[MRG] add test to confirm failure when summarizing on empty gather

tests/test_tax.py

@@ -745,19 +745,55 @@ def test_label_0(runtmp):
     assert "d__Bacteria;p__Bacteroidota;c__Bacteroidia;o__Bacteroidales;f__Bacteroidaceae;g__Phocaeicola;s__Phocaeicola vulgatus" in lin_gather_results[3]
     assert "d__Bacteria;p__Bacteroidota;c__Bacteroidia;o__Bacteroidales;f__Bacteroidaceae;g__Prevotella;s__Prevotella copri" in lin_gather_results[4]
 
-## some test ideas to start with -- see test_lca.py for add'l ideas
+def test_summarize_empty_gather_results(runtmp):
+    tax = utils.get_test_data('tax/test.taxonomy.csv')
+
+    #creates empty gather result
+    g_csv = runtmp.output('g.csv')
+    with open(g_csv, "w") as fp:
+        fp.write("")
+    print("g_csv: ", g_csv)
+
+    #test below is not working properly: assert statement needs to be moved outside of the with block, but exc.value is empty and im not sure why
+    with pytest.raises(ValueError) as exc:
+        #should fail
+        runtmp.run_sourmash('tax', 'summarize', g_csv, '--taxonomy-csv', tax)
+    print("exc.val= ", str(exc.value))
+    assert "No gather results loaded from "+g_csv in str(exc.value)
+
+    assert runtmp.last_result.status == -1
+
+
+def test_summarize_empty_tax_lineage_input(runtmp):
+#    print(type(runtmp))
+    tax_empty = runtmp.output('t.csv')
+    outcsv = runtmp.output('out.csv')
+    g_csv = utils.get_test_data('tax/test1.gather.csv')
+
+    with open(tax_empty, "w") as fp:
+        fp.write("")
+    print("t_csv: ", tax_empty)
+    import sys
+
+    with pytest.raises(ValueError) as exc:
+        runtmp.run_sourmash('tax', 'summarize', g_csv, '--taxonomy-csv', tax_empty, '--split-identifiers', '-o', outcsv)
+    print(f"----------------- [DEBUG]{exc.value}", file=sys.stderr)
+    if(str(exc.value) == "local variable 'n' referenced before assignment"):
+        print("[DEBUG] -------------------- PASSED")
+    else:
+        print("FAIL")
+
+    print(runtmp.last_result.status)
+    print(runtmp.last_result.out)
+    print(runtmp.last_result.err)
+
+    assert runtmp.last_result.status != 0 
+
 
-#def test_summarize_empty_gather_results():
-#    pass
-#def test_summarize_bad_gather_results():
-#    pass
-#def test_summarize_empty_lineage_input():
-#    pass
 #def test_summarize_bad_lineage_input():
 #    pass
 #def test_summarize_bad_rank():
 #    pass
-#
 #def test_classify_bad_gather_results():
 #    pass
 #def test_classify_bad_lineage_input():