results: Bail out gracefully when profile data is missing

asv/results.py

@@ -549,11 +549,22 @@ def get_profile(self, benchmark_name):
 
         Returns
         -------
-        profile_data : pstats.Stats
-            Profile data
+        profile_data : bytes
+            Raw profile data. Use `get_profile_stats` for a `pstats.Stats`
+            object.
+
+        Raises
+        ------
+        UserError
+            If no profile was stored for the benchmark.
 
         """
-        profile_data = self._profiles[benchmark_name]
+        profile_data = self._profiles.get(benchmark_name)
+        if not profile_data:
+            raise util.UserError(
+                f"No profile data available for benchmark '{benchmark_name}'. "
+                f"Re-run the benchmark with --profile to collect it."
+            )
         profile_data = profile_data.encode('ascii')
         profile_bytes = zlib.decompress(base64.b64decode(profile_data))
         return profile_bytes

changelog.d/1614.bugfix.rst

@@ -0,0 +1 @@
+Raise a clear error from ``Results.get_profile`` when no profile data was stored, instead of ``KeyError`` or ``AttributeError`` (#1459).

test/test_profile.py

@@ -75,3 +75,20 @@ def test_profile_python_commit(capsys, basic_conf):
     text, err = capsys.readouterr()
 
     assert "Profile data does not already exist" not in text
+
+
+def test_get_profile_missing_data():
+    # A benchmark with no stored profile should report that clearly instead of
+    # raising KeyError or AttributeError from inside get_profile.
+    from asv.results import Results
+
+    results = Results.unnamed()
+
+    with pytest.raises(util.UserError, match="No profile data available"):
+        results.get_profile("time_absent")
+
+    # add_result only stores a profile when it is truthy, so a falsy entry is
+    # reachable too.
+    results._profiles["time_nulled"] = None
+    with pytest.raises(util.UserError, match="No profile data available"):
+        results.get_profile("time_nulled")