String formatter should escape quotes.

packages/printer/src/formatters/escapeQuotes.ts

@@ -0,0 +1,6 @@
+export function escapeQuotes(str: string, quotes: string) {
+  if (!quotes) return str
+  if (quotes == '"') return JSON.stringify(str)
+  str = str.split(quotes).join('\\' + quotes)
+  return `${quotes}${str}${quotes}`
+}

packages/printer/src/formatters/formatter.ts

@@ -4,6 +4,7 @@ import { isString } from '@logpot/utils'
 import { toColorizer } from '../consoleColor'
 import { PrintContext } from '../printContext'
 import { Printer } from '../printer'
+import { escapeQuotes } from './escapeQuotes'
 import { getText } from './getText'
 
 // A common interface for all formatters.
@@ -41,10 +42,8 @@ export class StringFormatter extends PrimitiveFormatter {
     return isString(value)
   }
   format(value: unknown, ctx: PrintContext) {
-    return getText(
-      ctx,
-      toColorizer(ctx.colorConfig.string)(`${ctx.quotes}${value}${ctx.quotes}`)
-    )
+    const str = escapeQuotes(value as string, ctx.quotes)
+    return getText(ctx, toColorizer(ctx.colorConfig.string)(str))
   }
 }
 
@@ -147,7 +146,7 @@ export class DateFormatter extends PrimitiveFormatter {
       case 'epoch':
         return colorizer(date.getTime().toString())
     }
-    return getText(ctx, colorizer(`${ctx.quotes}${str}${ctx.quotes}`))
+    return getText(ctx, colorizer(escapeQuotes(str, ctx.quotes)))
   }
 }
 

packages/printer/src/formatters/objectFormatter.ts

@@ -3,6 +3,7 @@ import { isEmptyPlainObject, isPlainObject } from '@logpot/utils'
 import { toColorizer } from '../consoleColor'
 import { PrintContext } from '../printContext'
 import { Printer } from '../printer'
+import { escapeQuotes } from './escapeQuotes'
 import { IFormatter } from './formatter'
 import { getText } from './getText'
 import { ObjectFormatterConfig } from './objectFormatterConfig'
@@ -84,7 +85,7 @@ export class ObjectFormatter implements IFormatter {
     printer: Printer
   ): string {
     const coloredKey = toColorizer(ctx.colorConfig.key)(
-      `${ctx.quotes}${key}${ctx.quotes}`
+      escapeQuotes(key, ctx.quotes)
     )
 
     let indent = ctx.indent

packages/printer/src/formatters/stringFormatter.test.ts

@@ -0,0 +1,50 @@
+import { describe, expect, it } from 'vitest'
+
+import { colorlessConfig } from '../colorConfig'
+import { PrintContext } from '../printContext'
+import { StringFormatter } from './formatter'
+
+const makeCtx = (
+  overrides: Partial<Pick<PrintContext, 'quotes'>> = {}
+): PrintContext => ({
+  indent: '',
+  maxIndent: 10,
+  indentString: '  ',
+  colorConfig: colorlessConfig,
+  seen: new WeakSet(),
+  quotes: overrides.quotes ?? '"',
+  keys: [],
+  prefix: '',
+})
+
+describe('StringFormatter', () => {
+  it('escapes double quotes when using double quotes', () => {
+    const fmt = new StringFormatter()
+    const ctx = makeCtx()
+    const value = 'a "quote" b'
+    const result = fmt.format(value, ctx)
+    const expected = `${ctx.quotes}${value
+      .split(ctx.quotes)
+      .join(`\\${ctx.quotes}`)}${ctx.quotes}`
+    expect(result).toBe(expected)
+  })
+
+  it('escapes single quotes when using single quotes', () => {
+    const fmt = new StringFormatter()
+    const ctx = makeCtx({ quotes: "'" })
+    const value = "a 'quote' b"
+    const result = fmt.format(value, ctx)
+    const expected = `${ctx.quotes}${value
+      .split(ctx.quotes)
+      .join(`\\${ctx.quotes}`)}${ctx.quotes}`
+    expect(result).toBe(expected)
+  })
+
+  it('does not escape when quotes are disabled', () => {
+    const fmt = new StringFormatter()
+    const ctx = makeCtx({ quotes: '' })
+    const value = 'a "quote" b'
+    const result = fmt.format(value, ctx)
+    expect(result).toBe(value)
+  })
+})