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fix(jest-transform): improve runtime errors and warnings #11998

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merged 5 commits into from Nov 1, 2021
Merged

fix(jest-transform): improve runtime errors and warnings #11998

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5821203
fix: better invalid transformer errors
mrazauskas Oct 26, 2021
eed2180
add changelog entry
mrazauskas Oct 26, 2021
b37fe99
more useful errors
mrazauskas Oct 29, 2021
7b32d80
Merge branch 'main'
mrazauskas Oct 29, 2021
f78ee46
add copyright header
mrazauskas Oct 29, 2021
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1 change: 1 addition & 0 deletions CHANGELOG.md
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Expand Up @@ -5,6 +5,7 @@
### Fixes

- `[expect]` Allow again `expect.Matchers` generic with single value ([#11986](https://github.com/facebook/jest/pull/11986))
- `[jest-transform]` Improve the invalid transformer module error message ([#11998](https://github.com/facebook/jest/pull/11998))

### Chore & Maintenance

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22 changes: 18 additions & 4 deletions packages/jest-transform/src/ScriptTransformer.ts
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Expand Up @@ -10,6 +10,7 @@ import * as path from 'path';
import {transformSync as babelTransform} from '@babel/core';
// @ts-expect-error: should just be `require.resolve`, but the tests mess that up
import babelPluginIstanbul from 'babel-plugin-istanbul';
import chalk = require('chalk');
import {fromSource as sourcemapFromSource} from 'convert-source-map';
import stableStringify = require('fast-json-stable-stringify');
import * as fs from 'graceful-fs';
Expand Down Expand Up @@ -250,6 +251,21 @@ class ScriptTransformer {
}

async loadTransformers(): Promise<void> {
const makeInvalidTransformerError = (transformPath: string) =>
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It could also live outside the class, of course. The class is huge, not so easy to decide.

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makes sense to move it outside rather than defining it inline 🙂

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Or even better to move it to separate file together with other runtime errors for this module. Had to think a bit, will do it later.

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that also works - as you say the class is huge and somewhat hard to grok/navigate

chalk.red(
[
chalk.bold('\u25cf Invalid transformer module:'),
` "${slash(
transformPath,
)}" specified in the "transform" object of Jest configuration`,
' must export a `process` or `processAsync` or `createTransformer` function.',
'',
' Code Transformation Documentation:',
' https://jestjs.io/docs/code-transformation',
'',
].join('\n'),
);

await Promise.all(
this._config.transform.map(
async ([, transformPath, transformerConfig]) => {
Expand All @@ -258,7 +274,7 @@ class ScriptTransformer {
);

if (!transformer) {
throw new TypeError('Jest: a transform must export something.');
throw new Error(makeInvalidTransformerError(transformPath));
}
if (typeof transformer.createTransformer === 'function') {
transformer = transformer.createTransformer(transformerConfig);
Expand All @@ -267,9 +283,7 @@ class ScriptTransformer {
typeof transformer.process !== 'function' &&
typeof transformer.processAsync !== 'function'
) {
throw new TypeError(
'Jest: a transform must export a `process` or `processAsync` function.',
);
throw new Error(makeInvalidTransformerError(transformPath));
}
const res = {transformer, transformerConfig};
this._transformCache.set(transformPath, res);
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14 changes: 7 additions & 7 deletions packages/jest-transform/src/__tests__/ScriptTransformer.test.ts
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Expand Up @@ -486,14 +486,14 @@ describe('ScriptTransformer', () => {
await Promise.all([...promisesToReject, ...promisesToResolve]);
});

it('throws an error if neither `process` nor `processAsync is defined', async () => {
it('throws an error if neither `process` nor `processAsync` is defined', async () => {
config = {
...config,
transform: [['\\.js$', 'skipped-required-props-preprocessor', {}]],
};
await expect(() => createScriptTransformer(config)).rejects.toThrow(
'Jest: a transform must export a `process` or `processAsync` function.',
);
await expect(() =>
createScriptTransformer(config),
).rejects.toThrowErrorMatchingSnapshot();
});

it("(in sync mode) throws an error if `process` isn't defined", async () => {
Expand Down Expand Up @@ -537,9 +537,9 @@ describe('ScriptTransformer', () => {
],
],
};
await expect(() => createScriptTransformer(config)).rejects.toThrow(
'Jest: a transform must export a `process` or `processAsync` function.',
);
await expect(() =>
createScriptTransformer(config),
).rejects.toThrowErrorMatchingSnapshot();
});

it("shouldn't throw error without process method. But with correct createTransformer method", async () => {
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20 changes: 20 additions & 0 deletions packages/jest-transform/src/__tests__/__snapshots__/ScriptTransformer.test.ts.snap
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Expand Up @@ -340,6 +340,26 @@ exports[`ScriptTransformer passes expected transform options to getCacheKeyAsync
}
`;

exports[`ScriptTransformer throws an error if createTransformer returns object without \`process\` method 1`] = `
"<red><bold>● Invalid transformer module:</></>
<red> \\"skipped-required-create-transformer-props-preprocessor\\" specified in the \\"transform\\" object of Jest configuration</>
<red> must export a \`process\` or \`processAsync\` or \`createTransformer\` function.</>
<red></>
<red> Code Transformation Documentation:</>
<red> https://jestjs.io/docs/code-transformation</>
<red></>"
`;

exports[`ScriptTransformer throws an error if neither \`process\` nor \`processAsync\` is defined 1`] = `
"<red><bold>● Invalid transformer module:</></>
<red> \\"skipped-required-props-preprocessor\\" specified in the \\"transform\\" object of Jest configuration</>
<red> must export a \`process\` or \`processAsync\` or \`createTransformer\` function.</>
<red></>
<red> Code Transformation Documentation:</>
<red> https://jestjs.io/docs/code-transformation</>
<red></>"
`;

exports[`ScriptTransformer transforms a file async properly 1`] = `
/* istanbul ignore next */
function cov_25u22311x4() {
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