1 files changed, 23 insertions, 1 deletions
diff --git a/coverage/data.py b/coverage/data.py
index c70993ad..2765c4a3 100644
--- a/coverage/data.py
+++ b/coverage/data.py
@@ -14,7 +14,7 @@ import glob
 import os.path
 
 from coverage.exceptions import CoverageException, NoDataError
-from coverage.misc import file_be_gone
+from coverage.misc import file_be_gone, human_sorted, plural
 from coverage.sqldata import CoverageData
 
 
@@ -139,3 +139,25 @@ def combine_parallel_data(
 
     if strict and not files_combined:
         raise NoDataError("No usable data files")
+
+
+def debug_data_file(filename):
+    """Implementation of 'coverage debug data'."""
+    data = CoverageData(filename)
+    filename = data.data_filename()
+    print(f"path: {filename}")
+    if not os.path.exists(filename):
+        print("No data collected: file doesn't exist")
+        return
+    data.read()
+    print(f"has_arcs: {data.has_arcs()!r}")
+    summary = line_counts(data, fullpath=True)
+    filenames = human_sorted(summary.keys())
+    nfiles = len(filenames)
+    print(f"{nfiles} file{plural(nfiles)}:")
+    for f in filenames:
+        line = f"{f}: {summary[f]} line{plural(summary[f])}"
+        plugin = data.file_tracer(f)
+        if plugin:
+            line += f" [{plugin}]"
+        print(line)