fix: when FileCreationTime is blank use 0000

file.go

@@ -456,6 +456,17 @@ func (f *File) setBatchesFromJSON(bs []byte) error {
 // values which are not in their ACH format (YYMMDD, hhmm). It'll attempt to parse
 // various formats and overwrite them to the expected values (YYMMDD, hhmm).
 func (f *File) overwriteDateTimeFields() {
+	// Sometimes FileCreationTime is empty but FileCreationDate is populated, so set Time to 0000
+	if f.Header.FileCreationDate != "" && f.Header.FileCreationTime == "" {
+		f.Header.FileCreationTime = "0000"
+	}
+	// If both Date and Time are empty use the current wall clock value
+	if f.Header.FileCreationDate == "" && f.Header.FileCreationTime == "" {
+		now := time.Now()
+		f.Header.FileCreationTime = now.Format("1504")
+		f.Header.FileCreationDate = now.Format("060102")
+	}
+
 	// File header
 	if t, err := datetimeParse(f.Header.FileCreationDate); err == nil {
 		f.Header.FileCreationDate = t.Format("060102")

file_test.go

@@ -19,6 +19,7 @@ package ach
 
 import (
 	"bytes"
+	"cmp"
 	"encoding/json"
 	"fmt"
 	"io"
@@ -503,7 +504,7 @@ func TestFileReadJSONFile(t *testing.T) {
 	if file.Header.ImmediateDestination != "231380104" || file.Header.ImmediateDestinationName != "Citadel" {
 		t.Errorf("destination=%s name=%s", file.Header.ImmediateDestination, file.Header.ImmediateDestinationName)
 	}
-	if file.Header.FileCreationTime != "" || file.Header.FileCreationDate != "181008" {
+	if file.Header.FileCreationTime != "0000" || file.Header.FileCreationDate != "181008" {
 		t.Errorf("time=%v date=%v", file.Header.FileCreationTime, file.Header.FileCreationDate)
 	}
 	if v := file.Header.FileCreationTimeField(); v == "" || len(v) != 4 {
@@ -610,6 +611,64 @@ func TestFile__jsonFileNoControlBlobs(t *testing.T) {
 	}
 }
 
+func TestFile_overwriteDateTimeFields(t *testing.T) {
+	now := time.Now()
+
+	cases := []struct {
+		fileCreationDate string
+		fileCreationTime string
+
+		expectedFileCreationDate string
+		expectedFileCreationTime string
+	}{
+		{
+			fileCreationDate: "",
+			fileCreationTime: "",
+
+			expectedFileCreationDate: now.Format("060102"),
+			expectedFileCreationTime: now.Format("1504"),
+		},
+		{
+			fileCreationDate: strings.Repeat(" ", 6),
+			fileCreationTime: strings.Repeat(" ", 4),
+
+			expectedFileCreationDate: strings.Repeat(" ", 6),
+			expectedFileCreationTime: strings.Repeat(" ", 4),
+		},
+		{
+			fileCreationDate: "261230",
+			fileCreationTime: "",
+
+			expectedFileCreationDate: "261230",
+			expectedFileCreationTime: "0000",
+		},
+		{
+			fileCreationDate: "261230",
+			fileCreationTime: "1234",
+
+			expectedFileCreationDate: "261230",
+			expectedFileCreationTime: "1234",
+		},
+	}
+	for _, tc := range cases {
+		name := fmt.Sprintf("%s at %s", cmp.Or(tc.fileCreationDate, "empty"), cmp.Or(tc.fileCreationTime, "empty"))
+
+		t.Run(name, func(t *testing.T) {
+			file := mockFilePPD(t)
+			file.Header.FileCreationDate = tc.fileCreationDate
+			file.Header.FileCreationTime = tc.fileCreationTime
+
+			file.overwriteDateTimeFields()
+
+			require.Equal(t, tc.expectedFileCreationDate, file.Header.FileCreationDate)
+			require.Equal(t, tc.expectedFileCreationDate, file.Header.FileCreationDateField())
+
+			require.Equal(t, tc.expectedFileCreationTime, file.Header.FileCreationTime)
+			require.Equal(t, tc.expectedFileCreationTime, file.Header.FileCreationTimeField())
+		})
+	}
+}
+
 func TestFile__rfc3339JSON(t *testing.T) {
 	bs, err := os.ReadFile(filepath.Join("test", "testdata", "rfc3339.json"))
 	if err != nil {