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Rslint

    no-interpolation-in-snapshots

    Added in v0.8.0

    Configuration

    PresetConfigured Value
    ✅ rstestPlugin.configs.recommended"error"
    rslint.config.ts
    import { defineConfig, rstestPlugin } from '@rslint/core';

export default defineConfig([
  rstestPlugin.configs.recommended,
  {
    rules: {
      'rstest/no-interpolation-in-snapshots': 'error',
    },
  },
]);

    Rule Details

    Disallow string interpolation inside inline snapshots. The expected value of an inline snapshot lives in the source file, and updating snapshots rewrites that literal — so the interpolation is evaluated away and silently lost. Overload dynamic properties with a property matcher instead.

    Examples of incorrect code for this rule:

    import { expect } from '@rstest/core';

expect(something).toMatchInlineSnapshot(
  `Object {
    property: ${interpolated}
  }`,
);

expect(something).toMatchInlineSnapshot(
  { other: expect.any(Number) },
  `Object {
    other: Any<Number>,
    property: ${interpolated}
  }`,
);

expect(errorThrowingFunction).toThrowErrorMatchingInlineSnapshot(
  `${interpolated}`,
);

    Examples of correct code for this rule:

    import { expect } from '@rstest/core';

expect(something).toMatchInlineSnapshot();

expect(something).toMatchInlineSnapshot(
  `Object {
    property: 1
  }`,
);

expect(something).toMatchInlineSnapshot(
  { property: expect.any(Date) },
  `Object {
    property: Any<Date>
  }`,
);

expect(errorThrowingFunction).toThrowErrorMatchingInlineSnapshot();

expect(errorThrowingFunction).toThrowErrorMatchingInlineSnapshot(
  `Error Message`,
);

// Custom messages are not snapshot content, so interpolation is allowed.
expect(errorThrowingFunction).toThrowErrorMatchingInlineSnapshot(
  `Error Message`,
  `case ${caseId}`,
);

expect(something).toMatchInlineSnapshot(
  { property: expect.any(Date) },
  `Object {
    property: Any<Date>
  }`,
  `case ${caseId}`,
);

    Only inline snapshots are checked

    The rule covers toMatchInlineSnapshot and toThrowErrorMatchingInlineSnapshot only. Every other snapshot matcher keeps its expected value outside the source file, so nothing rewrites its arguments and interpolation is harmless:

    • toMatchSnapshot and its Chai-style alias matchSnapshot
    • toThrowErrorMatchingSnapshot
    • toMatchFileSnapshot

    toMatchFileSnapshot deserves a special mention: it has no Jest counterpart, and its first argument is a file path, so interpolating it is the intended usage rather than a mistake.

    // correct — the argument is a path, not a snapshot
await expect(data).toMatchFileSnapshot(`./__snapshots__/${name}.json`);

    Original Documentation