db: report hidden asset count in malformed-ip warning suffix

malformedIPAssetWarning appended "and N more" with N = total, the number
of offending assets, instead of the number left out of the sample. With 8
bad rows and 5 named it read "... and 8 more"; it now reads "... and 3
more". Same bug as the one fixed in notify/render.go.

Move the wording into malformedIPAssetWarningText so it can be tested
without Postgres, and add a test for the 8-of-5 and 5-of-5 cases.

db/companies.go

@@ -633,14 +633,20 @@ LIMIT $1`, malformedIPAssetsSampled)
 	if total == 0 {
 		return "", nil
 	}
+	return malformedIPAssetWarningText(total, samples), nil
+}
+
+// malformedIPAssetWarningText words the warning for total offending assets, of
+// which only samples are named; the ones left out are counted in the suffix.
+func malformedIPAssetWarningText(total int, samples []string) string {
 	warning := fmt.Sprintf(
 		"%d assets have an ip field that is not a valid IP; skipped for IP/CIDR scope matching (these assets will not be attributed to a company by subnet rules): %s",
 		total, strings.Join(samples, ", "),
 	)
 	if total > len(samples) {
-		warning += fmt.Sprintf(" and %d more", total)
+		warning += fmt.Sprintf(" and %d more", total-len(samples))
 	}
-	return warning, nil
+	return warning
 }
 
 // UpdateScope replaces all scope rules for a company and reattributes.

db/companies_test.go

@@ -458,3 +458,21 @@ func TestListCompanies(t *testing.T) {
 		t.Error("ListCompanies: created company not found")
 	}
 }
+
+func TestMalformedIPAssetWarningTextCountsOmitted(t *testing.T) {
+	samples := []string{"#1 a", "#2 b", "#3 c", "#4 d", "#5 e"}
+	// The suffix must count the assets left out, not repeat the total, otherwise
+	// the operator is told about more bad rows than exist.
+	got := malformedIPAssetWarningText(8, samples)
+	if !strings.HasPrefix(got, "8 assets have an ip field") {
+		t.Fatalf("the warning should lead with the total of 8, got %q", got)
+	}
+	if !strings.HasSuffix(got, ": #1 a, #2 b, #3 c, #4 d, #5 e and 3 more") {
+		t.Fatalf("8 assets with 5 named should note the 3 omitted, got %q", got)
+	}
+	// When every offending asset is named there is nothing to add.
+	got = malformedIPAssetWarningText(5, samples)
+	if !strings.HasSuffix(got, ": #1 a, #2 b, #3 c, #4 d, #5 e") {
+		t.Fatalf("5 assets with 5 named should have no suffix, got %q", got)
+	}
+}