feat: add no-trailing-zeros rule (#236)

* feat: add `no-trailing-zeros` rule

* docs: add `no-trailing-zeros` doc

* chore: lint

* chore: remove unused schema

* fix: test

* docs: fix

* fix: revert to fix tests temporarily

* Revert "fix: revert to fix tests temporarily"

This reverts commit 9582fd1.

* Create sixty-cougars-ring.md

* add more tests & update docs

---------

Co-authored-by: Yosuke Ota <otameshiyo23@gmail.com>

.changeset/sixty-cougars-ring.md

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

README.md

@@ -207,6 +207,7 @@ The rules with the following star :star: are included in the config.
 | [yml/no-empty-mapping-value](https://ota-meshi.github.io/eslint-plugin-yml/rules/no-empty-mapping-value.html) | disallow empty mapping values |  | :star: | :star: |
 | [yml/no-empty-sequence-entry](https://ota-meshi.github.io/eslint-plugin-yml/rules/no-empty-sequence-entry.html) | disallow empty sequence entries |  | :star: | :star: |
 | [yml/no-tab-indent](https://ota-meshi.github.io/eslint-plugin-yml/rules/no-tab-indent.html) | disallow tabs for indentation. |  | :star: | :star: |
+| [yml/no-trailing-zeros](https://ota-meshi.github.io/eslint-plugin-yml/rules/no-trailing-zeros.html) | disallow trailing zeros for floats | :wrench: |  |  |
 | [yml/plain-scalar](https://ota-meshi.github.io/eslint-plugin-yml/rules/plain-scalar.html) | require or disallow plain style scalar. | :wrench: |  | :star: |
 | [yml/quotes](https://ota-meshi.github.io/eslint-plugin-yml/rules/quotes.html) | enforce the consistent use of either double, or single quotes | :wrench: |  | :star: |
 | [yml/require-string-key](https://ota-meshi.github.io/eslint-plugin-yml/rules/require-string-key.html) | disallow mapping keys other than strings |  |  |  |

docs/rules/README.md

@@ -26,6 +26,7 @@ The rules with the following star :star: are included in the `plugin:yml/recomme
 | [yml/no-empty-mapping-value](./no-empty-mapping-value.md) | disallow empty mapping values |  | :star: | :star: |
 | [yml/no-empty-sequence-entry](./no-empty-sequence-entry.md) | disallow empty sequence entries |  | :star: | :star: |
 | [yml/no-tab-indent](./no-tab-indent.md) | disallow tabs for indentation. |  | :star: | :star: |
+| [yml/no-trailing-zeros](./no-trailing-zeros.md) | disallow trailing zeros for floats | :wrench: |  |  |
 | [yml/plain-scalar](./plain-scalar.md) | require or disallow plain style scalar. | :wrench: |  | :star: |
 | [yml/quotes](./quotes.md) | enforce the consistent use of either double, or single quotes | :wrench: |  | :star: |
 | [yml/require-string-key](./require-string-key.md) | disallow mapping keys other than strings |  |  |  |

docs/rules/no-trailing-zeros.md

@@ -0,0 +1,43 @@
+---
+pageClass: "rule-details"
+sidebarDepth: 0
+title: "yml/no-trailing-zeros"
+description: "disallow trailing zeros for floats"
+---
+
+# yml/no-trailing-zeros
+
+> disallow trailing zeros for floats
+
+- :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 enforces the removal of unnecessary trailing zeros from floats.
+
+<eslint-code-block fix>
+
+<!-- eslint-skip -->
+
+```yaml
+# eslint yml/no-trailing-zeros: 'error'
+
+# ✓ GOOD
+"GOOD": 1.2
+
+# ✗ BAD
+'BAD': 1.20
+```
+
+</eslint-code-block>
+
+## :wrench: Options
+
+Nothing.
+
+## :mag: Implementation
+
+- [Rule source](https://github.com/ota-meshi/eslint-plugin-yml/blob/master/src/rules/no-trailing-zeros.ts)
+- [Test source](https://github.com/ota-meshi/eslint-plugin-yml/blob/master/tests/src/rules/no-trailing-zeros.ts)
+- [Test fixture sources](https://github.com/ota-meshi/eslint-plugin-yml/tree/master/tests/fixtures/rules/no-trailing-zeros)

src/configs/prettier.ts

@@ -15,6 +15,7 @@ export = {
     "yml/indent": "off",
     "yml/key-spacing": "off",
     "yml/no-multiple-empty-lines": "off",
+    "yml/no-trailing-zeros": "off",
     "yml/quotes": "off",
   },
 };

src/rules/no-trailing-zeros.ts

@@ -0,0 +1,57 @@
+import type { AST } from "yaml-eslint-parser";
+import { createRule } from "../utils";
+
+export default createRule("no-trailing-zeros", {
+  meta: {
+    docs: {
+      description: "disallow trailing zeros for floats",
+      categories: null,
+      extensionRule: false,
+      layout: true,
+    },
+    fixable: "code",
+    schema: [],
+    messages: {
+      wrongZeros: "Trailing zeros are not allowed, fix to `{{fixed}}`.",
+    },
+    type: "layout",
+  },
+  create(context) {
+    if (!context.parserServices.isYAML) {
+      return {};
+    }
+
+    return {
+      YAMLScalar(node: AST.YAMLScalar) {
+        if (node.style !== "plain") {
+          return;
+        } else if (typeof node.value !== "number") {
+          return;
+        } else if (!node.strValue.endsWith("0")) {
+          return;
+        }
+
+        const parts = node.strValue.split(".");
+        if (parts.length !== 2) {
+          return;
+        }
+
+        while (parts[1].endsWith("0")) {
+          parts[1] = parts[1].slice(0, -1);
+        }
+        const fixed = parts[1] ? parts.join(".") : parts[0] || "0";
+
+        context.report({
+          node,
+          messageId: "wrongZeros",
+          data: {
+            fixed,
+          },
+          fix(fixer) {
+            return fixer.replaceText(node, fixed);
+          },
+        });
+      },
+    };
+  },
+});

src/utils/rules.ts

@@ -19,6 +19,7 @@ import noEmptySequenceEntry from "../rules/no-empty-sequence-entry";
 import noIrregularWhitespace from "../rules/no-irregular-whitespace";
 import noMultipleEmptyLines from "../rules/no-multiple-empty-lines";
 import noTabIndent from "../rules/no-tab-indent";
+import noTrailingZeros from "../rules/no-trailing-zeros";
 import plainScalar from "../rules/plain-scalar";
 import quotes from "../rules/quotes";
 import requireStringKey from "../rules/require-string-key";
@@ -48,6 +49,7 @@ export const rules = [
   noIrregularWhitespace,
   noMultipleEmptyLines,
   noTabIndent,
+  noTrailingZeros,
   plainScalar,
   quotes,
   requireStringKey,

tests/fixtures/rules/no-trailing-zeros/invalid/errors.json

@@ -0,0 +1,62 @@
+[
+  {
+    "message": "Trailing zeros are not allowed, fix to `1.2`.",
+    "line": 4,
+    "column": 10
+  },
+  {
+    "message": "Trailing zeros are not allowed, fix to `.2`.",
+    "line": 6,
+    "column": 10
+  },
+  {
+    "message": "Trailing zeros are not allowed, fix to `1`.",
+    "line": 7,
+    "column": 10
+  },
+  {
+    "message": "Trailing zeros are not allowed, fix to `0`.",
+    "line": 8,
+    "column": 10
+  },
+  {
+    "message": "Trailing zeros are not allowed, fix to `+1`.",
+    "line": 9,
+    "column": 10
+  },
+  {
+    "message": "Trailing zeros are not allowed, fix to `-1`.",
+    "line": 10,
+    "column": 10
+  },
+  {
+    "message": "Trailing zeros are not allowed, fix to `1.2`.",
+    "line": 14,
+    "column": 12
+  },
+  {
+    "message": "Trailing zeros are not allowed, fix to `.2`.",
+    "line": 16,
+    "column": 12
+  },
+  {
+    "message": "Trailing zeros are not allowed, fix to `1`.",
+    "line": 17,
+    "column": 12
+  },
+  {
+    "message": "Trailing zeros are not allowed, fix to `0`.",
+    "line": 18,
+    "column": 12
+  },
+  {
+    "message": "Trailing zeros are not allowed, fix to `+1`.",
+    "line": 19,
+    "column": 12
+  },
+  {
+    "message": "Trailing zeros are not allowed, fix to `-1`.",
+    "line": 20,
+    "column": 12
+  }
+]

tests/fixtures/rules/no-trailing-zeros/invalid/input.yml

@@ -0,0 +1,20 @@
+# {"options": []}
+-   {
+      a: 1.23,
+      b: 1.20,
+      c: .23,
+      d: .20,
+      e: 1.0,
+      f: .0,
+      g: +1.0,
+      h: -1.0
+    }
+-
+    - "a": 1.23
+    - "b": 1.20
+    - "c": .23
+    - "d": .20
+    - "e": 1.0
+    - "f": .0
+    - "g": +1.0
+    - "h": -1.0

tests/fixtures/rules/no-trailing-zeros/invalid/output.yml

@@ -0,0 +1,20 @@
+# no-trailing-zeros/invalid/input.yml
+-   {
+      a: 1.23,
+      b: 1.2,
+      c: .23,
+      d: .2,
+      e: 1,
+      f: 0,
+      g: +1,
+      h: -1
+    }
+-
+    - "a": 1.23
+    - "b": 1.2
+    - "c": .23
+    - "d": .2
+    - "e": 1
+    - "f": 0
+    - "g": +1
+    - "h": -1

tests/fixtures/rules/no-trailing-zeros/valid/input.yml

@@ -0,0 +1,20 @@
+# {"options": []}
+-   {
+      a: 1.23,
+      b: "1.20",
+      c: .23,
+      d: .2,
+      e: "1.0",
+      f: ".0",
+      g: "+1.0",
+      h: "-1.0"
+    }
+-
+    - "a": 1.23
+    - "b": "1.20"
+    - "c": .23
+    - "d": .2
+    - "e": "1.0"
+    - "f": ".0"
+    - "g": "+1.0"
+    - "h": "-1.0"

tests/src/rules/no-trailing-zeros.ts

@@ -0,0 +1,16 @@
+import { RuleTester } from "eslint";
+import rule from "../../../src/rules/no-trailing-zeros";
+import { loadTestCases } from "../../utils/utils";
+
+const tester = new RuleTester({
+  parser: require.resolve("yaml-eslint-parser"),
+  parserOptions: {
+    ecmaVersion: 2020,
+  },
+});
+
+tester.run(
+  "no-trailing-zeros",
+  rule as any,
+  loadTestCases("no-trailing-zeros")
+);