[Fix] export: false positive for typescript namespace merging

[magarcia]

Fixes #1964

Fixes false positives like this:

export class Foo { }
export namespace Foo { }

export function Foo() { }
export namespace Foo { }

export enum Foo { }
export namespace Foo { }

[codecov]

Codecov Report

Merging #2375 (3603428) into main (41d4500) will increase coverage by 0.02%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main    #2375      +/-   ##
==========================================
+ Coverage   95.00%   95.03%   +0.02%     
==========================================
  Files          66       66              
  Lines        2703     2718      +15     
  Branches      901      913      +12     
==========================================
+ Hits         2568     2583      +15     
  Misses        135      135              

Impacted Files	Coverage Δ
src/rules/export.js	100.00% <100.00%> (ø)

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[ljharb]

Looks like you may need to skip the tests in older eslint versions, or on the older TS parser.

[magarcia]

Looks like you may need to skip the tests in older eslint versions, or on the older TS parser.

Sure 😄 I'm not sure how yet. Do you have an example of how to do that?

BTW: I'm setting it as a draft. After a walk/break 😅 , I realized that this fix won't work properly for:

export class Foo { }
export class Foo { }
export namespace Foo { }

I'll have a second look at it tomorrow, it's already quite late in my timezone.

[ljharb]

Here's an example:

eslint-plugin-import/tests/src/rules/no-commonjs.js

Lines 71 to 96 in 6c957e7

	...(semver.satisfies(eslintPkg.version, '< 4.0.0') ? [] : [
	{ code: 'var x = require("x")', output: 'var x = require("x")', errors: [ { message: IMPORT_MESSAGE }] },
	{ code: 'x = require("x")', output: 'x = require("x")', errors: [ { message: IMPORT_MESSAGE }] },
	{ code: 'require("x")', output: 'require("x")', errors: [ { message: IMPORT_MESSAGE }] },
	{ code: 'require(`x`)',
	parserOptions: { ecmaVersion: 2015 },
	output: 'require(`x`)',
	errors: [ { message: IMPORT_MESSAGE }],
	},
	{ code: 'if (typeof window !== "undefined") require("x")',
	options: [{ allowConditionalRequire: false }],
	output: 'if (typeof window !== "undefined") require("x")',
	errors: [ { message: IMPORT_MESSAGE }],
	},
	{ code: 'if (typeof window !== "undefined") { require("x") }',
	options: [{ allowConditionalRequire: false }],
	output: 'if (typeof window !== "undefined") { require("x") }',
	errors: [ { message: IMPORT_MESSAGE }],
	},
	{ code: 'try { require("x") } catch (error) {}',
	options: [{ allowConditionalRequire: false }],
	output: 'try { require("x") } catch (error) {}',
	errors: [ { message: IMPORT_MESSAGE }],
	},
	]),