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fix(eslint-plugin): [switch-exhaustiveness-check] handle special characters in enum keys #2207

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merged 4 commits into from Jul 10, 2020
Merged

fix(eslint-plugin): [switch-exhaustiveness-check] handle special characters in enum keys #2207

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7076673
fix(eslint-plugin): [switch-exhaustiveness-check] add quotes and box …
karishnu Jun 11, 2020
9c1f8bd
fix(eslint-plugin): [switch-exhaustiveness-check] add test for case w…
karishnu Jun 11, 2020
27fd2d2
fix(eslint-plugin): [switch-exhaustiveness-check] Support non English…
karishnu Jul 8, 2020
5825e4a
fix(eslint-plugin): [switch-exhaustiveness-check] Add tests for new v…
karishnu Jul 8, 2020
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22 changes: 20 additions & 2 deletions packages/eslint-plugin/src/rules/switch-exhaustiveness-check.ts
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Expand Up @@ -42,7 +42,9 @@ export default createRule({
fixer: TSESLint.RuleFixer,
node: TSESTree.SwitchStatement,
missingBranchTypes: Array<ts.Type>,
symbolName?: string,
): TSESLint.RuleFix | null {
const identifierRegex = /^[a-zA-Z_$][0-9a-zA-Z_$]*$/;
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The problem we've got is that a-zA-Z doesn't include all of the "letter-like" characters that are actually allowed in the spec (chinese/japanese/korean/cyrillic/etc characters, accented characters), etc. So for a large number of codebases this regex will actually cause a false match. A false match isn't the end of the world, but it's going to be annoying for non-english speakers.

This is the actual regex of allowed characters within a variable name: https://github.com/estools/esutils/blob/a825f91fd1d1e3a9fff84227cb06c011d8a0b9e8/lib/code.js#L39-L44

It's a mess.

TypeScript needs to parse identifiers itself, and thankfully they export two functions that we can use here: isIdentifierStart and isIdentifierPart.

You can use this function instead to determine if the name requires quoting:

const compilerOptions = service.program.getCompilerOptions();
function requiresQuoting(name: string): boolean {
  if (name.length === 0) {
    return true;
  }
  if (!ts.isIdentifierStart(name.charCodeAt(0), compilerOptions.target)) {
    return true;
  }

  for (let i = 1; i < name.length; i += 1) {
    if (!ts.isIdentifierPart(name.charCodeAt(i), compilerOptions.target)) {
      return true;
    }
  }

  return false;
}

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Thank you! Will make the changes as soon as I can find some time.

const lastCase =
node.cases.length > 0 ? node.cases[node.cases.length - 1] : null;
const caseIndent = lastCase
Expand All @@ -67,7 +69,17 @@ export default createRule({
continue;
}

const caseTest = checker.typeToString(missingBranchType);
const missingBranchName = missingBranchType.getSymbol()?.escapedName;
let caseTest = checker.typeToString(missingBranchType);

if (
symbolName &&
missingBranchName &&
!identifierRegex.test(missingBranchName.toString())
) {
caseTest = `${symbolName}['${missingBranchName}']`;
}

const errorMessage = `Not implemented yet: ${caseTest} case`;

missingCases.push(
Expand Down Expand Up @@ -101,6 +113,7 @@ export default createRule({

function checkSwitchExhaustive(node: TSESTree.SwitchStatement): void {
const discriminantType = getNodeType(node.discriminant);
const symbolName = discriminantType.getSymbol()?.escapedName;

if (discriminantType.isUnion()) {
const unionTypes = unionTypeParts(discriminantType);
Expand Down Expand Up @@ -139,7 +152,12 @@ export default createRule({
{
messageId: 'addMissingCases',
fix(fixer): TSESLint.RuleFix | null {
return fixSwitch(fixer, node, missingBranchTypes);
return fixSwitch(
fixer,
node,
missingBranchTypes,
symbolName?.toString(),
);
},
},
],
Expand Down
37 changes: 37 additions & 0 deletions packages/eslint-plugin/tests/rules/switch-exhaustiveness-check.test.ts
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Expand Up @@ -483,6 +483,43 @@ function test(value: T): number {
case 1: { throw new Error('Not implemented yet: 1 case') }
case 2: { throw new Error('Not implemented yet: 2 case') }
}
}
`.trimRight(),
},
],
},
],
},
{
// keys include special characters
code: `
export enum Enum {
'test-test' = 'test-test',
'test' = 'test',
}

function test(arg: Enum): string {
switch (arg) {
}
}
`.trimRight(),
errors: [
{
messageId: 'switchIsNotExhaustive',
suggestions: [
{
messageId: 'addMissingCases',
output: noFormat`
export enum Enum {
'test-test' = 'test-test',
'test' = 'test',
}

function test(arg: Enum): string {
switch (arg) {
case Enum['test-test']: { throw new Error('Not implemented yet: Enum['test-test'] case') }
case Enum.test: { throw new Error('Not implemented yet: Enum.test case') }
}
}
`.trimRight(),
},
Expand Down