feat: wpi no-unnecessary-condition

Author: ota-meshi

.eslintignore

@@ -11,6 +11,7 @@
 /tests/fixtures/rules/valid-compile/valid/babel
 /tests/fixtures/rules/valid-compile/valid/ts
 /tests/fixtures/rules/prefer-style-directive
+/tests/fixtures/rules/@typescript-eslint
 /.svelte-kit
 /svelte.config-dist.js
 /build

README.md

@@ -322,10 +322,11 @@ These rules relate to style guidelines, and are therefore quite subjective:
 
 ## Extension Rules
 
-These rules extend the rules provided by ESLint itself to work well in Svelte:
+These rules extend the rules provided by ESLint itself, or other plugins to work well in Svelte:
 
 | Rule ID | Description |    |
 |:--------|:------------|:---|
+| [svelte/@typescript-eslint/no-unnecessary-condition](https://ota-meshi.github.io/eslint-plugin-svelte/rules/@typescript-eslint/no-unnecessary-condition/) | disallow conditionals where the type is always truthy or always falsy | :wrench: |
 | [svelte/no-inner-declarations](https://ota-meshi.github.io/eslint-plugin-svelte/rules/no-inner-declarations/) | disallow variable or `function` declarations in nested blocks | :star: |
 | [svelte/no-trailing-spaces](https://ota-meshi.github.io/eslint-plugin-svelte/rules/no-trailing-spaces/) | disallow trailing whitespace at the end of lines | :wrench: |
 

docs/rules.md

@@ -75,10 +75,11 @@ These rules relate to style guidelines, and are therefore quite subjective:
 
 ## Extension Rules
 
-These rules extend the rules provided by ESLint itself to work well in Svelte:
+These rules extend the rules provided by ESLint itself, or other plugins to work well in Svelte:
 
 | Rule ID | Description |    |
 |:--------|:------------|:---|
+| [svelte/@typescript-eslint/no-unnecessary-condition](./rules/@typescript-eslint/no-unnecessary-condition.md) | disallow conditionals where the type is always truthy or always falsy | :wrench: |
 | [svelte/no-inner-declarations](./rules/no-inner-declarations.md) | disallow variable or `function` declarations in nested blocks | :star: |
 | [svelte/no-trailing-spaces](./rules/no-trailing-spaces.md) | disallow trailing whitespace at the end of lines | :wrench: |
 

docs/rules/@typescript-eslint/no-unnecessary-condition.md

@@ -0,0 +1,57 @@
+---
+pageClass: "rule-details"
+sidebarDepth: 0
+title: "svelte/@typescript-eslint/no-unnecessary-condition"
+description: "disallow conditionals where the type is always truthy or always falsy"
+---
+
+# svelte/@typescript-eslint/no-unnecessary-condition
+
+> disallow conditionals where the type is always truthy or always falsy
+
+- :exclamation: <badge text="This rule has not been released yet." vertical="middle" type="error"> **_This rule has not been released yet._** </badge>
+- :wrench: The `--fix` option on the [command line](https://eslint.org/docs/user-guide/command-line-interface#fixing-problems) can automatically fix some of the problems reported by this rule.
+
+## :book: Rule Details
+
+This rule reports ???.
+
+<ESLintCodeBlock fix>
+
+<!--eslint-skip-->
+
+```svelte
+<script>
+  /* eslint svelte/@typescript-eslint/no-unnecessary-condition: "error" */
+</script>
+
+<!-- ✓ GOOD -->
+
+<!-- ✗ BAD -->
+
+```
+
+</ESLintCodeBlock>
+
+## :wrench: Options
+
+```json
+{
+  "svelte/@typescript-eslint/no-unnecessary-condition": ["error", {
+   
+  }]
+}
+```
+
+- 
+
+## :books: Further Reading
+
+-
+
+## :mag: Implementation
+
+- [Rule source](https://github.com/ota-meshi/eslint-plugin-svelte/blob/main/src/rules/@typescript-eslint/no-unnecessary-condition.ts)
+- [Test source](https://github.com/ota-meshi/eslint-plugin-svelte/blob/main/tests/src/rules/@typescript-eslint/no-unnecessary-condition.ts)
+
+<sup>Taken with ❤️ [from @typescript-eslint/eslint-plugin](https://typescript-eslint.io/rules/no-unnecessary-condition/)</sup>