feat(ui): show diff in report panel (fix #2406) (#2423)

* feat(ui): show diff on report panel

* refactor: add better type guard

* refactor: move diff to utils

* chore: move utils to ui package

Co-authored-by: Vladimir Sheremet <sleuths.slews0s@icloud.com>

packages/ui/client/components/views/ViewReport.vue

@@ -1,6 +1,7 @@
 <script setup lang="ts">
+import { unifiedDiff } from '../../composables/diff'
 import { openInEditor, shouldOpenInEditor } from '../../composables/error'
-import type { File, ParsedStack, Suite, Task } from '#types'
+import type { ErrorWithDiff, File, ParsedStack, Suite, Task } from '#types'
 import { config } from '~/composables/client'
 import { isDark } from '~/composables/dark'
 import { createAnsiToHtmlFilter } from '~/composables/error'
@@ -94,6 +95,18 @@ function line(stack: ParsedStack) {
 function column(stack: ParsedStack) {
   return stack.sourcePos?.column ?? stack.column
 }
+
+interface Diff { error: NonNullable<Pick<ErrorWithDiff, 'expected' | 'actual'>> }
+type ResultWithDiff = Task['result'] & Diff
+function isDiffShowable(result?: Task['result']): result is ResultWithDiff {
+  return result && result?.error?.expected && result?.error?.actual
+}
+
+function diff(result: ResultWithDiff): string {
+  return unifiedDiff(result.error.expected, result.error.actual, {
+    outputTruncateLength: 80,
+  })
+}
 </script>
 
 <template>
@@ -125,6 +138,9 @@ function column(stack: ParsedStack) {
                 @click.passive="openInEditor(stack.file, line(stack), column(stack))"
               />
             </div>
+            <pre v-if="isDiffShowable(task.result)">
+              {{ `\n${diff(task.result)}` }}
+            </pre>
           </div>
         </div>
       </div>

packages/ui/client/composables/diff.ts

@@ -0,0 +1,96 @@
+import * as diff from 'diff'
+
+export interface DiffOptions {
+  outputTruncateLength?: number
+  outputDiffLines?: number
+  showLegend?: boolean
+}
+
+function formatLine(line: string, maxWidth: number) {
+  return line.slice(0, maxWidth) + (line.length > maxWidth ? '…' : '')
+}
+
+export function unifiedDiff(actual: string, expected: string, options: DiffOptions = {}) {
+  if (actual === expected)
+    return ''
+
+  const { outputTruncateLength = 80, outputDiffLines, showLegend = true } = options
+
+  const indent = '  '
+  const diffLimit = outputDiffLines || 15
+
+  const counts = {
+    '+': 0,
+    '-': 0,
+  }
+  let previousState: '-' | '+' | null = null
+  let previousCount = 0
+  function preprocess(line: string) {
+    if (!line || line.match(/\\ No newline/))
+      return
+
+    const char = line[0] as '+' | '-'
+    if ('-+'.includes(char)) {
+      if (previousState !== char) {
+        previousState = char
+        previousCount = 0
+      }
+      previousCount++
+      counts[char]++
+      if (previousCount === diffLimit)
+        return `${char} ...`
+      else if (previousCount > diffLimit)
+        return
+    }
+    return line
+  }
+
+  const msg = diff.createPatch('string', expected, actual)
+  const lines = msg.split('\n').slice(5).map(preprocess).filter(Boolean) as string[]
+  const isCompact = counts['+'] === 1 && counts['-'] === 1 && lines.length === 2
+
+  let formatted = lines.map((line: string) => {
+    line = line.replace(/\\"/g, '"')
+    if (line[0] === '-') {
+      line = formatLine(line.slice(1), outputTruncateLength)
+      if (isCompact)
+        return line
+      return `- ${formatLine(line, outputTruncateLength)}`
+    }
+    if (line[0] === '+') {
+      line = formatLine(line.slice(1), outputTruncateLength)
+      if (isCompact)
+        return line
+      return `+ ${formatLine(line, outputTruncateLength)}`
+    }
+    if (line.match(/@@/))
+      return '--'
+    return ` ${line}`
+  })
+
+  if (showLegend) {
+    // Compact mode
+    if (isCompact) {
+      formatted = [
+        `- Expected   ${formatted[0]}`,
+        `+ Received   ${formatted[1]}`,
+      ]
+    }
+    else {
+      if (formatted[0].includes('"'))
+        formatted[0] = formatted[0].replace('"', '')
+
+      const last = formatted.length - 1
+      if (formatted[last].endsWith('"'))
+        formatted[last] = formatted[last].slice(0, formatted[last].length - 1)
+
+      formatted.unshift(
+        `- Expected  - ${counts['-']}`,
+        `+ Received  + ${counts['+']}`,
+        '',
+      )
+    }
+  }
+
+  return formatted.map(i => indent + i).join('\n')
+}

packages/ui/package.json

@@ -55,6 +55,7 @@
     "codemirror-theme-vars": "^0.1.1",
     "cypress": "^11.0.1",
     "d3-graph-controller": "^2.3.22",
+    "diff": "^5.1.0",
     "flatted": "^3.2.7",
     "floating-vue": "^2.0.0-y.0",
     "picocolors": "^1.0.0",

packages/vitest/src/integrations/chai/jest-expect.ts

@@ -5,7 +5,7 @@ import { isMockFunction } from '../spy'
 import { addSerializer } from '../snapshot/port/plugins'
 import type { Constructable, Test } from '../../types'
 import { assertTypes } from '../../utils'
-import { unifiedDiff } from '../../node/diff'
+import { unifiedDiff } from '../../utils/diff'
 import type { ChaiPlugin, MatcherState } from '../../types/chai'
 import { arrayBufferEquality, generateToBeMessage, iterableEquality, equals as jestEquals, sparseArrayEquality, subsetEquality, typeEquality } from './jest-utils'
 import type { AsymmetricMatcher } from './jest-asymmetric-matchers'

packages/vitest/src/integrations/chai/jest-matcher-utils.ts

@@ -4,7 +4,7 @@
 import c from 'picocolors'
 import type { PrettyFormatOptions } from 'pretty-format'
 import { format as prettyFormat, plugins as prettyFormatPlugins } from 'pretty-format'
-import { unifiedDiff } from '../../node/diff'
+import { unifiedDiff } from '../../utils/diff'
 import type { DiffOptions, MatcherHintOptions } from '../../types/matcher-utils'
 
 export const EXPECTED_COLOR = c.green

packages/vitest/src/node/error.ts

@@ -8,8 +8,8 @@ import { lineSplitRE, parseStacktrace, posToNumber } from '../utils/source-map'
 import { F_POINTER } from '../utils/figures'
 import { stringify } from '../integrations/chai/jest-matcher-utils'
 import { TypeCheckError } from '../typecheck/typechecker'
+import { type DiffOptions, unifiedDiff } from '../utils/diff'
 import type { Vitest } from './core'
-import { type DiffOptions, unifiedDiff } from './diff'
 import { divider } from './reporters/renderers/utils'
 import type { Logger } from './logger'