feat: add svelte/no-trailing-spaces rule

.changeset/curly-tigers-destroy.md

@@ -0,0 +1,5 @@
+---
+"eslint-plugin-svelte": minor
+---
+
+feat: add `svelte/no-trailing-spaces` rule

docs/rules.md

@@ -79,6 +79,7 @@ These rules extend the rules provided by ESLint itself to work well in Svelte:
 | Rule ID | Description |    |
 |:--------|:------------|:---|
 | [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: |
 
 ## System
 

docs/rules/no-trailing-spaces.md

@@ -0,0 +1,83 @@
+---
+pageClass: "rule-details"
+sidebarDepth: 0
+title: "svelte/no-trailing-spaces"
+description: "disallow trailing whitespace at the end of lines"
+---
+
+# svelte/no-trailing-spaces
+
+> disallow trailing whitespace at the end of lines
+
+- :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 extends the base ESLint's [no-trailing-spaces] rule. The [no-trailing-spaces] rule does not understand HTML comments and will report trailing whitespace in HTML comments when using `ignoreComments` option.
+This rule supports HTML comments generated by [svelte-eslint-parser].
+
+[svelte-eslint-parser]: https://github.com/ota-meshi/svelte-eslint-parser
+
+<ESLintCodeBlock fix>
+
+<!-- prettier-ignore-start -->
+<!--eslint-skip-->
+
+```svelte
+<script>
+  /* eslint svelte/no-trailing-spaces: "error" */
+
+  /* ✓ GOOD */
+  var foo = 0;
+  /* ✗ BAD */
+  var foo = 0;  
+</script>
+
+<!-- ✓ GOOD -->
+<div>
+  Text
+</div>
+
+<!-- ✗ BAD -->
+<div>  
+  Text  
+</div>
+```
+
+<!-- prettier-ignore-end -->
+
+</ESLintCodeBlock>
+
+## :wrench: Options
+
+```jsonc
+{
+  "no-trailing-spaces": "off", // Don't need ESLint's no-trailing-spaces rule, so turn it off.
+  "svelte/no-trailing-spaces": [
+    "error",
+    {
+      "skipBlankLines": false,
+      "ignoreComments": false
+    }
+  ]
+}
+```
+
+- `skipBlankLines` ... If `true`, allows trailing whitespace on empty lines.
+- `ignoreComments` ... If `true`, allows trailing whitespace in comments.
+
+Same as [no-trailing-spaces] rule option. See [here](https://eslint.org/docs/rules/no-trailing-spaces#options) for details.
+
+## :couple: Related rules
+
+- [no-trailing-spaces]
+
+[no-trailing-spaces]: https://eslint.org/docs/rules/no-trailing-spaces
+
+## :mag: Implementation
+
+- [Rule source](https://github.com/ota-meshi/eslint-plugin-svelte/blob/main/src/rules/no-trailing-spaces.ts)
+- [Test source](https://github.com/ota-meshi/eslint-plugin-svelte/blob/main/tests/src/rules/no-trailing-spaces.ts)
+
+<sup>Taken with ❤️ [from ESLint core](https://eslint.org/docs/rules/no-trailing-spaces)</sup>

src/configs/prettier.ts

@@ -14,6 +14,7 @@ export = {
     "svelte/max-attributes-per-line": "off",
     "svelte/mustache-spacing": "off",
     "svelte/no-spaces-around-equal-signs-in-attribute": "off",
+    "svelte/no-trailing-spaces": "off",
     "svelte/shorthand-attribute": "off",
     "svelte/shorthand-directive": "off",
   },

src/rules/no-trailing-spaces.ts

@@ -0,0 +1,104 @@
+import type { AST } from "svelte-eslint-parser"
+import { createRule } from "../utils"
+
+export default createRule("no-trailing-spaces", {
+  meta: {
+    type: "layout",
+    docs: {
+      description: "disallow trailing whitespace at the end of lines",
+      category: "Extension Rules",
+      recommended: false,
+      extensionRule: "no-trailing-spaces",
+      conflictWithPrettier: true,
+    },
+    fixable: "whitespace",
+    schema: [
+      {
+        type: "object",
+        properties: {
+          skipBlankLines: { type: "boolean" },
+          ignoreComments: { type: "boolean" },
+        },
+        additionalProperties: false,
+      },
+    ],
+    messages: {
+      trailingSpace: "Trailing spaces not allowed.",
+    },
+  },
+  create(context) {
+    const options:
+      | { skipBlankLines?: boolean; ignoreComments?: boolean }
+      | undefined = context.options[0]
+    const skipBlankLines = options?.skipBlankLines || false
+    const ignoreComments = options?.ignoreComments || false
+
+    const sourceCode = context.getSourceCode()
+
+    const ignoreLineNumbers = new Set<number>()
+    if (ignoreComments) {
+      for (const { type, loc } of sourceCode.getAllComments()) {
+        const endLine = type === "Block" ? loc.end.line - 1 : loc.end.line
+        for (let i = loc.start.line; i <= endLine; i++) {
+          ignoreLineNumbers.add(i)
+        }
+      }
+    }
+
+    /**
+     * Reports a given location.
+     */
+    function report(loc: AST.SourceLocation) {
+      context.report({
+        loc,
+        messageId: "trailingSpace",
+        fix(fixer) {
+          return fixer.removeRange([
+            sourceCode.getIndexFromLoc(loc.start),
+            sourceCode.getIndexFromLoc(loc.end),
+          ])
+        },
+      })
+    }
+
+    /**
+     * Collects the location of the given node as the ignore line numbers.
+     */
+    function collectIgnoreLineNumbers({ loc }: { loc: AST.SourceLocation }) {
+      const endLine = loc.end.line - 1
+      for (let i = loc.start.line; i <= endLine; i++) {
+        ignoreLineNumbers.add(i)
+      }
+    }
+
+    return {
+      TemplateElement: collectIgnoreLineNumbers,
+      ...(ignoreComments
+        ? {
+            SvelteHTMLComment: collectIgnoreLineNumbers,
+          }
+        : {}),
+      "Program:exit"() {
+        const lines = sourceCode.lines
+        for (let lineIndex = 0; lineIndex < lines.length; lineIndex++) {
+          const line = lines[lineIndex]
+          if (skipBlankLines && !line.trim()) {
+            continue
+          }
+          const lineNumber = lineIndex + 1
+          if (ignoreLineNumbers.has(lineNumber)) {
+            continue
+          }
+          const trimmed = line.trimEnd()
+          if (trimmed === line) {
+            continue
+          }
+          report({
+            start: { line: lineNumber, column: trimmed.length },
+            end: { line: lineNumber, column: line.length },
+          })
+        }
+      },
+    }
+  },
+})

src/utils/rules.ts

@@ -23,6 +23,7 @@ import noShorthandStylePropertyOverrides from "../rules/no-shorthand-style-prope
 import noSpacesAroundEqualSignsInAttribute from "../rules/no-spaces-around-equal-signs-in-attribute"
 import noStoreAsync from "../rules/no-store-async"
 import noTargetBlank from "../rules/no-target-blank"
+import noTrailingSpaces from "../rules/no-trailing-spaces"
 import noUnknownStyleDirectiveProperty from "../rules/no-unknown-style-directive-property"
 import noUnusedSvelteIgnore from "../rules/no-unused-svelte-ignore"
 import noUselessMustaches from "../rules/no-useless-mustaches"
@@ -62,6 +63,7 @@ export const rules = [
   noSpacesAroundEqualSignsInAttribute,
   noStoreAsync,
   noTargetBlank,
+  noTrailingSpaces,
   noUnknownStyleDirectiveProperty,
   noUnusedSvelteIgnore,
   noUselessMustaches,

tests/fixtures/rules/no-trailing-spaces/invalid/ignoreComments/_config.json

@@ -0,0 +1,7 @@
+{
+  "options": [
+    {
+      "ignoreComments": true
+    }
+  ]
+}

tests/fixtures/rules/no-trailing-spaces/invalid/ignoreComments/test01-errors.yaml

@@ -0,0 +1,36 @@
+- message: Trailing spaces not allowed.
+  line: 5
+  column: 2
+  suggestions: null
+- message: Trailing spaces not allowed.
+  line: 9
+  column: 6
+  suggestions: null
+- message: Trailing spaces not allowed.
+  line: 14
+  column: 1
+  suggestions: null
+- message: Trailing spaces not allowed.
+  line: 23
+  column: 12
+  suggestions: null
+- message: Trailing spaces not allowed.
+  line: 26
+  column: 7
+  suggestions: null
+- message: Trailing spaces not allowed.
+  line: 27
+  column: 7
+  suggestions: null
+- message: Trailing spaces not allowed.
+  line: 30
+  column: 7
+  suggestions: null
+- message: Trailing spaces not allowed.
+  line: 33
+  column: 7
+  suggestions: null
+- message: Trailing spaces not allowed.
+  line: 34
+  column: 23
+  suggestions: null

tests/fixtures/rules/no-trailing-spaces/invalid/ignoreComments/test01-input.svelte

@@ -0,0 +1,35 @@
+<!-- prettier-ignore -->
+<script>
+  const str = `
+
+`  
+  // line comment  
+  /**  
+   * block comment  
+   */  
+  /**
+   * block comment2  
+   */ const a = 42
+  // empty line
+
+  // empty line
+</script>
+
+<!--  
+  HTML comment  
+  -->
+
+<!-- prettier-ignore -->
+<span> Text  
+</span>
+<!-- prettier-ignore -->
+<span>  
+  Text  
+</span>
+<!-- prettier-ignore -->
+<span>  
+  Text </span>
+<!-- prettier-ignore -->
+<span>  
+    <span>Text </span>  
+  </span>

tests/fixtures/rules/no-trailing-spaces/invalid/ignoreComments/test01-output.svelte

@@ -0,0 +1,35 @@
+<!-- prettier-ignore -->
+<script>
+  const str = `
+
+`
+  // line comment  
+  /**  
+   * block comment  
+   */
+  /**
+   * block comment2  
+   */ const a = 42
+  // empty line
+
+  // empty line
+</script>
+
+<!--  
+  HTML comment  
+  -->
+
+<!-- prettier-ignore -->
+<span> Text
+</span>
+<!-- prettier-ignore -->
+<span>
+  Text
+</span>
+<!-- prettier-ignore -->
+<span>
+  Text </span>
+<!-- prettier-ignore -->
+<span>
+    <span>Text </span>
+  </span>

tests/fixtures/rules/no-trailing-spaces/invalid/skipBlankLines/_config.json

@@ -0,0 +1,7 @@
+{
+  "options": [
+    {
+      "skipBlankLines": true
+    }
+  ]
+}