Add basic test for marshalling bank statement request

Also add marshalCheckRequest(), a helper function which prints the first
differences found between the two strings to aid in debugging test
failures.

banking_test.go

@@ -0,0 +1,73 @@
+package ofxgo_test
+
+import (
+	"github.com/aclindsa/ofxgo"
+	"testing"
+	"time"
+)
+
+func TestMarshalBankStatementRequest(t *testing.T) {
+	var expectedString string = `<?xml version="1.0" encoding="UTF-8" standalone="no"?>
+<?OFX OFXHEADER="200" VERSION="203" SECURITY="NONE" OLDFILEUID="NONE" NEWFILEUID="NONE"?>
+<OFX>
+	<SIGNONMSGSRQV1>
+		<SONRQ>
+			<DTCLIENT>20060115112300.000[-5:EST]</DTCLIENT>
+			<USERID>myusername</USERID>
+			<USERPASS>Pa$$word</USERPASS>
+			<LANGUAGE>ENG</LANGUAGE>
+			<FI>
+				<ORG>BNK</ORG>
+				<FID>1987</FID>
+			</FI>
+			<APPID>OFXGO</APPID>
+			<APPVER>0001</APPVER>
+		</SONRQ>
+	</SIGNONMSGSRQV1>
+	<BANKMSGSRQV1>
+		<STMTTRNRQ>
+			<TRNUID>123</TRNUID>
+			<STMTRQ>
+				<BANKACCTFROM>
+					<BANKID>318398732</BANKID>
+					<ACCTID>78346129</ACCTID>
+					<ACCTTYPE>CHECKING</ACCTTYPE>
+				</BANKACCTFROM>
+				<INCTRAN>
+					<INCLUDE>Y</INCLUDE>
+				</INCTRAN>
+			</STMTRQ>
+		</STMTTRNRQ>
+	</BANKMSGSRQV1>
+</OFX>`
+
+	var client = ofxgo.Client{
+		AppId:       "OFXGO",
+		AppVer:      "0001",
+		SpecVersion: "203",
+	}
+
+	var request ofxgo.Request
+	request.Signon.UserId = "myusername"
+	request.Signon.UserPass = "Pa$$word"
+	request.Signon.Org = "BNK"
+	request.Signon.Fid = "1987"
+
+	statementRequest := ofxgo.StatementRequest{
+		TrnUID: "123",
+		BankAcctFrom: ofxgo.BankAcct{
+			BankId:   "318398732",
+			AcctId:   "78346129",
+			AcctType: "CHECKING",
+		},
+		Include: true,
+	}
+	request.Banking = append(request.Banking, &statementRequest)
+
+	request.SetClientFields(&client)
+	// Overwrite the DtClient value set by SetClientFields to time.Now()
+	EST := time.FixedZone("EST", -5*60*60)
+	request.Signon.DtClient = ofxgo.Date(time.Date(2006, 1, 15, 11, 23, 0, 0, EST))
+
+	marshalCheckRequest(t, &request, expectedString)
+}