opencode/packages/core/test/patch.test.ts

import { describe, expect, test } from "bun:test"
import { Patch } from "@opencode-ai/util/patch"
import { Result } from "effect"

const parse = (input: string) => Result.getOrThrow(Patch.parse(input))

describe("Patch", () => {
  test("parses add, update, and delete hunks", () => {
    expect(
      parse(
        "*** Begin Patch\n*** Add File: add.txt\n+added\n*** Update File: update.txt\n@@ section\n-old\n+new\n*** Delete File: delete.txt\n*** End Patch",
      ),
    ).toEqual([
      { type: "add", path: "add.txt", contents: "added" },
      {
        type: "update",
        path: "update.txt",
        chunks: [{ oldLines: ["old"], newLines: ["new"], changeContext: "section", endOfFile: undefined }],
        movePath: undefined,
      },
      { type: "delete", path: "delete.txt" },
    ])
  })

  test("parses a file move", () => {
    expect(
      parse("*** Begin Patch\n*** Update File: old.txt\n*** Move to: new.txt\n@@\n-old\n+new\n*** End Patch"),
    ).toEqual([
      {
        type: "update",
        path: "old.txt",
        movePath: "new.txt",
        chunks: [{ oldLines: ["old"], newLines: ["new"], changeContext: undefined, endOfFile: undefined }],
      },
    ])
  })

  test("identifies the missing patch boundary", () => {
    expect(() => parse("This is not a valid patch")).toThrow("The first line of the patch must be '*** Begin Patch'")
    expect(() => parse("*** Begin Patch\n*** Add File: add.txt\n+added")).toThrow(
      "The last line of the patch must be '*** End Patch'",
    )
  })

  test("strips a heredoc wrapper", () => {
    expect(parse("cat <<'EOF'\n*** Begin Patch\n*** Add File: add.txt\n+added\n*** End Patch\nEOF")).toEqual([
      { type: "add", path: "add.txt", contents: "added" },
    ])
  })

  test("strips a heredoc wrapper without cat", () => {
    expect(parse("<<EOF\n*** Begin Patch\n*** Add File: add.txt\n+added\n*** End Patch\nEOF")).toEqual([
      { type: "add", path: "add.txt", contents: "added" },
    ])
  })

  test("parses a whitespace-padded hunk header", () => {
    expect(parse("*** Begin Patch\n  *** Update File: foo.txt\n@@\n-old\n+new\n*** End Patch")).toEqual([
      {
        type: "update",
        path: "foo.txt",
        movePath: undefined,
        chunks: [{ oldLines: ["old"], newLines: ["new"], changeContext: undefined, endOfFile: undefined }],
      },
    ])
  })

  test("parses leading and trailing whitespace around patch markers", () => {
    expect(parse(" *** Begin Patch\n*** Update File: file.txt\n@@\n-one\n+two\n*** End Patch ")).toEqual([
      {
        type: "update",
        path: "file.txt",
        movePath: undefined,
        chunks: [{ oldLines: ["one"], newLines: ["two"], changeContext: undefined, endOfFile: undefined }],
      },
    ])
  })

  test("parses whitespace on the inner sides of patch marker lines", () => {
    expect(parse("*** Begin Patch \n*** Update File: file.txt\n@@\n-one\n+two\n *** End Patch")).toEqual([
      {
        type: "update",
        path: "file.txt",
        movePath: undefined,
        chunks: [{ oldLines: ["one"], newLines: ["two"], changeContext: undefined, endOfFile: undefined }],
      },
    ])
  })

  test("strips one carriage return from CRLF patch lines", () => {
    expect(parse("*** Begin Patch\r\n*** Update File: file.txt\r\n@@\r\n-old\r\n+new\r\n*** End Patch\r\n")).toEqual([
      {
        type: "update",
        path: "file.txt",
        movePath: undefined,
        chunks: [{ oldLines: ["old"], newLines: ["new"], changeContext: undefined, endOfFile: undefined }],
      },
    ])
  })

  test("preserves an extra carriage return in CRLF patch lines", () => {
    expect(parse("*** Begin Patch\r\n*** Update File: file.txt\r\n@@\r\n-old\r\r\n+new\r\n*** End Patch\r\n")).toEqual([
      {
        type: "update",
        path: "file.txt",
        movePath: undefined,
        chunks: [{ oldLines: ["old\r"], newLines: ["new"], changeContext: undefined, endOfFile: undefined }],
      },
    ])
  })

  test("preserves the end-of-file marker", () => {
    expect(
      parse(
        "*** Begin Patch\n*** Update File: file.txt\n@@\n+quux\n*** End of File\n\n*** End Patch",
      ),
    ).toEqual([
      {
        type: "update",
        path: "file.txt",
        movePath: undefined,
        chunks: [{ oldLines: [], newLines: ["quux"], changeContext: undefined, endOfFile: true }],
      },
    ])
  })

  test("derives fuzzy line updates while preserving BOM", () => {
    const update = Patch.derive("update.txt", [{ oldLines: ["  old   "], newLines: ["new"] }], "\uFEFFold\n")
    expect(update).toEqual({ content: "new\n", bom: true })
    expect(Patch.joinBom(update.content, update.bom)).toBe("\uFEFFnew\n")
  })

  test("derives multiple update chunks", () => {
    expect(
      Patch.derive(
        "update.txt",
        [
          { oldLines: ["line 2"], newLines: ["LINE 2"] },
          { oldLines: ["line 4"], newLines: ["LINE 4"] },
        ],
        "line 1\nline 2\nline 3\nline 4\n",
      ).content,
    ).toBe("line 1\nLINE 2\nline 3\nLINE 4\n")
  })

  test("updates empty files and adds a trailing newline", () => {
    expect(Patch.derive("empty.txt", [{ oldLines: [], newLines: ["First line"] }], "").content).toBe("First line\n")
    expect(Patch.derive("no-newline.txt", [{ oldLines: ["old"], newLines: ["new"] }], "old").content).toBe("new\n")
  })

  test("disambiguates updates with change context", () => {
    expect(
      Patch.derive(
        "update.txt",
        [{ oldLines: ["x=10"], newLines: ["x=11"], changeContext: "fn b" }],
        "fn a\nx=10\nfn b\nx=10\n",
      ).content,
    ).toBe("fn a\nx=10\nfn b\nx=11\n")
  })

  test("matches leading, trailing, and Unicode punctuation differences", () => {
    expect(Patch.derive("leading.txt", [{ oldLines: ["line"], newLines: ["next"] }], "  line\n").content).toBe("next\n")
    expect(Patch.derive("trailing.txt", [{ oldLines: ["line"], newLines: ["next"] }], "line  \n").content).toBe(
      "next\n",
    )
    expect(
      Patch.derive("unicode.txt", [{ oldLines: ['He said "hello"'], newLines: ['He said "hi"'] }], "He said “hello”\n")
        .content,
    ).toBe('He said "hi"\n')
  })

  test("matches EOF-anchored chunks from the end", () => {
    expect(
      Patch.derive(
        "update.txt",
        [{ oldLines: ["marker", "end"], newLines: ["marker changed", "end"], endOfFile: true }],
        "marker\nmiddle\nmarker\nend\n",
      ).content,
    ).toBe("marker\nmiddle\nmarker changed\nend\n")
  })

  test("does not fall back to a non-EOF match", () => {
    expect(() =>
      Patch.derive(
        "update.txt",
        [{ oldLines: ["marker", "end"], newLines: ["changed", "end"], endOfFile: true }],
        "marker\nend\nmiddle\n",
      ),
    ).toThrow("Failed to find expected lines")
  })

  test("matches V1 lenient parsing of malformed hunk bodies", () => {
    expect(parse("*** Begin Patch\n*** Add File: add.txt\nmissing plus\n*** End Patch")).toEqual([
      { type: "add", path: "add.txt", contents: "" },
    ])
    expect(parse("*** Begin Patch\n*** Update File: update.txt\n*** End Patch")).toEqual([
      { type: "update", path: "update.txt", movePath: undefined, chunks: [] },
    ])
    expect(parse("*** Begin Patch\n*** Delete File: delete.txt\nunexpected body\n*** End Patch")).toEqual([
      { type: "delete", path: "delete.txt" },
    ])
  })
})