Fix formatter crashing on empty Jobs.

python/lsst/verify/bin/inspectjob.py

@@ -77,6 +77,28 @@ def _simplify_key(key, prefix):
         return key
 
 
+def _get_first_col_width(job):
+    """Return the width to use for the output's first column.
+
+    This column displays metadata and metric keys.
+
+    Parameters
+    ----------
+    job : `lsst.verify.Job`
+        The Job to print.
+
+    Returns
+    -------
+    The minimum width to use to format the Job's values. May be 0 if the Job
+    is empty.
+    """
+    max_meta = max(len(key) for key in job.meta) if job.meta else 0
+    max_meas = max(len(str(metric)) for metric in job.measurements) \
+        if job.measurements else 0
+
+    return max(max_meta, max_meas)
+
+
 def inspect_job(job):
     """Present the measurements in a Job object.
 
@@ -88,7 +110,7 @@ def inspect_job(job):
         The Job to examine.
     """
     # Leave enough space for output so that all '=' characters are aligned
-    max_metric_length = max([len(str(metric)) for metric in job.measurements])
+    max_metric_length = _get_first_col_width(job)
 
     print("Common metadata:")
     for key, value in job.meta.items():

tests/test_inspectjob.py

@@ -140,6 +140,63 @@ def test_specs(self, mock_stdout):
         """
         self.assertNotIn("utterly_ridiculous", mock_stdout.getvalue())
 
+    def test_empty(self, mock_stdout):
+        """Test that inspect_job can handle files with neither metrics nor metadata.
+        """
+        inspect_job(Job())
+        # No specific output expected, so test passes if inspect_job
+        # didn't raise.
+
+    def test_metadataonly(self, mock_stdout):
+        """Test that inspect_job can handle files with metadata but no metrics.
+        """
+        # Job and its components were not designed to support deletion, so
+        # create a new Job from scratch to ensure it's a valid object.
+        job = Job()
+        job.metrics.insert(Metric("foo.boringmetric", "",
+                                  u.percent,
+                                  tags=["redundant"]))
+        job.metrics.insert(Metric("foo.fancymetric", "",
+                                  u.meter,
+                                  tags=["vital"]))
+        job.meta["bar"] = "high"
+        job.meta["shape"] = "rotund"
+        job.specs.insert(ThresholdSpecification("utterly_ridiculous",
+                                                1e10 * u.meter,
+                                                ">"))
+
+        inspect_job(job)
+        output = mock_stdout.getvalue()
+        for key, value in [("bar", "high"),
+                           ("shape", "rotund")]:
+            self._check_metadata(key, value, output)
+
+    def test_metricsonly(self, mock_stdout):
+        """Test that inspect_job can handle files with metrics but no metadata.
+        """
+        # Job and its components were not designed to support deletion, so
+        # create a new Job from scratch to ensure it's a valid object.
+        job = Job()
+        job.metrics.insert(Metric("foo.boringmetric", "",
+                                  u.percent,
+                                  tags=["redundant"]))
+        job.metrics.insert(Metric("foo.fancymetric", "",
+                                  u.meter,
+                                  tags=["vital"]))
+        job.measurements.insert(Measurement("foo.fancymetric",
+                                            2.0 * u.meter))
+        job.measurements.insert(Measurement("foo.fanciermetric",
+                                            3.5 * u.second))
+        job.measurements["foo.fanciermetric"].notes["fanciness"] = "moderate"
+        job.measurements.insert(Measurement("foo.fanciestmetric",
+                                            3.1415927 * u.kilogram))
+
+        inspect_job(job)
+        output = mock_stdout.getvalue()
+        # MeasurementSet.values does not exist
+        for _, measurement in job.measurements.items():
+            self._check_measurement(measurement, output)
+
 
 if __name__ == "__main__":
     unittest.main()