diff --git a/lib/test.d.ts b/lib/test.d.ts
index 29e794b..69d70d0 100644
--- a/lib/test.d.ts
+++ b/lib/test.d.ts
@@ -1,119 +1,243 @@
 interface TestOptions {
   /**
-   * The number of tests that can be run at the same time. If unspecified, subtests inherit this value from their parent.
-   * Default: 1.
+   * If a number is provided, then that many tests would run in parallel. If
+   * truthy, it would run (number of cpu cores - 1) tests in parallel. For
+   * subtests, it will be Infinity tests in parallel. If falsy, it would only
+   * run one test at a time. If unspecified, subtests inherit this value from
+   * their parent.
+   *
+   * @default false
    */
   concurrency?: boolean | number;
 
   /**
-   * If truthy, the test is skipped. If a string is provided, that string is displayed in the test results as the reason for skipping the test.
-   * Default: false.
+   * If truthy, and the test context is configured to run only tests, then this
+   * test will be run. Otherwise, the test is skipped.
+   *
+   * @default false
+   */
+  only?: boolean;
+
+  /**
+   * If truthy, the test is skipped. If a string is provided, that string is
+   * displayed in the test results as the reason for skipping the test.
+   *
+   * @default false
    */
   skip?: boolean | string;
 
   /**
-   * If truthy, the test marked as TODO. If a string is provided, that string is displayed in the test results as the reason why the test is TODO.
-   * Default: false.
+   * If truthy, the test marked as TODO. If a string is provided, that string is
+   * displayed in the test results as the reason why the test is TODO.
+   *
+   * @default false
    */
   todo?: boolean | string;
 
   /**
-   * A number of milliseconds the test will fail after. If unspecified, subtests inherit this value from their parent.
-   * Default: Infinity
+   * A number of milliseconds the test will fail after. If unspecified, subtests
+   * inherit this value from their parent.
+   *
+   * @default Infinity
    */
   timeout?: number;
 
-  /**
-   * Allows aborting an in-progress test
-   */
+  /** Allows aborting an in-progress test */
   signal?: AbortSignal;
 }
 
-type TestFn = (t: TestContext) => any | Promise<any>;
+type TestFn = (t: TestContext, done: (result?: any) => void) => any;
 
 export default test;
 
-export function test(name: string, options: TestOptions, fn: TestFn): void;
-export function test(name: string, fn: TestFn): void;
-export function test(options: TestOptions, fn: TestFn): void;
-export function test(fn: TestFn): void;
+/**
+ * @param name The name of the test, which is displayed when reporting test
+ *   results. Default: The name property of fn, or '<anonymous>' if fn does not
+ *   have a name.
+ * @param options Configuration options for the test.
+ * @param fn The function under test. The first argument to this function is a
+ *   TestContext object. If the test uses callbacks, the callback function is
+ *   passed as the second argument. Default: A no-op function.
+ * @returns A {@link Promise} resolved with `undefined` once the test completes.
+ */
+export function test(
+  name?: string,
+  options?: TestOptions,
+  fn?: TestFn
+): Promise<void>;
+export function test(name: string, fn?: TestFn): Promise<void>;
+export function test(options: TestOptions, fn?: TestFn): Promise<void>;
+export function test(fn: TestFn): Promise<void>;
 
 type SuiteFn = (t: SuiteContext) => void;
 
-export function describe(name: string, options: TestOptions, fn: SuiteFn): void;
-export function describe(name: string, fn: SuiteFn): void;
-export function describe(options: TestOptions, fn: SuiteFn): void;
+/**
+ * @param name The name of the suite, which is displayed when reporting test
+ *   results. Default: The name property of fn, or '<anonymous>' if fn does not
+ *   have a name.
+ * @param options Configuration options for the suite. supports the same options
+ *   as test([name][, options][, fn]).
+ * @param fn The function under suite declaring all subtests and subsuites. The
+ *   first argument to this function is a SuiteContext object. Default: A no-op
+ *   function.
+ * @returns `undefined`
+ */
+export function describe(
+  name?: string,
+  options?: TestOptions,
+  fn?: SuiteFn
+): void;
+export function describe(name: string, fn?: SuiteFn): void;
+export function describe(options: TestOptions, fn?: SuiteFn): void;
 export function describe(fn: SuiteFn): void;
 
-type ItFn = (t: ItContext) => any | Promise<any>;
+type ItFn = (done: (result?: any) => void) => any;
 
-export function it(name: string, options: TestOptions, fn: ItFn): void;
-export function it(name: string, fn: ItFn): void;
-export function it(options: TestOptions, fn: ItFn): void;
+/**
+ * @param name The name of the test, which is displayed when reporting test
+ *   results. Default: The name property of fn, or '<anonymous>' if fn does not
+ *   have a name.
+ * @param options Configuration options for the suite. supports the same options
+ *   as test([name][, options][, fn]).
+ * @param fn The function under test. If the test uses callbacks, the callback
+ *   function is passed as an argument. Default: A no-op function.
+ * @returns `undefined`
+ */
+export function it(name?: string, options?: TestOptions, fn?: ItFn): void;
+export function it(name: string, fn?: ItFn): void;
+export function it(options: TestOptions, fn?: ItFn): void;
 export function it(fn: ItFn): void;
 
+type HookFn = (done: (result?: any) => void) => any;
+
+/**
+ * This function is used to create a hook running before running a suite.
+ *
+ * @param fn The hook function. If the hook uses callbacks, the callback
+ *   function is passed as the second argument. Default: A no-op function.
+ * @param options Configuration options for the hook.
+ */
+export function before(fn?: HookFn, options?: HookOptions): void;
+
+/**
+ * This function is used to create a hook running after running a suite.
+ *
+ * @param fn The hook function. If the hook uses callbacks, the callback
+ *   function is passed as the second argument. Default: A no-op function.
+ * @param options Configuration options for the hook.
+ */
+export function after(fn?: HookFn, options?: HookOptions): void;
+
+/**
+ * This function is used to create a hook running before each subtest of the
+ * current suite.
+ *
+ * @param fn The hook function. If the hook uses callbacks, the callback
+ *   function is passed as the second argument. Default: A no-op function.
+ * @param options Configuration options for the hook.
+ */
+export function beforeEach(fn?: HookFn, options?: HookOptions): void;
+
 /**
- * An instance of TestContext is passed to each test function in order to interact with the test runner.
- * However, the TestContext constructor is not exposed as part of the API.
+ * This function is used to create a hook running after each subtest of the
+ * current test.
+ *
+ * @param fn The hook function. If the hook uses callbacks, the callback
+ *   function is passed as the second argument. Default: A no-op function.
+ * @param options Configuration options for the hook.
+ */
+export function afterEach(fn?: HookFn, options?: HookOptions): void;
+
+/**
+ * An instance of TestContext is passed to each test function in order to
+ * interact with the test runner. However, the TestContext constructor is not
+ * exposed as part of the API.
  */
 declare class TestContext {
   /**
-   * This function is used to create subtests under the current test. This function behaves in the same fashion as the top level test() function.
+   * This function is used to create a hook running before each subtest of the
+   * current test.
    */
-  public test(name: string, options: TestOptions, fn: TestFn): Promise<void>;
-  public test(name: string, fn: TestFn): Promise<void>;
-  public test(fn: TestFn): Promise<void>;
+  public beforeEach: typeof beforeEach;
 
   /**
-   * This function is used to write TAP diagnostics to the output.
-   * Any diagnostic information is included at the end of the test's results. This function does not return a value.
+   * This function is used to create a hook running after each subtest of the
+   * current test.
+   */
+  public afterEach: typeof afterEach;
+
+  /**
+   * This function is used to create subtests under the current test. This
+   * function behaves in the same fashion as the top level test() function.
+   */
+  public test: typeof test;
+
+  /**
+   * This function is used to write TAP diagnostics to the output. Any
+   * diagnostic information is included at the end of the test's results. This
+   * function does not return a value.
    *
    * @param message Message to be displayed as a TAP diagnostic.
    */
   public diagnostic(message: string): void;
 
+  /** The name of the test. */
+  public name: string;
+
   /**
-   * This function causes the test's output to indicate the test as skipped.
-   * If message is provided, it is included in the TAP output.
-   * Calling skip() does not terminate execution of the test function. This function does not return a value.
+   * If `shouldRunOnlyTests` is truthy, the test context will only run tests
+   * that have the `only` option set. Otherwise, all tests are run. If Node.js
+   * was not started with the `--test-only` command-line option, this function
+   * is a no-op.
+   *
+   * @param shouldRunOnlyTests Whether or not to run `only` tests.
+   */
+  public runOnly(shouldRunOnlyTests: boolean): void;
+
+  /**
+   * This function causes the test's output to indicate the test as skipped. If
+   * message is provided, it is included in the TAP output. Calling skip() does
+   * not terminate execution of the test function. This function does not return
+   * a value.
    *
    * @param message Optional skip message to be displayed in TAP output.
    */
   public skip(message?: string): void;
 
   /**
-   * This function adds a TODO directive to the test's output.
-   * If message is provided, it is included in the TAP output.
-   * Calling todo() does not terminate execution of the test function. This function does not return a value.
+   * This function adds a TODO directive to the test's output. If message is
+   * provided, it is included in the TAP output. Calling todo() does not
+   * terminate execution of the test function. This function does not return a
+   * value.
    *
    * @param message Optional TODO message to be displayed in TAP output.
    */
   public todo(message?: string): void;
 
-  /**
-   * Can be used to abort test subtasks when the test has been aborted.
-   */
+  /** Can be used to abort test subtasks when the test has been aborted. */
   public signal: AbortSignal;
 }
 
 /**
- * An instance of SuiteContext is passed to each suite function in order to interact with the test runner.
- * However, the SuiteContext constructor is not exposed as part of the API.
+ * An instance of SuiteContext is passed to each suite function in order to
+ * interact with the test runner. However, the SuiteContext constructor is not
+ * exposed as part of the API.
  */
 declare class SuiteContext {
-  /**
-   * Can be used to abort test subtasks when the test has been aborted.
-   */
+  /** Can be used to abort test subtasks when the test has been aborted. */
   public signal: AbortSignal;
 }
 
-/**
- * An instance of ItContext is passed to each suite function in order to interact with the test runner.
- * However, the ItContext constructor is not exposed as part of the API.
- */
-declare class ItContext {
+/** Configuration options for hooks. */
+interface HookOptions {
+  /** Allows aborting an in-progress hook. */
+  signal?: AbortSignal;
+
   /**
-   * Can be used to abort test subtasks when the test has been aborted.
+   * A number of milliseconds the hook will fail after. If unspecified, subtests
+   * inherit this value from their parent.
+   *
+   * @default Infinity
    */
-  public signal: AbortSignal;
+  timeout?: number;
 }