tests: kdoc: fix handling file removal

Looks like the kdoc test struggles with file deletion
as well as files which produce no warnings at all.
Fix that. Add more logs for ease of troubleshooting.

While at it shorten the outputs a little bit
to make the summary fit on a line when running ingest_mdir

Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Author: kuba-moo

tests/patch/kdoc/test.py

@@ -72,7 +72,7 @@ def from_text(self, line, extra=None):
     def __str__(self):
         return self.message
 
-def parse_warnings(lines) -> List[KdocWarning]:
+def parse_warnings(lines, logs) -> List[KdocWarning]:
     skip = False
     length = len(lines)
 
@@ -87,16 +87,24 @@ def parse_warnings(lines) -> List[KdocWarning]:
         if line.endswith(':') and i + 1 < length:
             extra = lines[i + 1]
             skip = True
+        elif not line.strip():
+            continue
         else:
+            logs += ["<parse fail>: " + line.strip()]
             extra = None
 
         warnings.append(KdocWarning.from_text(line, extra))
 
     return warnings
 
-def run_kernel_doc(tree, commitish, files) -> List[KdocWarning]:
+def run_kernel_doc(tree, commitish, files, logs) -> List[KdocWarning]:
     """ Run ./scripts/kdoc on a given commit and capture its results. """
 
+    logs += ["files: " + str(files)]
+
+    if not files:
+        return []
+
     cmd = ["git", "checkout", "-q", commitish]
     subprocess.run(cmd, cwd=tree.path, capture_output=False, check=True)
 
@@ -106,13 +114,13 @@ def run_kernel_doc(tree, commitish, files) -> List[KdocWarning]:
 
     lines = result.stderr.strip().split('\n')
 
-    return parse_warnings(lines)
+    return parse_warnings(lines, logs)
 
 def extract_files(patch):
     """Extract paths added or modified by the patch."""
 
-    all_files = set()
-    mod_files = set()
+    before_files = set()
+    after_files = set()
     lines = patch.raw_patch.split("\n")
 
     # Walk lines, skip last since it doesn't have next
@@ -124,19 +132,19 @@ def extract_files(patch):
 
         file_path = next_line[6:]
 
-        all_files.add(file_path)
-
-        if line != "--- /dev/null":
-            mod_files.add(file_path)
+        if "/dev/null" not in line:
+            before_files.add(file_path)
+        if "/dev/null" not in next_line:
+            after_files.add(file_path)
 
-    return list(mod_files), list(all_files)
+    return list(before_files), list(after_files)
 
 def kdoc(tree, patch, _result_dir) -> Tuple[int, str, str]:
     """ Main function / entry point """
 
-    mod_files, all_files = extract_files(patch)
+    before_files, after_files = extract_files(patch)
 
-    if not mod_files or not all_files:
+    if not before_files and not after_files:
         return 1, "Patch has no modified files?", ""
 
     ret = 0
@@ -146,12 +154,12 @@ def kdoc(tree, patch, _result_dir) -> Tuple[int, str, str]:
     head_commit = get_git_head(tree)
 
     try:
-        incumbent_warnings = run_kernel_doc(tree, "HEAD~", mod_files)
         log += ["Warnings before patch:"]
+        incumbent_warnings = run_kernel_doc(tree, "HEAD~", before_files, log)
         log.extend(map(str, incumbent_warnings))
 
-        current_warnings = run_kernel_doc(tree, head_commit, all_files)
         log += ["", "Current warnings:"]
+        current_warnings = run_kernel_doc(tree, head_commit, after_files, log)
         log.extend(map(str, current_warnings))
     except subprocess.CalledProcessError as e:
         desc = f'{e.cmd} failed with exit code {e.returncode}'
@@ -173,11 +181,14 @@ def kdoc(tree, patch, _result_dir) -> Tuple[int, str, str]:
     new_count = len(new_warnings)
     rm_count = len(rm_warnings)
 
-    desc = f'Errors and warnings before: {incumbent_count} This patch: {current_count}'
+    desc = f'Warnings before: {incumbent_count} after: {current_count}'
+    brac = []
     if new_count:
-        desc += f' New: {new_count}'
+        brac += [f'add: {new_count}']
     if rm_count:
-        desc += f' Removed: {rm_count}'
+        brac += [f'del: {rm_count}']
+    if brac:
+        desc += f' ({" ".join(brac)})'
     log += ["", desc]
 
     if rm_count: