refactor(hashline-edit): replace custom diff with diff library

🤖 Generated with assistance of [OhMyOpenCode](https://github.com/code-yeongyu/oh-my-opencode)
2026-02-24 22:30:06 +09:00
parent ddf426c4b3
commit fcb90d92a4
4 changed files with 77 additions and 53 deletions
@@ -0,0 +1,71 @@
+/// <reference types="bun-types" />
+import { describe, expect, it } from "bun:test"
+import { generateUnifiedDiff } from "./diff-utils"
+
+function createNumberedLines(totalLineCount: number): string {
+  return Array.from({ length: totalLineCount }, (_, index) => `line ${index + 1}`).join("\n")
+}
+
+describe("generateUnifiedDiff", () => {
+  it("creates separate hunks for distant changes", () => {
+    //#given
+    const oldContent = createNumberedLines(60)
+    const newLines = oldContent.split("\n")
+    newLines[4] = "line 5 updated"
+    newLines[49] = "line 50 updated"
+    const newContent = newLines.join("\n")
+
+    //#when
+    const diff = generateUnifiedDiff(oldContent, newContent, "sample.txt")
+
+    //#then
+    const hunkHeaders = diff.match(/^@@/gm) ?? []
+    expect(hunkHeaders.length).toBe(2)
+  })
+
+  it("creates a single hunk for adjacent changes", () => {
+    //#given
+    const oldContent = createNumberedLines(20)
+    const newLines = oldContent.split("\n")
+    newLines[9] = "line 10 updated"
+    newLines[10] = "line 11 updated"
+    const newContent = newLines.join("\n")
+
+    //#when
+    const diff = generateUnifiedDiff(oldContent, newContent, "sample.txt")
+
+    //#then
+    const hunkHeaders = diff.match(/^@@/gm) ?? []
+    expect(hunkHeaders.length).toBe(1)
+    expect(diff).toContain(" line 8")
+    expect(diff).toContain(" line 13")
+  })
+
+  it("returns a diff string for identical content", () => {
+    //#given
+    const oldContent = "alpha\nbeta\ngamma"
+    const newContent = "alpha\nbeta\ngamma"
+
+    //#when
+    const diff = generateUnifiedDiff(oldContent, newContent, "sample.txt")
+
+    //#then
+    expect(typeof diff).toBe("string")
+    expect(diff).toContain("--- sample.txt")
+    expect(diff).toContain("+++ sample.txt")
+  })
+
+  it("returns a valid diff when old content is empty", () => {
+    //#given
+    const oldContent = ""
+    const newContent = "first line\nsecond line"
+
+    //#when
+    const diff = generateUnifiedDiff(oldContent, newContent, "sample.txt")
+
+    //#then
+    expect(diff).toContain("--- sample.txt")
+    expect(diff).toContain("+++ sample.txt")
+    expect(diff).toContain("+first line")
+  })
+})