ErrLookup › jestjs/jest
jestjs/jest
Delightful JavaScript Testing. · TypeScript · 789 source files
Analyzed at 8e6d128e4a on 2026-08-10. 138 documented errors.
| Code / Message | Type | Severity | Tags |
|---|---|---|---|
| babel-jest: Babel ignores | exception | error | babel, jest-transform, configuration, monorepo |
| Attempted to display seed but seed value is undefined | exception | error | jest, jest-reporters, configuration, seed, randomize, reporter |
| Cannot find module | exception | error | jest-config, preset, module-resolution, dependency |
| value must be a mock function | exception | error | jest, expect, matcher, spy, mock, type-error, tohavereturned |
| Returning a Promise from "describe" is not supported. Tests… | exception | error | jest-circus, describe, async, synchronous, test-registration |
| any() expects to be passed a constructor function. Please… | validation | error | expect, asymmetric-matcher, typeerror, api-misuse |
| Could not find a "package.json" file in | exception | error | create-jest, initialization, package-json, configuration |
| value must be a mock or spy function | exception | error | jest, expect, matcher, spy, mock, type-error, tohavebeencalled |
| value must be a string or regular expression or class or… | exception | error | jest, expect, matcher, type-error, tothrow, error |
| Tests cannot be nested. Test | validation | error | it, nesting, jasmine, test-structure, api-misuse |
| Crawler retry failed: Original error | exception | error | watchman, filesystem, crawler, configuration, permissions |
| Spies must be created in a before function or a spec | validation | error | spy, jasmine, test-structure, lifecycle, spyon |
| You must provide an array to | validation | error | expect, asymmetric-matcher, typeerror, api-misuse |
| expect.extend: ` ` is not a valid matcher. Must be a… | validation | error | expect, expect-extend, custom-matcher, typeerror |
| Whoops! Two projects resolved to the same config path | exception | error | jest-config, multi-project, duplicate-config, monorepo |
| value must be a number or bigint | validation | error | matcher, type-validation, numeric |
| Duplicated files or mocks. Please check the console for… | exception | error | duplicate, haste, module-collision, typescript, build-artifacts |
| describe does not expect any arguments | validation | error | describe, api-misuse, jasmine, async, validation |
| Invalid first argument. It must be a callback function. | validation | error | beforeeach, hooks, typeerror, jasmine, api-misuse, validation |
| expect.customEqualityTesters: Must be set to an array of… | validation | error | expect, equality-testers, typeerror, api-misuse |
| Failed to start watch mode. | exception | error | watch-mode, filesystem, watchman, parcel-watcher, inotify, configuration |
| value must be a number | exception | error | jest, expect, matcher, type-error, numeric, tobecloseto |
| Could not resolve a module for a custom reporter. Module… | exception | error | jest-config, reporter, module-resolution, dependency |
| Jest: Cannot use configuration as an object without a file… | exception | error | jest-config, readinitialoptions, config-object, rootdir |
| value must be a function | exception | error | jest, expect, matcher, type-error, tothrow, function |
| Jest: Failed to parse the TypeScript config file | exception | error | typescript, config, loader, diagnostic-wrapper |
| Unexpected return from a matcher function. Matcher… | exception | error | expect, custom-matcher, expect-extend, api-misuse |
| Cannot parse as JSON | exception | error | json, package-json, worker, parse-error, configuration |
| seed value must be between `-0x80000000` and `0x7fffffff`… | validation | error | jest-config, seed, randomize, validation, numeric-range |
| Cannot find `global.gc` function. Please run node with… | exception | error | core, open-handles, gc, node-flags, diagnostic |
| Expected is not a String or a RegExp | validation | error | expect, asymmetric-matcher, typeerror, api-misuse |
| Both -- and --watchAll were specified, but cannot be used… | exception | error | jest-cli, cli-args, conflicting-flags, watch, onlychanged |
| Cannot spy on the property because it is not a function… | validation | error | spy, mock, accessor, edge-case |
| Jasmine spies would overwrite the 'and' and 'calls'… | validation | error | spy, jasmine, property-conflict, createspy, api-misuse |
| jest-haste-map: enableSymlinks config option was set, but… | validation | error | configuration, symlinks, watchman, monorepo, validation |
| Cannot merge config in form of callback | exception | error | jest-config, mergeconfig, callback-config, type-error |
| There is malformed json in | exception | error | create-jest, package-json, json-syntax, initialization |
| Jest: `failing` tests are only supported in `jest-circus`. | exception | error | test-runner, jest-circus, jasmine2, api-mismatch, configuration |
| Primitives cannot leak memory. You passed a | validation | error | jest, leak-detector, primitive, memory, type-error |
| : typeof is not a number | validation | error | diff-sequences, input-validation, typeerror, api-misuse |
| haste.enableSymlinks is incompatible with watchman | validation | error | jest-config, haste, watchman, symlinks, validation |
| A "describe" callback must not return a value. | exception | error | jest-circus, describe, return-value, arrow-function |
| jest-haste-map: the `ignorePattern` option must be a RegExp | validation | error | configuration, validation, typescript, regex |
| You must provide an object to | validation | error | expect, asymmetric-matcher, typeerror, api-misuse |
| The --config option requires a JSON string literal, or a… | exception | error | jest-cli, cli-args, config, file-extension, json |
| jest.config.mts requires native TypeScript support. Ensure… | exception | error | typescript, config, node-version, esm, loader |
| Do not import `@jest/globals` outside of the Jest test… | exception | critical | jest-globals, import-error, runtime, configuration |
| value must not be null nor undefined | exception | error | jest, expect, matcher, type-error, tocontain, null-check |
| Shard / requested, but test sequencer in has no shard… | exception | error | jest-core, sharding, test-sequencer, ci, configuration |
| Both --runInBand and --maxWorkers were specified, only one… | exception | error | jest-cli, cli-args, conflicting-flags, runinband, maxworkers |
| : value is not a safe integer | validation | error | diff-sequences, input-validation, rangeerror, numeric |
| Unable to forward JSDOM console output - neither sendTo nor… | exception | error | jest-environment-jsdom, version-compatibility, jsdom, configuration |
| this matcher must not have an expected argument | validation | error | jest, matcher, assertion, api-misuse, expected-argument |
| The --findRelatedTests option requires file paths to be… | exception | error | jest-cli, cli-args, findrelatedtests, precommit, missing-argument |
| Unexpected input | exception | error | memory, config, argument-validation |
| Jest: Got error running | exception | critical | jest-core, global-setup, configuration, lifecycle-hook |
| Missing second argument. It must be a callback function… | validation | error | it, test, api-misuse, jasmine, todo, validation |
| Expected is not a string | validation | error | expect, asymmetric-matcher, typeerror, api-misuse |
| received value must be a promise or a function returning a… | exception | error | expect, resolves, async, promise, assertion |
| Watch plugin configuration error | validation | error | jest-core, watch-mode, watch-plugins, configuration |
| path must not be an empty array | exception | error | jest, expect, matcher, validation, tohaveproperty, path, array |
| Can't find a root directory while resolving a config file… | exception | error | config, paths, filesystem, argument-validation |
| The shard option requires a string in the format of | exception | error | cli, sharding, ci, argument-validation |
| : typeof is not a function | validation | error | diff-sequences, input-validation, typeerror, callbacks |
| Todo must be called with only a description. | validation | error | todo, it, api-misuse, jasmine, validation |
| value must have a length property whose value must be a… | exception | error | jest, expect, matcher, type-error, tohavelength, array |
| Argument passed to callFake should be a function, got | validation | error | spy, callfake, typeerror, jasmine, api-misuse |
| Jest: concurrent test | exception | error | jest, concurrent, async, promise, api-misuse |
| Missing second argument. It must be a callback function. | validation | error | describe, api-misuse, jasmine, validation, test-structure |
| jest: No configuration found for any project. | exception | critical | jest-config, readconfigs, missing-config, bootstrap |
| Custom export conditions specified but they are not an… | exception | error | jest-environment-jsdom, configuration, export-conditions, validation |
| `.each` must be called with an Array or Tagged Template… | exception | error | jest-each, parameterized-tests, validation, type-error |
| The --maxWorkers (-w) option requires a number or string to… | exception | error | jest-cli, cli-args, maxworkers, missing-argument, watch |
| The name ` ` was looked up in the Haste module map. It… | exception | error | jest-haste-map, duplicate-modules, module-resolution, configuration, monorepo |
| Expect takes at most one argument. | validation | error | expect, api-misuse, assertion |
| There was an error while parsing the `--config` argument as… | exception | error | jest-config, config, json-parse, cli |
| ● Multiple configurations found: * | validation | error | config, discovery, validation, multi-config |
| value must be a non-null object | exception | error | jest, expect, matcher, type-error, tomatchobject, object |
| file must export a function at | exception | error | core, global-hooks, config, contract, argument-validation |
| ● Validation Error: Configuration in | validation | error | config, package-json, filesystem, validation |
| Filter did not return a valid test list | exception | error | core, filter, argument-validation, contract |
| : could not find an object to spy upon for () Usage: spyOn(… | validation | error | jest, spyon, mocking, undefined, api-misuse |
| Unexpected numerical input | exception | error | memory, config, argument-validation |
| `.each` must only be called with an Array or Tagged… | exception | error | jest-each, parameterized-tests, validation, api-misuse |
| value must be a non-negative integer | validation | error | matcher, type-validation, integer, spy |
| value must be a string if value is a string | exception | error | jest, expect, matcher, type-error, tocontain, string |
| : has already been spied upon Usage: spyOn( , ) | validation | error | jest, spyon, mocking, duplicate-spy, test-isolation |
| Error: `.each` called with a Tagged Template Literal with… | exception | error | jest-each, parameterized-tests, validation, tagged-template |
| Jest: ' ' is required for the TypeScript configuration… | exception | error | typescript, config, loader, missing-dependency, docblock |
| Expected is not a Number | validation | error | expect, asymmetric-matcher, typeerror, numeric |
| value must be a string or regular expression | exception | error | jest, expect, matcher, type-error, tomatch, regexp |
| Not enough arguments supplied for given headings | exception | error | jest-each, parameterized-tests, validation, tagged-template, data-mismatch |
| Both --onlyFailures and --watchAll were specified, only one… | exception | error | jest-cli, cli-args, conflicting-flags, watch, onlyfailures |
| Ran timers, and there are still more! Assuming we've hit an… | exception | error | jest-fake-timers, legacy-fake-timers, infinite-loop, setinterval, settimeout |
| must be a positive integer | exception | error | jest, expect, matcher, spy, validation, tohavebeennthcalledwith, index |
| Precision is not a Number | validation | error | expect, asymmetric-matcher, typeerror, numeric |
| For a percentage based memory limit a percentageReference… | exception | error | memory, config, argument-validation, worker |
| : property does not exist Usage: spyOn( , ) | validation | error | jest, spyon, mocking, property-accessor, missing-property, api-misuse |
| Invalid second argument | validation | error | describe, api-misuse, typeerror, jasmine, validation |
| path must be a string or array | exception | error | jest, expect, matcher, type-error, tohaveproperty, path |