test(cli, download): add 17 gap-coverage tests for Phase 7

CLI: clear-cache (existing + missing), path (ok + error), fetch happy
path, no/unknown subcommand error paths. Calls cli.main() directly
instead of subprocess to keep tests fast and capture stderr cleanly.

Download: cache hit skips HTTP, tar.gz extraction, comment/blank
checksum lines, unknown archive format, missing entry after extract,
unsupported platform. Also covers pure helpers _parse_owner_repo,
_sha256_file, and _github_token env precedence.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

tests/test_cli.py

@@ -1,8 +1,11 @@
 import subprocess
 import sys
+from pathlib import Path
 
 import pytest
 
+from invisible_playwright import cli
+
 
 @pytest.mark.unit
 def test_version_subcommand():
@@ -24,3 +27,96 @@ def test_help_subcommand():
     assert "fetch" in r.stdout
     assert "path" in r.stdout
     assert "clear-cache" in r.stdout
+
+
+# CL1: clear-cache with existing cache prints "removed:" + path
+@pytest.mark.unit
+def test_clear_cache_with_existing_cache(tmp_path, monkeypatch, capsys):
+    cache = tmp_path / "existing-cache"
+    cache.mkdir()
+    (cache / "marker").write_text("x")
+    monkeypatch.setattr("invisible_playwright.cli.cache_root", lambda: cache)
+
+    rc = cli.main(["clear-cache"])
+
+    captured = capsys.readouterr()
+    assert rc == 0
+    assert captured.out.startswith("removed:")
+    assert str(cache) in captured.out
+    assert not cache.exists()
+
+
+# CL2: clear-cache with no cache prints "nothing to remove:"
+@pytest.mark.unit
+def test_clear_cache_with_no_cache(tmp_path, monkeypatch, capsys):
+    cache = tmp_path / "missing-cache"
+    assert not cache.exists()
+    monkeypatch.setattr("invisible_playwright.cli.cache_root", lambda: cache)
+
+    rc = cli.main(["clear-cache"])
+
+    captured = capsys.readouterr()
+    assert rc == 0
+    assert captured.out.startswith("nothing to remove:")
+    assert str(cache) in captured.out
+
+
+# CL3: path when binary exists prints path, exit 0
+@pytest.mark.unit
+def test_path_subcommand_when_binary_exists(tmp_path, monkeypatch, capsys):
+    fake_binary = tmp_path / "firefox.exe"
+    fake_binary.write_text("x")
+    monkeypatch.setattr("invisible_playwright.cli.ensure_binary", lambda: fake_binary)
+
+    rc = cli.main(["path"])
+
+    captured = capsys.readouterr()
+    assert rc == 0
+    assert str(fake_binary) in captured.out
+    assert captured.err == ""
+
+
+# CL4: path when binary missing prints to stderr, exit 1
+@pytest.mark.unit
+def test_path_subcommand_when_binary_missing(monkeypatch, capsys):
+    def boom():
+        raise RuntimeError("download failed")
+    monkeypatch.setattr("invisible_playwright.cli.ensure_binary", boom)
+
+    rc = cli.main(["path"])
+
+    captured = capsys.readouterr()
+    assert rc == 1
+    assert "error:" in captured.err
+    assert "download failed" in captured.err
+    assert captured.out == ""
+
+
+# CL5: no subcommand → argparse error, exit != 0
+@pytest.mark.unit
+def test_no_subcommand_errors():
+    with pytest.raises(SystemExit) as exc_info:
+        cli.main([])
+    assert exc_info.value.code != 0
+
+
+# CL6: unknown subcommand → argparse error
+@pytest.mark.unit
+def test_unknown_subcommand_errors():
+    with pytest.raises(SystemExit) as exc_info:
+        cli.main(["bogus"])
+    assert exc_info.value.code != 0
+
+
+# Extra: fetch happy path with mocked ensure_binary
+@pytest.mark.unit
+def test_fetch_subcommand_prints_path(tmp_path, monkeypatch, capsys):
+    fake_binary = tmp_path / "firefox.exe"
+    fake_binary.write_text("x")
+    monkeypatch.setattr("invisible_playwright.cli.ensure_binary", lambda: fake_binary)
+
+    rc = cli.main(["fetch"])
+
+    captured = capsys.readouterr()
+    assert rc == 0
+    assert str(fake_binary) in captured.out