refactor: we don't need a check for v4 data files anymore

nedbat · nedbat · commit 2ecaf7211ad6 · 2025-12-13T09:52:07.000-05:00
diff --git a/coverage/sqlitedb.py b/coverage/sqlitedb.py
@@ -127,19 +127,6 @@ def _execute(self, sql: str, parameters: Iterable[Any]) -> sqlite3.Cursor:
                 return self.con.execute(sql, parameters)  # type: ignore[arg-type]
         except sqlite3.Error as exc:
             msg = str(exc)
-            if not self.no_disk:
-                try:
-                    # `execute` is the first thing we do with the database, so try
-                    # hard to provide useful hints if something goes wrong now.
-                    with open(self.filename, "rb") as bad_file:
-                        cov4_sig = b"!coverage.py: This is a private format"
-                        if bad_file.read(len(cov4_sig)) == cov4_sig:
-                            msg = (
-                                "Looks like a coverage 4.x data file. "
-                                + "Are you mixing versions of coverage?"
-                            )
-                except Exception:
-                    pass
             if self.debug.should("sql"):
                 self.debug.write(f"EXCEPTION from execute: {exc_one_line(exc)}")
             raise DataError(f"Couldn't use data file {self.filename!r}: {msg}") from exc
diff --git a/tests/test_api.py b/tests/test_api.py
@@ -23,7 +23,7 @@
 import coverage
 from coverage import Coverage, env
 from coverage.data import line_counts, sorted_lines
-from coverage.exceptions import ConfigError, CoverageException, DataError, NoDataError, NoSource
+from coverage.exceptions import ConfigError, CoverageException, NoDataError, NoSource
 from coverage.files import abs_file, relative_filename
 from coverage.misc import import_local_file
 from coverage.types import FilePathClasses, FilePathType, TCovKwargs
@@ -355,17 +355,6 @@ def test_completely_zero_reporting(self) -> None:
         last = self.last_line_squeezed(self.stdout())
         assert "TOTAL 1 1 0%" == last
 
-    def test_cov4_data_file(self) -> None:
-        cov4_data = (
-            "!coverage.py: This is a private format, don't read it directly!"
-            + '{"lines":{"/somewhere/not/really.py":[1,5,2,3]}}'
-        )
-        self.make_file(".coverage", cov4_data)
-        cov = coverage.Coverage()
-        with pytest.raises(DataError, match="Looks like a coverage 4.x data file"):
-            cov.load()
-        cov.erase()
-
     def make_code1_code2(self) -> None:
         """Create the code1.py and code2.py files."""
         self.make_file(
