track 2 spec added (#314)

Co-authored-by: wisely11 <wisely.samuel@gmail.com>

examples/fields/track2.json

@@ -0,0 +1,12 @@
+{
+    "name": "ISO 8583 v1987 Track2",
+    "fields": {
+        "35": {
+            "type": "Track2",
+            "length": 37,
+            "description": "TRACK 2 DATA",
+            "prefix": "Binary.L",
+            "enc": "ASCIIToHex"            
+        }
+    }
+}

specs/builder.go

@@ -24,6 +24,7 @@ type FieldConstructorFunc func(spec *field.Spec) field.Field
 var (
 	FieldConstructor = map[string]FieldConstructorFunc{
 		"String":    func(spec *field.Spec) field.Field { return field.NewString(spec) },
+		"Track2":    func(spec *field.Spec) field.Field { return field.NewTrack2(spec) },
 		"Numeric":   func(spec *field.Spec) field.Field { return field.NewNumeric(spec) },
 		"Binary":    func(spec *field.Spec) field.Field { return field.NewBinary(spec) },
 		"Bitmap":    func(spec *field.Spec) field.Field { return field.NewBitmap(spec) },

specs/builder_test.go

@@ -32,6 +32,15 @@ func TestBuilder(t *testing.T) {
 	require.Exactly(t, Spec87Hex.Name, hexSpec.Name)
 }
 
+func TestImportingJSONWithTrack2Spec(t *testing.T) {
+	track2Json, err := os.ReadFile("../examples/fields/track2.json")
+	require.NoError(t, err)
+
+	track2Spec, err := Builder.ImportJSON(track2Json)
+	require.NoError(t, err)
+	require.Exactly(t, Spec87Track2, track2Spec)
+}
+
 func TestExampleJSONSpec(t *testing.T) {
 	asciiJson, err := os.ReadFile("../examples/specs/spec87ascii.json")
 	require.NoError(t, err)

specs/track2.go

@@ -0,0 +1,21 @@
+package specs
+
+import (
+	"github.com/moov-io/iso8583"
+	"github.com/moov-io/iso8583/encoding"
+	"github.com/moov-io/iso8583/field"
+	"github.com/moov-io/iso8583/prefix"
+)
+
+// we keep it for compatibility reasons
+var Spec87Track2 *iso8583.MessageSpec = &iso8583.MessageSpec{
+	Name: "ISO 8583 v1987 Track2",
+	Fields: map[int]field.Field{
+		35: field.NewTrack2(&field.Spec{
+			Length:      37,
+			Description: "TRACK 2 DATA",
+			Enc:         encoding.ASCIIHexToBytes,
+			Pref:        prefix.Binary.L,
+		}),
+	},
+}