chore: add error handling in parseUnits for scientific notation

.changeset/real-turkeys-bathe.md

@@ -0,0 +1,5 @@
+---
+"viem": patch
+---
+
+Added error handling if scientific notation is passed to `parseUnits`.

src/errors/unit.ts

@@ -0,0 +1,14 @@
+import { BaseError } from './base.js'
+
+export type ScientificNotationUnsupportedErrorType =
+  ScientificNotationUnsupportedError & {
+    name: 'ScientificNotationUnsupportedError'
+  }
+export class ScientificNotationUnsupportedError extends BaseError {
+  constructor({ value }: { value: string }) {
+    super(
+      `Scientific notation is not supported for unit parsing (value: \`${value}\`). Please provide a decimal number.`,
+      { name: 'ScientificNotationUnsupportedError' },
+    )
+  }
+}

src/utils/unit/parseUnits.test.ts

@@ -100,3 +100,16 @@ test('decimals < fraction length', () => {
   expect(parseUnits('69.59000000059', 9)).toMatchInlineSnapshot('69590000001n')
   expect(parseUnits('69.59000002359', 9)).toMatchInlineSnapshot('69590000024n')
 })
+
+test('error: scientific notation', () => {
+  expect(() => parseUnits('1.234e5', 3)).toThrowErrorMatchingInlineSnapshot(`
+    [ScientificNotationUnsupportedError: Scientific notation is not supported for unit parsing (value: \`1.234e5\`). Please provide a decimal number.
+
+    Version: viem@x.y.z]
+  `)
+  expect(() => parseUnits('1.234e-5', 3)).toThrowErrorMatchingInlineSnapshot(`
+    [ScientificNotationUnsupportedError: Scientific notation is not supported for unit parsing (value: \`1.234e-5\`). Please provide a decimal number.
+
+    Version: viem@x.y.z]
+  `)
+})

src/utils/unit/parseUnits.ts

@@ -1,3 +1,4 @@
+import { ScientificNotationUnsupportedError } from '../../errors/unit.js'
 import type { ErrorType } from '../../errors/utils.js'
 
 export type ParseUnitsErrorType = ErrorType
@@ -14,6 +15,9 @@ export type ParseUnitsErrorType = ErrorType
  * // 420000000000n
  */
 export function parseUnits(value: string, decimals: number) {
+  if (value.includes('e'))
+    throw new ScientificNotationUnsupportedError({ value })
+
   let [integer, fraction = '0'] = value.split('.')
 
   const negative = integer.startsWith('-')