feat(lint): add rule for indentation multiple

src/rules/indentationMultiple.spec.ts

@@ -0,0 +1,68 @@
+import { LintConfig, Severity } from '../types'
+import { indentationMultiple } from './indentationMultiple'
+
+describe('indentationMultiple', () => {
+  it('should return an empty array when the line is indented by two spaces', () => {
+    const line = "  %put 'hello';"
+    const config = new LintConfig({ indentationMultiple: 2 })
+    expect(indentationMultiple.test(line, 1, config)).toEqual([])
+  })
+
+  it('should return an empty array when the line is indented by a multiple of 2 spaces', () => {
+    const line = "      %put 'hello';"
+    const config = new LintConfig({ indentationMultiple: 2 })
+    expect(indentationMultiple.test(line, 1, config)).toEqual([])
+  })
+
+  it('should return an empty array when the line is not indented', () => {
+    const line = "%put 'hello';"
+    const config = new LintConfig({ indentationMultiple: 2 })
+    expect(indentationMultiple.test(line, 1, config)).toEqual([])
+  })
+
+  it('should return an array with a single diagnostic when the line is indented incorrectly', () => {
+    const line = "   %put 'hello';"
+    const config = new LintConfig({ indentationMultiple: 2 })
+    expect(indentationMultiple.test(line, 1, config)).toEqual([
+      {
+        message: `Line has incorrect indentation - 3 spaces`,
+        lineNumber: 1,
+        startColumnNumber: 1,
+        endColumnNumber: 1,
+        severity: Severity.Warning
+      }
+    ])
+  })
+
+  it('should return an array with a single diagnostic when the line is indented incorrectly', () => {
+    const line = "  %put 'hello';"
+    const config = new LintConfig({ indentationMultiple: 3 })
+    expect(indentationMultiple.test(line, 1, config)).toEqual([
+      {
+        message: `Line has incorrect indentation - 2 spaces`,
+        lineNumber: 1,
+        startColumnNumber: 1,
+        endColumnNumber: 1,
+        severity: Severity.Warning
+      }
+    ])
+  })
+
+  it('should fall back to a default of 2 spaces', () => {
+    const line = " %put 'hello';"
+    expect(indentationMultiple.test(line, 1)).toEqual([
+      {
+        message: `Line has incorrect indentation - 1 space`,
+        lineNumber: 1,
+        startColumnNumber: 1,
+        endColumnNumber: 1,
+        severity: Severity.Warning
+      }
+    ])
+  })
+
+  it('should return an empty array for lines within the default indentation', () => {
+    const line = "  %put 'hello';"
+    expect(indentationMultiple.test(line, 1)).toEqual([])
+  })
+})

src/rules/indentationMultiple.ts

@@ -0,0 +1,37 @@
+import { LintConfig } from '../types'
+import { LineLintRule } from '../types/LintRule'
+import { LintRuleType } from '../types/LintRuleType'
+import { Severity } from '../types/Severity'
+
+const name = 'indentationMultiple'
+const description = 'Ensure indentation by a multiple of the configured number.'
+const message = 'Line has incorrect indentation'
+const test = (value: string, lineNumber: number, config?: LintConfig) => {
+  if (!value.startsWith(' ')) return []
+
+  const indentationMultiple = config?.indentationMultiple || 2
+  const numberOfSpaces = value.search(/\S|$/)
+  if (numberOfSpaces % indentationMultiple === 0) return []
+  return [
+    {
+      message: `${message} - ${numberOfSpaces} ${
+        numberOfSpaces === 1 ? 'space' : 'spaces'
+      }`,
+      lineNumber,
+      startColumnNumber: 1,
+      endColumnNumber: 1,
+      severity: Severity.Warning
+    }
+  ]
+}
+
+/**
+ * Lint rule that checks if a line is indented by a multiple of the configured indentation multiple.
+ */
+export const indentationMultiple: LineLintRule = {
+  type: LintRuleType.Line,
+  name,
+  description,
+  message,
+  test
+}