prettier/tests/format/flow/flow-repo/match/patterns.js

// Top level binding with `const`
{
  declare const x: number;

  const out = match (x) {
    const a => a,
  };
  out as number; // OK
  out as empty; // ERROR
}

// Binding doesn't leak to outer scope
{
  declare const x: number;

  const out = match (x) {
    const a => a,
  };

  a; // ERROR: cannot resolve name
}

// Array pattern
{
  declare const x: [number];

  const out = match (x) {
    [const a] => a,
  };
  out as number; // OK
  out as empty; // ERROR
}

// Object pattern
{
  declare const x: {foo: number};

  const out = match (x) {
    {foo: const a} => a,
  };

  out as number; // OK
  out as empty; // ERROR
}

// Object shorthand pattern
{
  declare const x: {foo: number};

  const out = match (x) {
    {const foo} => foo,
  };

  out as number; // OK
  out as empty; // ERROR
}

// Nested patterns
{
  declare const x: {foo: [{bar: number}]};

  const out1 = match (x) {
    {foo: [{bar: const a}]} => a,
    _ => 0,
  };
  out1 as number; // OK
  out1 as empty; // ERROR

  const out2 = match (x) {
    {foo: const a} => a[0].bar,
  };
  out2 as number; // OK
  out2 as empty; // ERROR
}

// Guards
{
  declare const x: {foo: number};
  declare const f: number => boolean;

  const out = match (x) {
    {foo: const n} if (n === 0) => n, // OK
    {foo: const n} if (f(n)) => n, // OK
    {foo: const n} if (n as empty) => n, // ERROR
    _ => 0,
  };
}

// As pattern
{
  declare const x: {foo: [number]};

  const out = match (x) {
    {foo: [1] as n} => n as [number], // OK
    {foo: [1 as n]} => n as number, // OK
    _ => 0,
  };
}
{
  declare const x: {foo: [number]};

  const out = match (x) {
    {foo: [1] as const n} => n as [number], // OK
    {foo: [1 as const n]} => n as number, // OK
    _ => 0,
  };
}
{
  declare const x: {foo: {bar: number}};

  const out = match (x) {
    {foo: {bar: 1}} => 0, // OK
    {foo: {bar: 2} as const a} => 0, // OK
    {foo: {bar: 3 as const a}} => 0, // OK
    {foo: {bar: const a}} => 0, // OK
    _ => 0,
  };
}

// Array rest
{
  declare const x: [1, 2, 3];

  const out1 = match (x) {
    [1, 2, ...const xs] => xs as [3], // OK
    _ => 0,
  };
  const out2 = match (x) {
    [1, ...const xs] => xs as [2, 3], // OK
    _ => 0,
  };
  const out3 = match (x) {
    [...const xs] => xs as [1, 2, 3], // OK
    _ => 0,
  };
}

// Object rest
{
  declare const x: {foo: 1, bar: 2, baz: 3};

  const out1 = match (x) {
    {foo: _, bar: _, ...const xs} => xs as {baz: 3}, // OK
  };
  const out2 = match (x) {
    {bar: _, ...const xs} => xs as {foo: 1, baz: 3}, // OK
  };
  const out3 = match (x) {
    {...const xs} => xs as {foo: 1, bar: 2, baz: 3}, // OK
  };
}

// Identifier, member, literal
{
  declare const A: 3;
  declare const O: {B: 2};
  declare const x: number;

  const out = match (x) {
    0 => 0,
    -1 => 0,
    +1 => 0,
    A => 0,
    O.B => 0,
    _ => 0,
  };
}

// Or pattern
{
  declare const x: number;

  const out = match (x) {
    1 | 2 | 3 => 0,
    _ => 0,
  };
}

// Array pattern applied to array literal
{
  const x = [1, 'foo'] as const;

  const out = match (x) {
    [_, const b] => b as string, // OK
  };
}

// BigInt member pattern
{
  declare const x: string;
  declare const O: {[bigint]: 'foo'};

  const out = match (x) {
    O[1n] => 0, // OK
    _ => 0,
  };
}