basic BMAD setup

.agents/skills/bmad-retrospective/scripts/tests/test_git_evidence.py

@@ -0,0 +1,605 @@
+# /// script
+# requires-python = ">=3.11"
+# dependencies = ["pytest>=8.0"]
+# ///
+"""Tests for git_evidence.py — measurement over a real temp git repo.
+
+Run: uv run scripts/tests/test_git_evidence.py
+ or: uv run --with pytest -m pytest scripts/tests/test_git_evidence.py
+"""
+
+import json
+import os
+import subprocess
+import sys
+import unicodedata
+from pathlib import Path
+
+import pytest
+
+SCRIPT = Path(__file__).resolve().parents[1] / "git_evidence.py"
+
+# The fixture commit identity, shared by both git helpers below.
+_IDENT = {
+    "GIT_AUTHOR_NAME": "T",
+    "GIT_AUTHOR_EMAIL": "t@t",
+    "GIT_COMMITTER_NAME": "T",
+    "GIT_COMMITTER_EMAIL": "t@t",
+}
+
+
+def _git_env(repo):
+    """The environment every fixture git runs under, layered outward.
+
+    Inherit the real environment (PATH above all: git lives in /opt/homebrew,
+    /usr/local, or a nix store as readily as /usr/bin, and an env holding only
+    GIT_* vars sends execvp to os.defpath), then strip every ambient GIT_* var
+    -- GIT_DIR, GIT_WORK_TREE and GIT_CONFIG_COUNT would each silently redirect
+    or reconfigure the fixture -- and pin identity plus every source git reads
+    for settings, so nothing on the developer's machine can reach the fixture:
+
+    - gitconfig (commit.gpgsign, core.autocrlf, core.hooksPath,
+      init.defaultBranch). GIT_CONFIG_NOSYSTEM/GIT_CONFIG_GLOBAL cover
+      git >= 2.32; HOME and XDG_CONFIG_HOME cover older git, and are set to the
+      repo's parent directory -- always a per-test directory under pytest's
+      tmp_path -- so nothing is ever planted inside the working tree.
+    - gitattributes, a separate source GIT_CONFIG_NOSYSTEM does not cover: a
+      system `* -diff` rule would make numstat call every path binary and take
+      the churn assertions down with it. GIT_ATTR_NOSYSTEM shuts it out.
+    - the locale. LC_ALL/LANG are pinned to C, matching _run/_proc's existing
+      pin, so fixture git's text output cannot vary with the developer's
+      locale. Inheriting the environment is what makes this pin necessary:
+      the old four-variable env had no locale in it to inherit.
+    """
+    env = {k: v for k, v in os.environ.items() if not k.startswith("GIT_")}
+    env.update(_IDENT)
+    env["GIT_CONFIG_NOSYSTEM"] = "1"
+    env["GIT_ATTR_NOSYSTEM"] = "1"
+    env["GIT_CONFIG_GLOBAL"] = os.devnull
+    env["HOME"] = env["XDG_CONFIG_HOME"] = str(Path(repo).parent)
+    env["LC_ALL"] = env["LANG"] = "C"
+    return env
+
+
+def _json(proc):
+    """Parse the JSON-only stdout contract, surfacing a crash instead of hiding
+    it behind a JSONDecodeError."""
+    assert proc.stdout, f"empty stdout; stderr was: {proc.stderr}"
+    assert "Traceback" not in proc.stderr, proc.stderr
+    return json.loads(proc.stdout)
+
+
+def _run(*args):
+    # LC_ALL=C keeps git's error strings in English so assertions on them
+    # are stable across locales.
+    proc = subprocess.run(
+        ["uv", "run", str(SCRIPT), *args],
+        capture_output=True,
+        text=True,
+        env={**os.environ, "LC_ALL": "C", "LANG": "C"},
+    )
+    return proc.returncode, _json(proc)
+
+
+def _proc(*args, env=None):
+    """Run the script and return the raw process, so a test can assert on the
+    exit code and stderr together — and so `env` can carry an overlay (a
+    locale, an ambient GIT_DIR) that `_run` has no way to pass."""
+    overlay = {"LC_ALL": "C", "LANG": "C"}
+    if env:
+        overlay.update(env)
+    return subprocess.run(
+        ["uv", "run", str(SCRIPT), *args],
+        capture_output=True,
+        text=True,
+        env={**os.environ, **overlay},
+    )
+
+
+def _git(repo, *args):
+    subprocess.run(
+        ["git", "-C", str(repo), *args],
+        check=True,
+        capture_output=True,
+        env=_git_env(repo),
+    )
+
+
+def _git_unchecked(repo, *args):
+    """`git` that tolerates a non-zero exit — the conflicting merge in
+    `_merge_repo` is supposed to fail, and the hand resolution comes after it.
+    Same environment as `_git`, which runs with check=True."""
+    return subprocess.run(
+        ["git", "-C", str(repo), *args],
+        capture_output=True,
+        text=True,
+        env=_git_env(repo),
+    )
+
+
+def _make_repo(tmp_path):
+    repo = tmp_path / "repo"
+    repo.mkdir()
+    _git(repo, "init", "-q")
+    (repo / "a.py").write_text("one\ntwo\n")
+    _git(repo, "add", "-A")
+    _git(repo, "commit", "-qm", "epic-1-1 initial a")
+    (repo / "a.py").write_text("one\ntwo\nthree\nfour\n")
+    (repo / "b.py").write_text("x\n")
+    _git(repo, "add", "-A")
+    _git(repo, "commit", "-qm", "epic-1-2 grow a, add b")
+    return repo
+
+
+def test_no_range_returns_empty(tmp_path):
+    repo = _make_repo(tmp_path)
+    code, out = _run("--repo", str(repo))
+    assert code == 0
+    assert out["range"] is None
+    assert out["commits"] == [] and out["files"] == []
+
+
+def test_measures_commits_and_files_with_attribution(tmp_path):
+    repo = _make_repo(tmp_path)
+    code, out = _run("--repo", str(repo), "--range", "HEAD~1..HEAD", "--stories", "1-2,1-1")
+    assert code == 0
+    assert out["range"] == "HEAD~1..HEAD"
+    assert out["commit_count"] == 1
+    # The single commit in range is the second one; attributed to story "1-2".
+    assert out["commits"][0]["stories"] == ["1-2"]
+    files = {f["path"]: f for f in out["files"]}
+    # a.py grew by two lines, b.py added one — measured, not judged.
+    assert files["a.py"]["added"] == 2 and files["a.py"]["net"] == 2
+    assert files["b.py"]["added"] == 1
+
+
+def test_story_attribution_respects_word_boundary(tmp_path):
+    # Story id "1-2" must NOT match a commit subject mentioning "11-2".
+    repo = tmp_path / "repo"
+    repo.mkdir()
+    _git(repo, "init", "-q")
+    (repo / "f.py").write_text("a\n")
+    _git(repo, "add", "-A")
+    _git(repo, "commit", "-qm", "base")
+    (repo / "f.py").write_text("a\nb\n")
+    _git(repo, "add", "-A")
+    _git(repo, "commit", "-qm", "epic-11-2 unrelated story")
+    code, out = _run("--repo", str(repo), "--range", "HEAD~1..HEAD", "--stories", "1-2")
+    assert code == 0
+    assert out["commits"][0]["stories"] == []
+
+
+def test_bad_range_errors_as_json(tmp_path):
+    repo = _make_repo(tmp_path)
+    code, out = _run("--repo", str(repo), "--range", "nope..alsonope")
+    assert code == 1
+    assert out["ok"] is False and out["error"]
+
+
+def test_single_rev_range_rejected(tmp_path):
+    # A single rev is not a range: git would log ALL history up to it and the
+    # script would report the whole repo as the epic's evidence.
+    repo = _make_repo(tmp_path)
+    code, out = _run("--repo", str(repo), "--range", "HEAD")
+    assert code == 2
+    assert out["ok"] is False and "invalid --range" in out["error"]
+
+
+def test_pathspec_range_rejected(tmp_path):
+    # A path that exists must not be silently consumed as a pathspec.
+    repo = _make_repo(tmp_path)
+    code, out = _run("--repo", str(repo), "--range", "a.py")
+    assert code == 2
+    assert out["ok"] is False and "invalid --range" in out["error"]
+
+
+def test_range_shaped_pathspec_forced_to_rev_parse(tmp_path):
+    # A committed file literally named "a..b" passes the REV..REV shape check;
+    # without the trailing "--" in the git argv, git silently logs that FILE's
+    # history with exit 0. The "--" forces rev interpretation, so this must
+    # error instead of measuring the decoy.
+    repo = _make_repo(tmp_path)
+    (repo / "a..b").write_text("decoy\n")
+    _git(repo, "add", "-A")
+    _git(repo, "commit", "-qm", "add decoy file named like a range")
+    code, out = _run("--repo", str(repo), "--range", "a..b")
+    assert code == 1
+    assert out["ok"] is False and "bad revision" in out["error"]
+
+
+def test_option_like_range_rejected(tmp_path):
+    # A range starting with "-" must never reach git, where it would be
+    # consumed as an option (e.g. --output=... writes an arbitrary file).
+    repo = _make_repo(tmp_path)
+    code, out = _run("--repo", str(repo), "--range=--output=evil.txt")
+    assert code == 2
+    assert out["ok"] is False and "invalid --range" in out["error"]
+    assert not (repo / "evil.txt").exists()
+
+
+def test_degenerate_range_shapes_rejected(tmp_path):
+    # Shapes that contain ".." but are not REV..REV: git would silently
+    # default an empty endpoint to HEAD ("..", "a..", "..HEAD"), a leading
+    # dash must never reach git even when dots are present ("-3..HEAD"),
+    # unstripped values must not slip past the dash guard, and a three-dot
+    # range is a symmetric difference — git would measure commits reachable
+    # from either endpoint but not both, a different evidence set entirely.
+    repo = _make_repo(tmp_path)
+    for bad in (
+        "..",
+        "a..",
+        "..HEAD",
+        "-3..HEAD",
+        " HEAD~1..HEAD",
+        "HEAD~1...HEAD",
+        "a...b",
+    ):
+        code, out = _run("--repo", str(repo), f"--range={bad}")
+        assert code == 2, f"accepted {bad!r}"
+        assert out["ok"] is False and "invalid --range" in out["error"], bad
+
+
+def test_malformed_args_emit_json_not_usage(tmp_path):
+    # An unknown flag must still land on the JSON contract, not argparse's
+    # plain usage text on stderr.
+    code, out = _run("--bogus-flag")
+    assert code != 0
+    assert out["ok"] is False and out["error"]
+
+
+def test_help_flags_emit_json_not_usage():
+    # argparse's built-in help action bypasses the error() override entirely --
+    # it prints usage text on stdout and exits 0, which breaks the JSON-only
+    # contract for a machine consumer. add_help=False demotes -h to an ordinary
+    # unrecognized argument, which error() already handles.
+    for flag in ("-h", "--help"):
+        proc = _proc(flag)
+        # Exit 2 specifically: the module docstring reserves 2 for argument
+        # errors and 1 for git/I-O failures, so collapsing them must fail here.
+        assert proc.returncode == 2, flag
+        assert "usage:" not in proc.stdout, flag
+        out = _json(proc)
+        assert out["ok"] is False and out["error"], flag
+
+
+# --- helpers for the fixtures below -----------------------------------------
+
+
+def _rev(repo, ref):
+    return _git_unchecked(repo, "rev-parse", ref).stdout.strip()
+
+
+def _merge_repo(tmp_path):
+    """Two story branches merged into the mainline; the second merge conflicts
+    and is resolved by hand, adding a line neither branch had. Returns
+    (repo, base_sha) — `base_sha..HEAD` is the epic range."""
+    repo = tmp_path / "repo"
+    repo.mkdir()
+    _git(repo, "init", "-q", "-b", "main")
+    (repo / "s.py").write_text("l1\nl2\nl3\n")
+    _git(repo, "add", "-A")
+    _git(repo, "commit", "-qm", "base")
+    base = _rev(repo, "HEAD")
+
+    _git(repo, "checkout", "-q", "-b", "s1")
+    (repo / "s.py").write_text("l1\nA\nl3\n")
+    _git(repo, "commit", "-qam", "epic-1-2 story one")
+    _git(repo, "checkout", "-q", "main")
+    _git(repo, "merge", "-q", "--no-ff", "s1", "-m", "merge story 1-2")
+
+    _git(repo, "checkout", "-q", "-b", "s2", base)
+    (repo / "s.py").write_text("l1\nB\nl3\n")
+    _git(repo, "commit", "-qam", "epic-1-3 story two")
+    _git(repo, "checkout", "-q", "main")
+    conflicted = _git_unchecked(repo, "merge", "--no-ff", "s2", "-m", "merge story 1-3")
+    assert conflicted.returncode != 0, "fixture expected a merge conflict"
+    (repo / "s.py").write_text("l1\nAB\nl3\nl4\n")  # hand resolution
+    _git(repo, "add", "-A")
+    _git(repo, "commit", "-qm", "merge story 1-3")
+    return repo, base
+
+
+def test_rename_yields_two_openable_paths(tmp_path):
+    # git's default rename detection emits "src/{mod.py => renamed.py}" — an
+    # unopenable pseudo-path that also splits one file's churn across keys.
+    # --no-renames makes the rename an honest delete + add.
+    repo = tmp_path / "repo"
+    repo.mkdir()
+    _git(repo, "init", "-q", "-b", "main")
+    (repo / "src").mkdir()
+    (repo / "src" / "mod.py").write_text("l1\nl2\nl3\nl4\nl5\nl6\n")
+    _git(repo, "add", "-A")
+    _git(repo, "commit", "-qm", "base")
+    base = _rev(repo, "HEAD")
+    _git(repo, "mv", "src/mod.py", "src/renamed.py")
+    _git(repo, "commit", "-qm", "rename mod")
+    (repo / "src" / "renamed.py").write_text("l1\nl2\nl3\nl4\nl5\nl6\nl7\n")
+    _git(repo, "commit", "-qam", "add a line after the rename")
+
+    out = _json(_proc("--repo", str(repo), "--range", f"{base}..HEAD"))
+    files = {f["path"]: f for f in out["files"]}
+    assert not any("=>" in path for path in files), sorted(files)
+    assert files["src/mod.py"]["added"] == 0
+    assert files["src/mod.py"]["deleted"] == 6
+    assert files["src/renamed.py"]["added"] == 7
+    assert files["src/renamed.py"]["deleted"] == 0
+
+
+def _accented_repo(tmp_path):
+    repo = tmp_path / "repo"
+    repo.mkdir()
+    _git(repo, "init", "-q", "-b", "main")
+    (repo / "src").mkdir()
+    (repo / "src" / "café.py").write_text("ca\n")
+    _git(repo, "add", "-A")
+    _git(repo, "commit", "-qm", "base")
+    base = _rev(repo, "HEAD")
+    (repo / "src" / "café.py").write_text("ca\ncb\n")
+    _git(repo, "commit", "-qam", "touch the accented file")
+    return repo, base
+
+
+def _assert_accented_path(repo, out):
+    paths = [f["path"] for f in out["files"]]
+    assert len(paths) == 1
+    assert "\\" not in paths[0] and '"' not in paths[0], paths
+    assert unicodedata.normalize("NFC", paths[0]) == "src/café.py"
+    # The reported path is a real path: it opens under --repo.
+    assert (repo / paths[0]).read_text() == "ca\ncb\n"
+
+
+def test_non_ascii_path_is_a_real_string(tmp_path):
+    # Without core.quotePath=false git emits "src/caf\303\251.py" — quoted and
+    # octal-escaped, so the documented "open the ranked files" step cannot.
+    repo, base = _accented_repo(tmp_path)
+    _assert_accented_path(repo, _json(_proc("--repo", str(repo), "--range", f"{base}..HEAD")))
+
+
+def test_non_ascii_path_survives_a_non_utf8_locale(tmp_path):
+    # Pins the explicit encoding="utf-8" on the subprocess. Modern CPython's
+    # UTF-8 mode hides its absence even under LC_ALL=C, so the pin only bites
+    # with UTF-8 mode and C-locale coercion both off — where the interpreter
+    # default is US-ASCII and git's UTF-8 path bytes fail to decode, taking the
+    # whole measurement down with them.
+    repo, base = _accented_repo(tmp_path)
+    out = _json(
+        _proc(
+            "--repo",
+            str(repo),
+            "--range",
+            f"{base}..HEAD",
+            env={"PYTHONUTF8": "0", "PYTHONCOERCECLOCALE": "0"},
+        )
+    )
+    _assert_accented_path(repo, out)
+
+
+def test_merge_churn_is_measured_and_counted(tmp_path):
+    repo, base = _merge_repo(tmp_path)
+    out = _json(_proc("--repo", str(repo), "--range", f"{base}..HEAD"))
+    assert out["commit_count"] == 4
+    assert out["merge_count"] == 2
+    assert out["merges_measured"] == 2
+    # Both merges' first-parent churn: 1/1 for the clean merge, 2/1 for the
+    # hand-resolved one (the resolution added a line neither branch had).
+    merge_files = {f["path"]: f for f in out["merge_files"]}
+    assert merge_files["s.py"]["added"] == 3
+    assert merge_files["s.py"]["deleted"] == 2
+    assert merge_files["s.py"]["net"] == 1
+    assert merge_files["s.py"]["commit_count"] == 2
+
+
+def test_merge_commits_listed_but_excluded_from_files(tmp_path):
+    repo, base = _merge_repo(tmp_path)
+    out = _json(_proc("--repo", str(repo), "--range", f"{base}..HEAD"))
+    by_subject = {c["subject"]: c for c in out["commits"]}
+    assert by_subject["merge story 1-2"]["is_merge"] is True
+    assert by_subject["merge story 1-3"]["is_merge"] is True
+    assert by_subject["epic-1-2 story one"]["is_merge"] is False
+    # `files` is the two story commits only — 1/1 each. Folding the merges in
+    # would double count: their diff restates the churn they merged.
+    files = {f["path"]: f for f in out["files"]}
+    assert files["s.py"]["added"] == 2
+    assert files["s.py"]["deleted"] == 2
+    assert files["s.py"]["commit_count"] == 2
+
+
+def test_story_attribution_survives_merges(tmp_path):
+    repo, base = _merge_repo(tmp_path)
+    out = _json(_proc("--repo", str(repo), "--range", f"{base}..HEAD", "--stories", "1-2,1-3"))
+    by_subject = {c["subject"]: c for c in out["commits"]}
+    assert by_subject["epic-1-2 story one"]["stories"] == ["1-2"]
+    assert by_subject["epic-1-3 story two"]["stories"] == ["1-3"]
+
+
+def test_off_spine_merge_is_counted_but_not_measured(tmp_path):
+    # A back-merge of the mainline into a story branch is a merge in the range,
+    # but its first-parent diff would restate unrelated mainline content as
+    # epic churn. It stays in merge_count and out of merges_measured, so the
+    # gap between the two says plainly that a merge went unmeasured.
+    repo = tmp_path / "repo"
+    repo.mkdir()
+    _git(repo, "init", "-q", "-b", "main")
+    (repo / "f.txt").write_text("base\n")
+    _git(repo, "add", "-A")
+    _git(repo, "commit", "-qm", "base")
+    base = _rev(repo, "HEAD")
+    (repo / "f.txt").write_text("base\nmain1\n")
+    _git(repo, "commit", "-qam", "mainline work")
+
+    _git(repo, "checkout", "-q", "-b", "s1", base)
+    (repo / "s1.txt").write_text("s1\n")
+    _git(repo, "add", "-A")
+    _git(repo, "commit", "-qm", "epic-1-2 story one")
+    _git(repo, "merge", "-q", "--no-ff", "main", "-m", "back-merge main into s1")
+    _git(repo, "checkout", "-q", "main")
+    _git(repo, "merge", "-q", "--no-ff", "s1", "-m", "merge story 1-2")
+
+    out = _json(_proc("--repo", str(repo), "--range", f"{base}..HEAD"))
+    assert out["merge_count"] == 2
+    assert out["merges_measured"] == 1
+    merge_files = {f["path"]: f for f in out["merge_files"]}
+    assert set(merge_files) == {"s1.txt"}
+
+
+def test_merge_pass_survives_a_hostile_log_diffmerges_config(tmp_path):
+    # `-m` means "whatever log.diffMerges says", so a user or repo config of
+    # `off` makes the merge pass emit no file rows: merge_files comes back
+    # empty beside a non-zero merges_measured and reads as "the merges changed
+    # nothing". The command-line -c pin beats the config.
+    repo, base = _merge_repo(tmp_path)
+    _git(repo, "config", "log.diffMerges", "off")
+    out = _json(_proc("--repo", str(repo), "--range", f"{base}..HEAD"))
+    assert out["merges_measured"] == 2
+    merge_files = {f["path"]: f for f in out["merge_files"]}
+    assert merge_files["s.py"]["added"] == 3
+    assert merge_files["s.py"]["deleted"] == 2
+
+
+def test_valid_range_with_no_commits_keeps_the_full_shape(tmp_path):
+    # A mis-specified epic range is a valid, empty range. It must still answer
+    # with every documented key rather than a differently-shaped stub.
+    repo = _make_repo(tmp_path)
+    proc = _proc("--repo", str(repo), "--range", "HEAD..HEAD")
+    out = _json(proc)
+    assert proc.returncode == 0
+    assert set(out) == {
+        "range",
+        "commit_count",
+        "merge_count",
+        "merges_measured",
+        "commits",
+        "files",
+        "merge_files",
+        "stories_supplied",
+    }
+    assert out["commit_count"] == 0
+    assert out["merge_count"] == 0
+    assert out["merges_measured"] == 0
+    assert out["commits"] == [] and out["files"] == [] and out["merge_files"] == []
+
+
+def test_linear_history_reports_no_merges(tmp_path):
+    repo = _make_repo(tmp_path)
+    out = _json(_proc("--repo", str(repo), "--range", "HEAD~1..HEAD"))
+    assert out["merge_count"] == 0
+    assert out["merges_measured"] == 0
+    assert out["merge_files"] == []
+
+
+def test_multi_story_subject_attributes_to_every_match(tmp_path):
+    # First-match-wins silently dropped the second story from the attribution.
+    repo = tmp_path / "repo"
+    repo.mkdir()
+    _git(repo, "init", "-q", "-b", "main")
+    (repo / "f.py").write_text("a\n")
+    _git(repo, "add", "-A")
+    _git(repo, "commit", "-qm", "base")
+    (repo / "f.py").write_text("a\nb\n")
+    _git(repo, "commit", "-qam", "fix seam between 1-2 and 1-3")
+
+    out = _json(_proc("--repo", str(repo), "--range", "HEAD~1..HEAD", "--stories", "1-3,1-2"))
+    # Every match, in --stories order — not whichever id was passed first.
+    assert out["commits"][0]["stories"] == ["1-3", "1-2"]
+
+    # A repeated id must not list the commit twice: any per-story total built
+    # from `stories` would count it twice.
+    repeated = _json(_proc("--repo", str(repo), "--range", "HEAD~1..HEAD", "--stories", "1-3,1-2,1-3"))
+    assert repeated["commits"][0]["stories"] == ["1-3", "1-2"]
+    assert repeated["stories_supplied"] == ["1-3", "1-2"]
+
+
+def test_subject_naming_no_story_gets_an_empty_list(tmp_path):
+    repo = tmp_path / "repo"
+    repo.mkdir()
+    _git(repo, "init", "-q", "-b", "main")
+    (repo / "f.py").write_text("a\n")
+    _git(repo, "add", "-A")
+    _git(repo, "commit", "-qm", "base")
+    (repo / "f.py").write_text("a\nb\n")
+    _git(repo, "commit", "-qam", "chore: tidy imports")
+
+    out = _json(_proc("--repo", str(repo), "--range", "HEAD~1..HEAD", "--stories", "1-2,1-3"))
+    assert out["commits"][0]["stories"] == []
+
+
+def _binary_repo(tmp_path):
+    """A binary-only path plus a path that is binary twice and text once."""
+    repo = tmp_path / "repo"
+    repo.mkdir()
+    _git(repo, "init", "-q", "-b", "main")
+    (repo / "keep.txt").write_text("keep\n")
+    _git(repo, "add", "-A")
+    _git(repo, "commit", "-qm", "base")
+    base = _rev(repo, "HEAD")
+
+    (repo / "src").mkdir()
+    (repo / "src" / "x.py").write_bytes(b"\x00\x01bin\n")
+    (repo / "blob.bin").write_bytes(b"\x00\x01blob\n")
+    _git(repo, "add", "-A")
+    _git(repo, "commit", "-qm", "add binary content")
+    (repo / "src" / "x.py").write_text("one\ntwo\n")  # binary -> text: still binary
+    _git(repo, "commit", "-qam", "x.py becomes text")
+    (repo / "src" / "x.py").write_text("one\ntwo\nthree\n")  # text -> text: measured
+    _git(repo, "commit", "-qam", "grow x.py")
+    (repo / "blob.bin").write_bytes(b"\x00\x02blob\n")
+    _git(repo, "commit", "-qam", "churn the blob")
+    return repo, base
+
+
+def test_binary_revisions_no_longer_erase_measured_text_churn(tmp_path):
+    repo, base = _binary_repo(tmp_path)
+    out = _json(_proc("--repo", str(repo), "--range", f"{base}..HEAD"))
+    x = {f["path"]: f for f in out["files"]}["src/x.py"]
+    assert x["added"] == 1 and x["deleted"] == 0 and x["net"] == 1
+    assert x["binary_revisions"] == 2
+    assert x["commit_count"] == 3
+
+
+def test_binary_only_path_reports_zero_sums_and_its_revision_count(tmp_path):
+    repo, base = _binary_repo(tmp_path)
+    out = _json(_proc("--repo", str(repo), "--range", f"{base}..HEAD"))
+    blob = {f["path"]: f for f in out["files"]}["blob.bin"]
+    assert blob["added"] == 0 and blob["deleted"] == 0 and blob["net"] == 0
+    assert blob["binary_revisions"] == 2
+    assert blob["commit_count"] == 2
+
+
+def test_success_shape_carries_every_documented_key(tmp_path):
+    repo = _make_repo(tmp_path)
+    out = _json(_proc("--repo", str(repo), "--range", "HEAD~1..HEAD"))
+    assert set(out) >= {
+        "range",
+        "commit_count",
+        "merge_count",
+        "merges_measured",
+        "commits",
+        "files",
+        "merge_files",
+        "stories_supplied",
+    }
+    assert set(out["commits"][0]) == {"sha", "subject", "stories", "is_merge"}
+    assert set(out["files"][0]) == {
+        "path",
+        "added",
+        "deleted",
+        "net",
+        "commit_count",
+        "binary_revisions",
+    }
+
+
+def test_explicit_repo_ignores_ambient_git_dir(tmp_path):
+    repo = _make_repo(tmp_path)
+    proc = _proc(
+        "--repo",
+        str(repo),
+        "--range",
+        "HEAD~1..HEAD",
+        env={"GIT_DIR": str(tmp_path / "wrong-git-dir")},
+    )
+    assert _json(proc)["commit_count"] == 1
+
+
+if __name__ == "__main__":
+    sys.exit(pytest.main([__file__, "-q"]))