go modules; fix test

go.mod

@@ -0,0 +1 @@
+module github.com/richardlehane/msoleps

msoleps_test.go

@@ -16,15 +16,15 @@ func testFile(t *testing.T, path string) *Reader {
 	defer file.Close()
 	doc, err := NewFrom(file)
 	if err != nil {
-		t.Errorf("Error opening file; Returns error: ", err)
+		t.Errorf("Error opening file; Returns error: %v", err)
 	}
 	return doc
 }
 
 func TestDocSum(t *testing.T) {
 	doc := testFile(t, testDocSum)
 	if len(doc.Property) != 12 {
-		t.Error("Expecting 12 properties, got %d", len(doc.Property))
+		t.Errorf("Expecting 12 properties, got %d", len(doc.Property))
 	}
 	if doc.Property[1].String() != "Australian Broadcasting Corporation" {
 		t.Errorf("Expecting 'ABC' as second property, got %s", doc.Property[1])
@@ -34,7 +34,7 @@ func TestDocSum(t *testing.T) {
 func TestSum(t *testing.T) {
 	doc := testFile(t, testSum)
 	if len(doc.Property) != 17 {
-		t.Error("Expecting 17 properties, got %d", len(doc.Property))
+		t.Errorf("Expecting 17 properties, got %d", len(doc.Property))
 	}
 	if doc.Property[5].String() != "Normal" {
 		t.Errorf("Expecting 'Normal' as sixth property, got %s", doc.Property[5])
@@ -44,7 +44,7 @@ func TestSum(t *testing.T) {
 func TestSum1(t *testing.T) {
 	doc := testFile(t, testSum1)
 	if len(doc.Property) != 3 {
-		t.Error("Expecting 3 properties, got %d", len(doc.Property))
+		t.Errorf("Expecting 3 properties, got %d", len(doc.Property))
 	}
 	if doc.Property[0].String() != "Mail" {
 		t.Errorf("Expecting 'Mail' as first property, got %s", doc.Property[0])