On fails, extract the lines with the failure marker >> from the logfile

build_pr_changes.py

@@ -833,7 +833,40 @@ def main(args) -> int:
     return build_and_act_on_results(args, installed, specs_to_check)
 
 
-def generate_build_results(installed, passed, failed, about_build_host) -> str:
+def failure_summary(fails: List[Tuple[str, str]]) -> str:
+    """Generate a summary of the failed specs."""
+    if not fails:
+        return ""
+
+    fails_summary = f"{len(fails)} failed specs:" if len(fails) > 1 else "One failed spec:"
+    for failed_spec, _ in fails:
+        fails_summary += f"- `{failed_spec}`\n"
+
+    for failed_spec, log_file in fails:
+        fails_summary += f"### `{failed_spec}`:\n```py\n"
+        with open(log_file, "r", encoding="utf-8") as log:
+            lines = log.readlines()
+            # Print one line before lines with the error marker as well:
+            previous_line = ""
+            for line in lines:
+                if r"[0;91m>> " in line:  # Match the color code and error marker.
+                    fails_summary += previous_line
+                    fails_summary += line
+                    previous_line = ""
+                else:
+                    previous_line = line
+            fails_summary += ("".join(lines)).strip()
+        fails_summary += "\n```\n"
+        if "failed to concretize" in lines[0]:
+            fails_summary += "spack failed to concretize specs due to conflicts.\nThis is"
+            fails_summary += " likely intentional due to a conflict() in the recipe(s).\n"
+
+    # TODO: Add support for showing details about the failed specs
+    # like used deps (cmake version, openssl version, etc.)
+    return fails_summary
+
+
+def generate_build_results(installed, passed, fails, about_build_host) -> str:
     """Generate a report in markdown format for cut-and-paste into the PR comment."""
 
     build_results = f"\nBuild results{about_build_host}:\n```py\n"
@@ -851,32 +884,8 @@ def generate_build_results(installed, passed, failed, about_build_host) -> str:
             build_results += stdout.replace(" build_system=python_pip", "")
         else:
             build_results += stderr or stdout
-    build_results += "\n```\n"
-    if failed:
-        title = f"{len(failed)} failed specs:" if len(failed) > 1 else "One failed spec:"
-        build_results += f"\n## {title}\n"
-        for failed_spec, _ in failed:
-            build_results += f"- `{failed_spec}`\n"
-
-        for failed_spec, log_file in failed:
-            build_results += f"### `{failed_spec}`:\n```py\n"
-            # Read log file, look for "found in build log" and add the lines after it.
-            with open(log_file, "r", encoding="utf-8") as log:
-                lines = log.readlines()
-                for line in lines:
-                    if "found in build log" in line:
-                        build_results += line
-                        build_results += "".join(lines[lines.index(line) + 8 : -8])
-                        break
-                build_results += ("".join(lines)).strip()
-            build_results += "\n```\n"
-            if "failed to concretize" in lines[0]:
-                build_results += "spack failed to concretize the spec due to a conflict.\nThis is"
-                build_results += " likely intentional due to a conflict() in the recipe(s).\n"
-
-        # TODO: Add support for showing details about the failed specs
-        # like used deps (cmake version, openssl version, etc.)
 
+    build_results += "\n```\n" + failure_summary(fails)
     build_results += "\nGenerated by "
     git_dir = os.path.dirname(os.path.realpath(__file__))
     err, stdout, stderr = run(["git", "-C", git_dir, "config", "--get", "remote.origin.url"])