🔍 Add unnecessary-mantissa and accompanying tests

docs/rules/unnecessary-mantissa.md

@@ -0,0 +1,25 @@
+# Unnecessary Mantissa
+
+Rule `unnecessary-mantissa` will enforce that trailing decimal points should be removed if they are unnecessary (e.g. removing `.0` from `4.0`).
+
+## Examples
+
+When enabled, the following are allowed:
+
+```scss
+$margin-size: 4.7px;
+
+.foo {
+    border-size: 4.3px 2% .8rem 9ex;
+}
+```
+
+When enabled, the following are disallowed:
+
+```scss
+$margin-size: 4.0px;
+
+.foo {
+    border-size: 10.0px 2.0% .0rem 9.0ex;
+}
+```

lib/config/sass-lint.yml

@@ -36,6 +36,7 @@ rules:
   no-vendor-prefixes: 1
   no-warn: 1
   property-units: 0
+  unnecessary-mantissa: 1
 
   # Nesting
   force-attribute-nesting: 1

lib/rules/unnecessary-mantissa.js

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+'use strict';
+
+var helpers = require('../helpers');
+
+var hasUnnecessaryMantissa = function (mantissa) {
+  return !mantissa.match(/[^0]/);
+};
+
+module.exports = {
+  'name': 'unnecessary-mantissa',
+  'defaults': { },
+  'detect': function (ast, parser) {
+    var result = [];
+
+    ast.traverseByType('number', function (item) {
+      var match = item.content.match(/(\d*)\.(\d+)/);
+      if (match && hasUnnecessaryMantissa(match[2])) {
+        // if the number was written without an integer
+        // (e.g. '.0'), it needs to be replaced with 0
+        var correction = match[1] || '0';
+        result = helpers.addUnique(result, {
+          'ruleId': parser.rule.name,
+          'severity': parser.severity,
+          'line': item.end.line,
+          'column': item.end.column,
+          // TODO: include unit in result?
+          'message': '`' + item.content + '` should be written without the mantissa as `' + correction + '`'
+        });
+      }
+    });
+
+    return result;
+  }
+};

tests/rules/unnecessary-mantissa.js

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+'use strict';
+
+var lint = require('./_lint');
+
+//////////////////////////////
+// SCSS syntax tests
+//////////////////////////////
+describe('unnecessary mantissa - scss', function () {
+  var file = lint.file('unnecessary-mantissa.scss');
+
+  it('enforce', function (done) {
+    lint.test(file, {
+      'unnecessary-mantissa': 1
+    }, function (data) {
+      lint.assert.equal(6, data.warningCount);
+      done();
+    });
+  });
+});
+
+//////////////////////////////
+// Sass syntax tests
+//////////////////////////////
+describe('unnecessary mantissa - scss', function () {
+  var file = lint.file('unnecessary-mantissa.sass');
+
+  it('enforce', function (done) {
+    lint.test(file, {
+      'unnecessary-mantissa': 1
+    }, function (data) {
+      lint.assert.equal(6, data.warningCount);
+      done();
+    });
+  });
+});

tests/sass/unnecessary-mantissa.sass

@@ -0,0 +1,28 @@
+.foo
+  width: 50.0%
+  height: 70.2%
+
+.bar
+  padding: 5px 3.0 10.2px 4.0%
+
+.baz
+  line-height: .7em
+  margin-top: .0px
+
+$foo: 4.0px
+$bar: '10.0px'
+$baz: 11.0
+$quux: '12.0'
+
+.foo
+  @if $bar == 10
+    content: 'bar'
+
+  @if $foo == '4.0px'
+    content: 'bar'
+
+  @if $baz == '12.0'
+    content: 'baz'
+
+  @if $quux == 11
+    content: 'quux'

tests/sass/unnecessary-mantissa.scss

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+.foo {
+  width: 50.0%;
+  height: 70.2%;
+}
+
+.bar {
+  padding: 5px 3.0 10.2px 4.0%;
+}
+
+.baz {
+  line-height: .7em;
+  margin-top: .0px;
+}
+
+$foo: 4.0px;
+$bar: '10.0px';
+$baz: 11.0;
+$quux: '12.0';
+
+.foo {
+  @if $bar == 10 {
+    content: 'bar';
+  }
+
+  @if $foo == '4.0px' {
+    content: 'foo';
+  }
+
+  @if $baz == '12.0' {
+    content: 'baz';
+  }
+
+  @if $quux == 11 {
+    content: 'quux';
+  }
+}