tessl/npm-jest--console
Console utilities for Jest testing framework that provide custom console implementations including BufferedConsole for capturing output, CustomConsole for formatted logging, and NullConsole for suppressing output during tests
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Jest Console
Jest Console provides essential console utilities for the Jest testing framework, enabling developers to control and capture console output during test execution. It offers three main console implementations: BufferedConsole for collecting console output in memory, CustomConsole for providing formatted console output with custom styling, and NullConsole for completely suppressing console output during tests.
Package Information
- Package Name: @jest/console
- Package Type: npm
- Language: TypeScript
- Installation:
npm install @jest/console
Core Imports
import { BufferedConsole, CustomConsole, NullConsole, getConsoleOutput } from "@jest/console";
import type { ConsoleBuffer, LogMessage, LogType, LogEntry } from "@jest/console";For CommonJS:
const { BufferedConsole, CustomConsole, NullConsole, getConsoleOutput } = require("@jest/console");Basic Usage
import { BufferedConsole, CustomConsole, NullConsole } from "@jest/console";
// BufferedConsole - capture output in memory
const bufferedConsole = new BufferedConsole();
bufferedConsole.log("Hello, World!");
bufferedConsole.error("Something went wrong");
const buffer = bufferedConsole.getBuffer();
// buffer contains array of log entries with messages, types, and stack traces
// CustomConsole - formatted real-time output
import { WriteStream } from "tty";
const customConsole = new CustomConsole(process.stdout, process.stderr);
customConsole.log("Formatted output");
// NullConsole - suppress all output
const nullConsole = new NullConsole();
nullConsole.log("This will not appear anywhere");Architecture
Jest Console is built around several key components:
- BufferedConsole: Extends Node.js Console to capture all output in memory as structured log entries
- CustomConsole: Extends Node.js Console to provide formatted output to custom streams with optional message formatting
- NullConsole: Extends CustomConsole to suppress all console output completely
- Output Formatting: Utilities for converting captured console logs into formatted, styled output strings
Capabilities
Buffered Console Implementation
Console implementation that captures all output in memory for later retrieval and analysis, ideal for testing scenarios where you need to verify console output.
class BufferedConsole extends Console {
constructor();
getBuffer(): ConsoleBuffer | undefined;
static write(
buffer: ConsoleBuffer,
type: LogType,
message: LogMessage,
stackLevel?: number
): ConsoleBuffer;
}Custom Console Implementation
Console implementation that outputs to custom streams with optional formatting, perfect for providing styled console output in custom environments.
type Formatter = (type: LogType, message: LogMessage) => string;
class CustomConsole extends Console {
constructor(
stdout: WriteStream,
stderr: WriteStream,
formatBuffer?: Formatter
);
getBuffer(): undefined;
}Null Console Implementation
Console implementation that suppresses all output, useful for completely silencing console output during test execution.
class NullConsole extends CustomConsole {
// All console methods are no-ops
}Console Output Formatting
Utility function for formatting console buffer entries into readable string output with proper styling and stack traces.
function getConsoleOutput(
buffer: ConsoleBuffer,
config: StackTraceConfig,
globalConfig: Config.GlobalConfig
): string;Types
type LogMessage = string;
type LogType =
| 'assert'
| 'count'
| 'debug'
| 'dir'
| 'dirxml'
| 'error'
| 'group'
| 'groupCollapsed'
| 'info'
| 'log'
| 'time'
| 'warn';
interface LogEntry {
message: LogMessage;
origin: string;
type: LogType;
}
type ConsoleBuffer = Array<LogEntry>;
// From Node.js util module
interface InspectOptions {
showHidden?: boolean;
depth?: number | null;
colors?: boolean;
customInspect?: boolean;
showProxy?: boolean;
maxArrayLength?: number | null;
maxStringLength?: number | null;
breakLength?: number;
compact?: boolean | number;
sorted?: boolean | ((a: string, b: string) => number);
getters?: boolean | 'get' | 'set';
}
// From Node.js tty module
interface WriteStream extends NodeJS.WriteStream {
isTTY: boolean;
columns: number;
rows: number;
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