test(no-useless-children-snippet): added tests for the rule

Author: marekdedic

packages/eslint-plugin-svelte/tests/fixtures/rules/no-useless-children-snippet/invalid/children-snippet01-errors.yaml

@@ -0,0 +1,4 @@
+- message: Found an unnecessary children snippet.
+  line: 2
+  column: 3
+  suggestions: null

packages/eslint-plugin-svelte/tests/fixtures/rules/no-useless-children-snippet/invalid/children-snippet01-input.svelte

@@ -0,0 +1,5 @@
+<Foo>
+  {#snippet children()}
+    Hello
+  {/snippet}
+</Foo>

packages/eslint-plugin-svelte/tests/fixtures/rules/no-useless-children-snippet/valid/implicit-snippet01-input.svelte

@@ -0,0 +1,3 @@
+<Foo>
+  Hello
+</Foo>

packages/eslint-plugin-svelte/tests/fixtures/rules/no-useless-children-snippet/valid/named-snippet01-input.svelte

@@ -0,0 +1,5 @@
+<Foo>
+  {#snippet bar()}
+    Hello
+  {/snippet}
+</Foo>

packages/eslint-plugin-svelte/tests/fixtures/rules/no-useless-children-snippet/valid/snippet-with-params01-input.svelte

@@ -0,0 +1,5 @@
+<Foo>
+  {#snippet children(val)}
+    Hello {val}
+  {/snippet}
+</Foo>

packages/eslint-plugin-svelte/tests/src/rules/no-useless-children-snippet.ts

@@ -0,0 +1,12 @@
+import { RuleTester } from '../../utils/eslint-compat';
+import rule from '../../../src/rules/no-useless-children-snippet';
+import { loadTestCases } from '../../utils/utils';
+
+const tester = new RuleTester({
+	languageOptions: {
+		ecmaVersion: 2020,
+		sourceType: 'module'
+	}
+});
+
+tester.run('no-useless-children-snippet', rule as any, loadTestCases('no-useless-children-snippet'));