MRG: fix output for sketch ... --singleton (#3066)

Fixes #2819

---------

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

src/sourmash/command_compute.py

@@ -204,6 +204,7 @@ def _compute_individual(args, signatures_factory):
 
             # make a new signature for each sequence?
             if args.singleton:
+                n_calculated = 0
                 for n, record in enumerate(screed_iter):
                     sigs = signatures_factory()
                     try:
@@ -218,12 +219,13 @@ def _compute_individual(args, signatures_factory):
                         error(str(exc))
                         sys.exit(-1)
 
+                    n_calculated += len(sigs)
                     set_sig_name(sigs, filename, name=record.name)
                     save_sigs_to_location(sigs, save_sigs)
 
                 notify(
                     "calculated {} signatures for {} sequences in {}",
-                    len(save_sigs),
+                    n_calculated,
                     n + 1,
                     filename,
                 )

tests/test_sourmash_sketch.py

@@ -1393,6 +1393,7 @@ def test_do_sourmash_singleton_multiple_files_no_out_specified(runtmp):
         "saved 2 signature(s) to 'shewanella.faa.sig'. Note: signature license is CC0."
         in runtmp.last_result.err
     )
+    assert "calculated 2 signatures for 2 sequences in" in runtmp.last_result.err
 
     sig1 = runtmp.output("ecoli.faa.sig")
     assert os.path.exists(sig1)
@@ -1441,6 +1442,8 @@ def test_do_sourmash_singleton_multiple_files_output(runtmp):
         "saved 4 signature(s) to 'output.sig'. Note: signature license is CC0."
         in runtmp.last_result.err
     )
+    assert "calculated 2 signatures for 2 sequences in" in runtmp.last_result.err
+    assert "calculated 4 signatures for 2 sequences in" not in runtmp.last_result.err
 
     sig1 = runtmp.output("output.sig")
     assert os.path.exists(sig1)