feat: encodeLines for streaming encoding to TOON

2026-01-29 15:24:10 +08:00 · 2025-11-20 18:37:46 +01:00
parent 660ed21e01
commit 2e992aed74
7 changed files with 269 additions and 99 deletions
--- a/docs/cli/index.md
+++ b/docs/cli/index.md
@@ -102,6 +102,16 @@ cat data.json | toon -
 cat data.toon | toon --decode
 ```

+## Performance
+
+### Streaming Encoding
+
+JSON→TOON conversions use line-by-line encoding internally, which avoids holding the entire TOON document in memory. This makes the CLI efficient for large datasets without requiring additional configuration.
+
+::: info Token Statistics
+When using the `--stats` flag, the CLI builds the full TOON string once to compute accurate token counts. For maximum memory efficiency on very large files, omit `--stats`.
+:::
+
 ## Options

 | Option | Description |
--- a/docs/reference/api.md
+++ b/docs/reference/api.md
@@ -127,6 +127,68 @@ encode(data, { delimiter: '\t', keyFolding: 'safe' })
 ```
 :::

+## `encodeLines(value, options?)`
+
+Converts any JSON-serializable value to TOON format as a sequence of lines, without building the full string in memory. Suitable for streaming large outputs to files, HTTP responses, or process stdout.
+
+```ts
+import { encodeLines } from '@toon-format/toon'
+
+// Stream to stdout
+for (const line of encodeLines(data)) {
+  console.log(line)
+}
+
+// Write to file line-by-line
+const lines = encodeLines(data, { indent: 2, delimiter: '\t' })
+for (const line of lines) {
+  await writeToStream(`${line}\n`)
+}
+
+// Collect to array
+const lineArray = Array.from(encodeLines(data))
+```
+
+### Parameters
+
+| Parameter | Type | Description |
+|-----------|------|-------------|
+| `value` | `unknown` | Any JSON-serializable value (object, array, primitive, or nested structure) |
+| `options` | `EncodeOptions?` | Optional encoding options (same as `encode()`) |
+
+### Return Value
+
+Returns an `Iterable<string>` that yields TOON lines one at a time. Each yielded string is a single line without a trailing newline character.
+
+::: info Relationship to `encode()`
+`encode(value, options)` is equivalent to:
+```ts
+Array.from(encodeLines(value, options)).join('\n')
+```
+:::
+
+### Example
+
+```ts
+import { createWriteStream } from 'node:fs'
+import { encodeLines } from '@toon-format/toon'
+
+const data = {
+  items: Array.from({ length: 100000 }, (_, i) => ({
+    id: i,
+    name: `Item ${i}`,
+    value: Math.random()
+  }))
+}
+
+// Stream large dataset to file
+const stream = createWriteStream('output.toon')
+for (const line of encodeLines(data, { delimiter: '\t' })) {
+  stream.write(`${line}\n`)
+}
+stream.end()
+```
+
 ## `decode(input, options?)`

 Converts a TOON-formatted string back to JavaScript values.
--- a/packages/cli/src/conversion.ts
+++ b/packages/cli/src/conversion.ts
@@ -5,7 +5,7 @@ import * as path from 'node:path'
 import process from 'node:process'
 import { consola } from 'consola'
 import { estimateTokenCount } from 'tokenx'
-import { decode, encode } from '../../toon/src'
+import { decode, encode, encodeLines } from '../../toon/src'
 import { formatInputLabel, readInput } from './utils'

 export async function encodeToToon(config: {
@@ -34,7 +34,17 @@ export async function encodeToToon(config: {
    flattenDepth: config.flattenDepth,
  }

-  const toonOutput = encode(data, encodeOptions)
+  let toonOutput: string
+
+  // When printing stats, we need the full string for token counting
+  if (config.printStats) {
+    toonOutput = encode(data, encodeOptions)
+  }
+  else {
+    // Use streaming encoder for non-stats path
+    const lines = Array.from(encodeLines(data, encodeOptions))
+    toonOutput = lines.join('\n')
+  }

  if (config.output) {
    await fsp.writeFile(config.output, toonOutput, 'utf-8')
--- a/packages/toon/src/encode/encoders.ts
+++ b/packages/toon/src/encode/encoders.ts
@@ -1,34 +1,42 @@
 import type { Depth, JsonArray, JsonObject, JsonPrimitive, JsonValue, ResolvedEncodeOptions } from '../types'
-import { DOT, LIST_ITEM_MARKER } from '../constants'
+import { DOT, LIST_ITEM_MARKER, LIST_ITEM_PREFIX } from '../constants'
 import { tryFoldKeyChain } from './folding'
 import { isArrayOfArrays, isArrayOfObjects, isArrayOfPrimitives, isEmptyObject, isJsonArray, isJsonObject, isJsonPrimitive } from './normalize'
 import { encodeAndJoinPrimitives, encodeKey, encodePrimitive, formatHeader } from './primitives'
-import { LineWriter } from './writer'

 // #region Encode normalized JsonValue

-export function encodeValue(value: JsonValue, options: ResolvedEncodeOptions): string {
+export function* encodeJsonValue(value: JsonValue, options: ResolvedEncodeOptions, depth: Depth): Generator<string> {
  if (isJsonPrimitive(value)) {
-    return encodePrimitive(value, options.delimiter)
-  }
+    // Primitives at root level are returned as a single line
+    const encodedPrimitive = encodePrimitive(value, options.delimiter)

-  const writer = new LineWriter(options.indent)
+    if (encodedPrimitive !== '')
+      yield encodedPrimitive
+
+    return
+  }

  if (isJsonArray(value)) {
-    encodeArray(undefined, value, writer, 0, options)
+    yield* encodeArrayLines(undefined, value, depth, options)
  }
  else if (isJsonObject(value)) {
-    encodeObject(value, writer, 0, options)
+    yield* encodeObjectLines(value, depth, options)
  }
-
-  return writer.toString()
 }

 // #endregion

 // #region Object encoding

-export function encodeObject(value: JsonObject, writer: LineWriter, depth: Depth, options: ResolvedEncodeOptions, rootLiteralKeys?: Set<string>, pathPrefix?: string, remainingDepth?: number): void {
+export function* encodeObjectLines(
+  value: JsonObject,
+  depth: Depth,
+  options: ResolvedEncodeOptions,
+  rootLiteralKeys?: Set<string>,
+  pathPrefix?: string,
+  remainingDepth?: number,
+): Generator<string> {
  const keys = Object.keys(value)

  // At root level (depth 0), collect all literal dotted keys for collision checking
@@ -39,11 +47,20 @@ export function encodeObject(value: JsonObject, writer: LineWriter, depth: Depth
  const effectiveFlattenDepth = remainingDepth ?? options.flattenDepth

  for (const [key, val] of Object.entries(value)) {
-    encodeKeyValuePair(key, val, writer, depth, options, keys, rootLiteralKeys, pathPrefix, effectiveFlattenDepth)
+    yield* encodeKeyValuePairLines(key, val, depth, options, keys, rootLiteralKeys, pathPrefix, effectiveFlattenDepth)
  }
 }

-export function encodeKeyValuePair(key: string, value: JsonValue, writer: LineWriter, depth: Depth, options: ResolvedEncodeOptions, siblings?: readonly string[], rootLiteralKeys?: Set<string>, pathPrefix?: string, flattenDepth?: number): void {
+export function* encodeKeyValuePairLines(
+  key: string,
+  value: JsonValue,
+  depth: Depth,
+  options: ResolvedEncodeOptions,
+  siblings?: readonly string[],
+  rootLiteralKeys?: Set<string>,
+  pathPrefix?: string,
+  flattenDepth?: number,
+): Generator<string> {
  const currentPath = pathPrefix ? `${pathPrefix}${DOT}${key}` : key
  const effectiveFlattenDepth = flattenDepth ?? options.flattenDepth

@@ -59,26 +76,26 @@ export function encodeKeyValuePair(key: string, value: JsonValue, writer: LineWr
      if (remainder === undefined) {
        // The folded chain ended at a leaf (primitive, array, or empty object)
        if (isJsonPrimitive(leafValue)) {
-          writer.push(depth, `${encodedFoldedKey}: ${encodePrimitive(leafValue, options.delimiter)}`)
+          yield indentedLine(depth, `${encodedFoldedKey}: ${encodePrimitive(leafValue, options.delimiter)}`, options.indent)
          return
        }
        else if (isJsonArray(leafValue)) {
-          encodeArray(foldedKey, leafValue, writer, depth, options)
+          yield* encodeArrayLines(foldedKey, leafValue, depth, options)
          return
        }
        else if (isJsonObject(leafValue) && isEmptyObject(leafValue)) {
-          writer.push(depth, `${encodedFoldedKey}:`)
+          yield indentedLine(depth, `${encodedFoldedKey}:`, options.indent)
          return
        }
      }

      // Case 2: Partially folded with a tail object
      if (isJsonObject(remainder)) {
-        writer.push(depth, `${encodedFoldedKey}:`)
+        yield indentedLine(depth, `${encodedFoldedKey}:`, options.indent)
        // Calculate remaining depth budget (subtract segments already folded)
        const remainingDepth = effectiveFlattenDepth - segmentCount
        const foldedPath = pathPrefix ? `${pathPrefix}${DOT}${foldedKey}` : foldedKey
-        encodeObject(remainder, writer, depth + 1, options, rootLiteralKeys, foldedPath, remainingDepth)
+        yield* encodeObjectLines(remainder, depth + 1, options, rootLiteralKeys, foldedPath, remainingDepth)
        return
      }
    }
@@ -88,15 +105,15 @@ export function encodeKeyValuePair(key: string, value: JsonValue, writer: LineWr
  const encodedKey = encodeKey(key)

  if (isJsonPrimitive(value)) {
-    writer.push(depth, `${encodedKey}: ${encodePrimitive(value, options.delimiter)}`)
+    yield indentedLine(depth, `${encodedKey}: ${encodePrimitive(value, options.delimiter)}`, options.indent)
  }
  else if (isJsonArray(value)) {
-    encodeArray(key, value, writer, depth, options)
+    yield* encodeArrayLines(key, value, depth, options)
  }
  else if (isJsonObject(value)) {
-    writer.push(depth, `${encodedKey}:`)
+    yield indentedLine(depth, `${encodedKey}:`, options.indent)
    if (!isEmptyObject(value)) {
-      encodeObject(value, writer, depth + 1, options, rootLiteralKeys, currentPath, effectiveFlattenDepth)
+      yield* encodeObjectLines(value, depth + 1, options, rootLiteralKeys, currentPath, effectiveFlattenDepth)
    }
  }
 }
@@ -105,23 +122,22 @@ export function encodeKeyValuePair(key: string, value: JsonValue, writer: LineWr

 // #region Array encoding

-export function encodeArray(
+export function* encodeArrayLines(
  key: string | undefined,
  value: JsonArray,
-  writer: LineWriter,
  depth: Depth,
  options: ResolvedEncodeOptions,
-): void {
+): Generator<string> {
  if (value.length === 0) {
    const header = formatHeader(0, { key, delimiter: options.delimiter })
-    writer.push(depth, header)
+    yield indentedLine(depth, header, options.indent)
    return
  }

  // Primitive array
  if (isArrayOfPrimitives(value)) {
    const arrayLine = encodeInlineArrayLine(value, options.delimiter, key)
-    writer.push(depth, arrayLine)
+    yield indentedLine(depth, arrayLine, options.indent)
    return
  }

@@ -129,7 +145,7 @@ export function encodeArray(
  if (isArrayOfArrays(value)) {
    const allPrimitiveArrays = value.every(arr => isArrayOfPrimitives(arr))
    if (allPrimitiveArrays) {
-      encodeArrayOfArraysAsListItems(key, value, writer, depth, options)
+      yield* encodeArrayOfArraysAsListItemsLines(key, value, depth, options)
      return
    }
  }
@@ -138,36 +154,35 @@ export function encodeArray(
  if (isArrayOfObjects(value)) {
    const header = extractTabularHeader(value)
    if (header) {
-      encodeArrayOfObjectsAsTabular(key, value, header, writer, depth, options)
+      yield* encodeArrayOfObjectsAsTabularLines(key, value, header, depth, options)
    }
    else {
-      encodeMixedArrayAsListItems(key, value, writer, depth, options)
+      yield* encodeMixedArrayAsListItemsLines(key, value, depth, options)
    }
    return
  }

  // Mixed array: fallback to expanded format
-  encodeMixedArrayAsListItems(key, value, writer, depth, options)
+  yield* encodeMixedArrayAsListItemsLines(key, value, depth, options)
 }

 // #endregion

 // #region Array of arrays (expanded format)

-export function encodeArrayOfArraysAsListItems(
+export function* encodeArrayOfArraysAsListItemsLines(
  prefix: string | undefined,
  values: readonly JsonArray[],
-  writer: LineWriter,
  depth: Depth,
  options: ResolvedEncodeOptions,
-): void {
+): Generator<string> {
  const header = formatHeader(values.length, { key: prefix, delimiter: options.delimiter })
-  writer.push(depth, header)
+  yield indentedLine(depth, header, options.indent)

  for (const arr of values) {
    if (isArrayOfPrimitives(arr)) {
      const arrayLine = encodeInlineArrayLine(arr, options.delimiter)
-      writer.pushListItem(depth + 1, arrayLine)
+      yield indentedListItem(depth + 1, arrayLine, options.indent)
    }
  }
 }
@@ -186,18 +201,17 @@ export function encodeInlineArrayLine(values: readonly JsonPrimitive[], delimite

 // #region Array of objects (tabular format)

-export function encodeArrayOfObjectsAsTabular(
+export function* encodeArrayOfObjectsAsTabularLines(
  prefix: string | undefined,
  rows: readonly JsonObject[],
  header: readonly string[],
-  writer: LineWriter,
  depth: Depth,
  options: ResolvedEncodeOptions,
-): void {
+): Generator<string> {
  const formattedHeader = formatHeader(rows.length, { key: prefix, fields: header, delimiter: options.delimiter })
-  writer.push(depth, `${formattedHeader}`)
+  yield indentedLine(depth, formattedHeader, options.indent)

-  writeTabularRows(rows, header, writer, depth + 1, options)
+  yield* writeTabularRowsLines(rows, header, depth + 1, options)
 }

 export function extractTabularHeader(rows: readonly JsonObject[]): string[] | undefined {
@@ -240,17 +254,16 @@ export function isTabularArray(
  return true
 }

-function writeTabularRows(
+function* writeTabularRowsLines(
  rows: readonly JsonObject[],
  header: readonly string[],
-  writer: LineWriter,
  depth: Depth,
  options: ResolvedEncodeOptions,
-): void {
+): Generator<string> {
  for (const row of rows) {
    const values = header.map(key => row[key])
    const joinedValue = encodeAndJoinPrimitives(values as JsonPrimitive[], options.delimiter)
-    writer.push(depth, joinedValue)
+    yield indentedLine(depth, joinedValue, options.indent)
  }
 }

@@ -258,24 +271,27 @@ function writeTabularRows(

 // #region Array of objects (expanded format)

-export function encodeMixedArrayAsListItems(
+export function* encodeMixedArrayAsListItemsLines(
  prefix: string | undefined,
  items: readonly JsonValue[],
-  writer: LineWriter,
  depth: Depth,
  options: ResolvedEncodeOptions,
-): void {
+): Generator<string> {
  const header = formatHeader(items.length, { key: prefix, delimiter: options.delimiter })
-  writer.push(depth, header)
+  yield indentedLine(depth, header, options.indent)

  for (const item of items) {
-    encodeListItemValue(item, writer, depth + 1, options)
+    yield* encodeListItemValueLines(item, depth + 1, options)
  }
 }

-export function encodeObjectAsListItem(obj: JsonObject, writer: LineWriter, depth: Depth, options: ResolvedEncodeOptions): void {
+export function* encodeObjectAsListItemLines(
+  obj: JsonObject,
+  depth: Depth,
+  options: ResolvedEncodeOptions,
+): Generator<string> {
  if (isEmptyObject(obj)) {
-    writer.push(depth, LIST_ITEM_MARKER)
+    yield indentedLine(depth, LIST_ITEM_MARKER, options.indent)
    return
  }

@@ -284,13 +300,13 @@ export function encodeObjectAsListItem(obj: JsonObject, writer: LineWriter, dept
  const encodedKey = encodeKey(firstKey)

  if (isJsonPrimitive(firstValue)) {
-    writer.pushListItem(depth, `${encodedKey}: ${encodePrimitive(firstValue, options.delimiter)}`)
+    yield indentedListItem(depth, `${encodedKey}: ${encodePrimitive(firstValue, options.delimiter)}`, options.indent)
  }
  else if (isJsonArray(firstValue)) {
    if (isArrayOfPrimitives(firstValue)) {
      // Inline format for primitive arrays
      const arrayPropertyLine = encodeInlineArrayLine(firstValue, options.delimiter, firstKey)
-      writer.pushListItem(depth, arrayPropertyLine)
+      yield indentedListItem(depth, arrayPropertyLine, options.indent)
    }
    else if (isArrayOfObjects(firstValue)) {
      // Check if array of objects can use tabular format
@@ -298,38 +314,38 @@ export function encodeObjectAsListItem(obj: JsonObject, writer: LineWriter, dept
      if (header) {
        // Tabular format for uniform arrays of objects
        const formattedHeader = formatHeader(firstValue.length, { key: firstKey, fields: header, delimiter: options.delimiter })
-        writer.pushListItem(depth, formattedHeader)
-        writeTabularRows(firstValue, header, writer, depth + 1, options)
+        yield indentedListItem(depth, formattedHeader, options.indent)
+        yield* writeTabularRowsLines(firstValue, header, depth + 1, options)
      }
      else {
        // Fall back to list format for non-uniform arrays of objects
-        writer.pushListItem(depth, `${encodedKey}[${firstValue.length}]:`)
+        yield indentedListItem(depth, `${encodedKey}[${firstValue.length}]:`, options.indent)
        for (const item of firstValue) {
-          encodeObjectAsListItem(item, writer, depth + 1, options)
+          yield* encodeObjectAsListItemLines(item, depth + 1, options)
        }
      }
    }
    else {
      // Complex arrays on separate lines (array of arrays, etc.)
-      writer.pushListItem(depth, `${encodedKey}[${firstValue.length}]:`)
+      yield indentedListItem(depth, `${encodedKey}[${firstValue.length}]:`, options.indent)

      // Encode array contents at depth + 1
      for (const item of firstValue) {
-        encodeListItemValue(item, writer, depth + 1, options)
+        yield* encodeListItemValueLines(item, depth + 1, options)
      }
    }
  }
  else if (isJsonObject(firstValue)) {
-    writer.pushListItem(depth, `${encodedKey}:`)
+    yield indentedListItem(depth, `${encodedKey}:`, options.indent)
    if (!isEmptyObject(firstValue)) {
-      encodeObject(firstValue, writer, depth + 2, options)
+      yield* encodeObjectLines(firstValue, depth + 2, options)
    }
  }

  // Remaining entries on indented lines
  for (let i = 1; i < entries.length; i++) {
    const [key, value] = entries[i]!
-    encodeKeyValuePair(key, value, writer, depth + 1, options)
+    yield* encodeKeyValuePairLines(key, value, depth + 1, options)
  }
 }

@@ -337,22 +353,34 @@ export function encodeObjectAsListItem(obj: JsonObject, writer: LineWriter, dept

 // #region List item encoding helpers

-function encodeListItemValue(
+function* encodeListItemValueLines(
  value: JsonValue,
-  writer: LineWriter,
  depth: Depth,
  options: ResolvedEncodeOptions,
-): void {
+): Generator<string> {
  if (isJsonPrimitive(value)) {
-    writer.pushListItem(depth, encodePrimitive(value, options.delimiter))
+    yield indentedListItem(depth, encodePrimitive(value, options.delimiter), options.indent)
  }
  else if (isJsonArray(value) && isArrayOfPrimitives(value)) {
    const arrayLine = encodeInlineArrayLine(value, options.delimiter)
-    writer.pushListItem(depth, arrayLine)
+    yield indentedListItem(depth, arrayLine, options.indent)
  }
  else if (isJsonObject(value)) {
-    encodeObjectAsListItem(value, writer, depth, options)
+    yield* encodeObjectAsListItemLines(value, depth, options)
  }
 }

 // #endregion
+
+// #region Indentation helpers
+
+function indentedLine(depth: Depth, content: string, indentSize: number): string {
+  const indentation = ' '.repeat(indentSize * depth)
+  return indentation + content
+}
+
+function indentedListItem(depth: Depth, content: string, indentSize: number): string {
+  return indentedLine(depth, LIST_ITEM_PREFIX + content, indentSize)
+}
+
+// #endregion
--- a/packages/toon/src/encode/writer.ts
+++ b/packages/toon/src/encode/writer.ts
@@ -1,24 +0,0 @@
-import type { Depth } from '../types'
-import { LIST_ITEM_PREFIX } from '../constants'
-
-export class LineWriter {
-  private readonly lines: string[] = []
-  private readonly indentationString: string
-
-  constructor(indentSize: number) {
-    this.indentationString = ' '.repeat(indentSize)
-  }
-
-  push(depth: Depth, content: string): void {
-    const indent = this.indentationString.repeat(depth)
-    this.lines.push(indent + content)
-  }
-
-  pushListItem(depth: Depth, content: string): void {
-    this.push(depth, `${LIST_ITEM_PREFIX}${content}`)
-  }
-
-  toString(): string {
-    return this.lines.join('\n')
-  }
-}
--- a/packages/toon/src/index.ts
+++ b/packages/toon/src/index.ts
@@ -3,7 +3,7 @@ import { DEFAULT_DELIMITER } from './constants'
 import { decodeValueFromLines } from './decode/decoders'
 import { expandPathsSafe } from './decode/expand'
 import { LineCursor, toParsedLines } from './decode/scanner'
-import { encodeValue } from './encode/encoders'
+import { encodeJsonValue } from './encode/encoders'
 import { normalizeValue } from './encode/normalize'

 export { DEFAULT_DELIMITER, DELIMITERS } from './constants'
@@ -20,6 +20,36 @@ export type {
  ResolvedEncodeOptions,
 } from './types'

+/**
+ * Encodes a JavaScript value into TOON format as a sequence of lines.
+ *
+ * This function yields TOON lines one at a time without building the full string,
+ * making it suitable for streaming large outputs to files, HTTP responses, or process stdout.
+ *
+ * @param input - Any JavaScript value (objects, arrays, primitives)
+ * @param options - Optional encoding configuration
+ * @returns Iterable of TOON lines (without trailing newlines)
+ *
+ * @example
+ * ```ts
+ * // Stream to stdout
+ * for (const line of encodeLines({ name: 'Alice', age: 30 })) {
+ *   console.log(line)
+ * }
+ *
+ * // Collect to array
+ * const lines = Array.from(encodeLines(data))
+ *
+ * // Equivalent to encode()
+ * const toonString = Array.from(encodeLines(data, options)).join('\n')
+ * ```
+ */
+export function encodeLines(input: unknown, options?: EncodeOptions): Iterable<string> {
+  const normalizedValue = normalizeValue(input)
+  const resolvedOptions = resolveOptions(options)
+  return encodeJsonValue(normalizedValue, resolvedOptions, 0)
+}
+
 /**
 * Encodes a JavaScript value into TOON format string.
 *
@@ -42,9 +72,7 @@ export type {
 * ```
 */
 export function encode(input: unknown, options?: EncodeOptions): string {
-  const normalizedValue = normalizeValue(input)
-  const resolvedOptions = resolveOptions(options)
-  return encodeValue(normalizedValue, resolvedOptions)
+  return Array.from(encodeLines(input, options)).join('\n')
 }

 /**
--- a/packages/toon/test/encodeLines.test.ts
+++ b/packages/toon/test/encodeLines.test.ts
@@ -0,0 +1,56 @@
+import { describe, expect, it } from 'vitest'
+import { encodeLines } from '../src/index'
+
+describe('encodeLines', () => {
+  it('should yield lines without newline characters', () => {
+    const value = { name: 'Alice', age: 30, city: 'Paris' }
+    const lines = Array.from(encodeLines(value))
+
+    for (const line of lines) {
+      expect(line).not.toContain('\n')
+    }
+  })
+
+  it('should yield zero lines for empty object', () => {
+    const lines = Array.from(encodeLines({}))
+
+    expect(lines.length).toBe(0)
+  })
+
+  it('should be iterable with for-of loop', () => {
+    const value = { x: 10, y: 20 }
+    const collectedLines: string[] = []
+
+    for (const line of encodeLines(value)) {
+      collectedLines.push(line)
+    }
+
+    expect(collectedLines.length).toBe(2)
+    expect(collectedLines[0]).toBe('x: 10')
+    expect(collectedLines[1]).toBe('y: 20')
+  })
+
+  it('should not have trailing spaces in lines', () => {
+    const value = {
+      user: {
+        name: 'Alice',
+        tags: ['a', 'b'],
+        nested: {
+          deep: 'value',
+        },
+      },
+    }
+    const lines = Array.from(encodeLines(value))
+
+    for (const line of lines) {
+      expect(line).not.toMatch(/\s$/)
+    }
+  })
+
+  it('should yield correct number of lines', () => {
+    const value = { a: 1, b: 2, c: 3 }
+    const lines = Array.from(encodeLines(value))
+
+    expect(lines.length).toBe(3)
+  })
+})