includeReferencedTypes to transitively include skeleton declarations (containing type hierarchy but no members) of classes, enums, or mixins from other packages and the SDK that are referenced in your public API:

import 'package:api_summary/api_summary.dart';

base class MyCustomizer extends ApiSummaryCustomizer {
  @override
  bool get includeReferencedTypes => true;
}

Golden File / Diff Testing (expectApiSummaryClean)

A recommended practice is to verify in a unit test that your package's public API matches a checked-in api.txt golden file.

First, generate api.txt in your package root:

dart run api_summary --write

Then wire up expectApiSummaryClean as a one-liner in test/api_test.dart:

import 'package:api_summary/api_summary.dart';
import 'package:test/scaffolding.dart';

void main() {
  test('api_summary', expectApiSummaryClean);
}

If a developer introduces a breaking change or adds a new public API element, expectApiSummaryClean fails the test with a compact line diff and instructs them to run dart run api_summary --write to update api.txt.