test: add comprehensive unit tests for lib/git.ts

- 20 tests covering run(), convenience functions, fallback behavior
- Tests error handling: timeouts, ENOENT, stderr, exit codes
- Tests getDiffFiles/getDiffStat fallback chains
- Uses vitest mocks for child_process

Author: TerminalGravity

tests/lib/git.test.ts

@@ -0,0 +1,160 @@
+import { describe, it, expect, vi, beforeEach } from "vitest";
+import * as cp from "child_process";
+
+// Mock child_process before importing git module
+vi.mock("child_process", () => ({
+  execFileSync: vi.fn(),
+}));
+
+// Mock files to provide PROJECT_DIR
+vi.mock("../../src/lib/files.js", () => ({
+  PROJECT_DIR: "/tmp/test-project",
+}));
+
+import { run, getBranch, getStatus, getRecentCommits, getLastCommit, getLastCommitTime, getDiffFiles, getStagedFiles, getDiffStat } from "../../src/lib/git.js";
+
+const mockExec = vi.mocked(cp.execFileSync);
+
+beforeEach(() => {
+  mockExec.mockReset();
+});
+
+describe("run()", () => {
+  it("accepts array args and returns trimmed stdout", () => {
+    mockExec.mockReturnValue("  hello world  ");
+    const result = run(["status", "--short"]);
+    expect(result).toBe("hello world");
+    expect(mockExec).toHaveBeenCalledWith("git", ["status", "--short"], expect.objectContaining({
+      cwd: "/tmp/test-project",
+      encoding: "utf-8",
+    }));
+  });
+
+  it("accepts string arg and splits on whitespace", () => {
+    mockExec.mockReturnValue("ok");
+    run("log --oneline -5");
+    expect(mockExec).toHaveBeenCalledWith("git", ["log", "--oneline", "-5"], expect.anything());
+  });
+
+  it("returns timeout message when process is killed", () => {
+    const err: any = new Error("killed");
+    err.killed = true;
+    mockExec.mockImplementation(() => { throw err; });
+    expect(run(["status"])).toBe("[timed out after 10000ms]");
+  });
+
+  it("returns custom timeout value in message", () => {
+    const err: any = new Error("killed");
+    err.signal = "SIGTERM";
+    mockExec.mockImplementation(() => { throw err; });
+    expect(run(["status"], { timeout: 5000 })).toBe("[timed out after 5000ms]");
+  });
+
+  it("returns stderr on failure", () => {
+    const err: any = new Error("fail");
+    err.stdout = "";
+    err.stderr = "fatal: not a git repository";
+    mockExec.mockImplementation(() => { throw err; });
+    expect(run(["status"])).toBe("fatal: not a git repository");
+  });
+
+  it("returns ENOENT message when git not found", () => {
+    const err: any = new Error("fail");
+    err.code = "ENOENT";
+    mockExec.mockImplementation(() => { throw err; });
+    expect(run(["status"])).toBe("[git not found]");
+  });
+
+  it("returns generic failure message when no output", () => {
+    const err: any = new Error("fail");
+    err.status = 128;
+    err.stdout = "";
+    err.stderr = "";
+    mockExec.mockImplementation(() => { throw err; });
+    expect(run(["push"])).toBe("[command failed: git push (exit 128)]");
+  });
+});
+
+describe("convenience functions", () => {
+  it("getBranch calls branch --show-current", () => {
+    mockExec.mockReturnValue("main");
+    expect(getBranch()).toBe("main");
+    expect(mockExec).toHaveBeenCalledWith("git", ["branch", "--show-current"], expect.anything());
+  });
+
+  it("getStatus calls status --short", () => {
+    mockExec.mockReturnValue("M file.ts");
+    expect(getStatus()).toBe("M file.ts");
+  });
+
+  it("getRecentCommits defaults to 5", () => {
+    mockExec.mockReturnValue("abc123 commit");
+    getRecentCommits();
+    expect(mockExec).toHaveBeenCalledWith("git", ["log", "--oneline", "-5"], expect.anything());
+  });
+
+  it("getRecentCommits accepts custom count", () => {
+    mockExec.mockReturnValue("abc123 commit");
+    getRecentCommits(10);
+    expect(mockExec).toHaveBeenCalledWith("git", ["log", "--oneline", "-10"], expect.anything());
+  });
+
+  it("getLastCommit returns single oneline", () => {
+    mockExec.mockReturnValue("abc123 fix bug");
+    expect(getLastCommit()).toBe("abc123 fix bug");
+  });
+
+  it("getLastCommitTime returns timestamp", () => {
+    mockExec.mockReturnValue("2026-03-09 10:00:00 -0700");
+    expect(getLastCommitTime()).toBe("2026-03-09 10:00:00 -0700");
+  });
+});
+
+describe("getDiffFiles()", () => {
+  it("returns diff output on success", () => {
+    mockExec.mockReturnValue("src/index.ts\nsrc/lib/git.ts");
+    expect(getDiffFiles()).toBe("src/index.ts\nsrc/lib/git.ts");
+  });
+
+  it("falls back to HEAD~1 when primary ref fails", () => {
+    mockExec
+      .mockReturnValueOnce("[command failed: git diff (exit 128)]")
+      .mockReturnValueOnce("src/index.ts");
+    expect(getDiffFiles("origin/main")).toBe("src/index.ts");
+  });
+
+  it("returns 'no commits' when both refs fail", () => {
+    mockExec
+      .mockReturnValueOnce("[command failed]")
+      .mockReturnValueOnce("[command failed]");
+    expect(getDiffFiles()).toBe("no commits");
+  });
+});
+
+describe("getDiffStat()", () => {
+  it("returns stat on success", () => {
+    mockExec.mockReturnValue("2 files changed, 10 insertions(+)");
+    expect(getDiffStat()).toBe("2 files changed, 10 insertions(+)");
+  });
+
+  it("falls back to HEAD~3 when primary fails", () => {
+    mockExec
+      .mockReturnValueOnce("[command failed]")
+      .mockReturnValueOnce("1 file changed");
+    expect(getDiffStat("origin/main")).toBe("1 file changed");
+  });
+
+  it("returns fallback message when both fail", () => {
+    mockExec
+      .mockReturnValueOnce("[command failed]")
+      .mockReturnValueOnce("[command failed]");
+    expect(getDiffStat()).toBe("no diff stats available");
+  });
+});
+
+describe("getStagedFiles()", () => {
+  it("returns staged file list", () => {
+    mockExec.mockReturnValue("src/new.ts");
+    expect(getStagedFiles()).toBe("src/new.ts");
+  });
+});