ちょっと手間取ったのでメモ。

長々と書いてますが、ポイントは
・標準価格表で価格表エントリを登録した後でないと、他の価格表エントリは登録できない
・標準価格表は作れないので、Test.getStandardPricebookId()でIDを取得する。
の2点です。

コードで直接書く

まずは、普通にコードの中だけで作る方法。
価格表は標準価格表をそのまま使ってます。

CreateOpportunityTest.cls

@isTest
public class CreateOpportunityTest{

    @testSetup static void setUpTestData() {
        //insert Product2
        Product2 p2 = new Product2(
            Name = 'MyProduct'
            , IsActive = true
        );
        insert p2;

        //get standard pricebook Id
        Id pb2Id  = Test.getStandardPricebookId();

        //insert PriceBookEntry
        PriceBookEntry pbe = new PriceBookEntry(
            Pricebook2Id = pb2Id
            , Product2Id = p2.Id
            , UnitPrice = 100
            , IsActive = true
        );

        insert pbe;

        //insert Account
        Account a = new Account(
            Name = 'MyCompany'
        );

        insert a;

        //insert Opportunity
        Opportunity o = new Opportunity(
            Name = 'MyOpportunity'
            , AccountId = a.Id
            , StageName = 'Closed Won'
            , CloseDate = System.Today()
        );

        insert o;

        //insert OpportunityLineItem
        OpportunityLineItem oli = new OpportunityLineItem(
            OpportunityId = o.Id
            , PricebookEntryId = pbe.Id
            , Quantity = 5
            , TotalPrice = pbe.UnitPrice * 5
        );

        insert oli;
    }

　　//setupした内容をSELECTしてdebugで出すだけ
    @isTest static void testmethod1(){
        Product2 p2 = Database.query(cretaQueryAllFields(
            Schema.getGlobalDescribe().get('Product2').getDescribe()));

        system.debug('Product2:' + p2);

        PriceBookEntry pbe = Database.query(cretaQueryAllFields(
            Schema.getGlobalDescribe().get('PriceBookEntry').getDescribe()));

        system.debug('PriceBookEntry:' + pbe);

        Account a = Database.query(cretaQueryAllFields(
            Schema.getGlobalDescribe().get('Account').getDescribe()));

        system.debug('Account:' + a);

        Opportunity o = Database.query(cretaQueryAllFields(
            Schema.getGlobalDescribe().get('Opportunity').getDescribe()));

        system.debug('Opportunity:' + o);

        OpportunityLineItem oli = Database.query(cretaQueryAllFields(
            Schema.getGlobalDescribe().get('OpportunityLineItem').getDescribe()));

        system.debug('OpportunityLineItem:' + oli);
    }

　　//SELECT * 的な
    private static String cretaQueryAllFields(DescribeSObjectResult sObjResult) {
        String query = 'SELECT';
        Map<String, sObjectField> fields
          = sObjResult.fields.getMap();
        for(sObjectField f : fields.values()) {
            query += ' ' + f.getDescribe().getName() + ',';
        }
        query = query.removeEnd(',');
        query += ' FROM ' + sObjResult.getName();

        return query;
    }
}

CSVから取り込む

次にCSVを使う(Test.loadDataで取り込む)方法です。

標準価格表のIDを事前に把握しておけば、CSVから標準価格を登録することも出来そうなのですが、ベタにIDを埋め込むのはあんまりやりたくないので、標準価格の方はコードで適当な値を設定しておいて、カスタムの価格表をメインに使う方法でやってみます。

CreateOpportunityFromCSVTest.cls

@isTest
private class CreateOpportunityFromCSVTest {

    @testSetup static void setUpTestData() {
        //Insert Product2
        Test.loadData(Product2.sObjectType,'TestProducts');

        //Get standard pricebook Id
        Id pb2Id  = Test.getStandardPricebookId();

        //Insert Custom PriceBook
        Test.loadData(PriceBook2.sObjectType,'TestPriceBooks');

        //Insert Standard PriceBookEntry (中身は適当)
        List<Product2> products = [SELECT Id FROM Product2];
        List<PriceBookEntry> standardPriceBookEntry = new List<PriceBookEntry>();
        for(Product2 p : [SELECT Id FROM Product2]) {
            standardPriceBookEntry.add(new PriceBookEntry(
                Pricebook2Id = pb2Id
                , Product2Id = p.Id
                , UnitPrice = 0
                , IsActive = true
            ));
        }
        insert standardPriceBookEntry;

        //Insert Custom PriceBookEntry
        Test.loadData(PriceBookEntry.sObjectType,'TestPriceBookEntries');

        //Insert Account
        Test.loadData(Account.sObjectType,'TestAccounts');

        //Insert Opporunity
        Test.loadData(Opportunity.sObjectType,'TestOpportunities');

        //Insert OpportunityLineItem
        Test.loadData(OpportunityLineItem.sObjectType,'TestOpportunityLineitems');
    }

    @isTest static void testmethod1(){
        List<Product2> p2 = Database.query(cretaQueryAllFields(
            Schema.getGlobalDescribe().get('Product2').getDescribe()));

        system.debug('Product2:' + p2);


        List<PriceBook2> pb2 = Database.query(cretaQueryAllFields(
            Schema.getGlobalDescribe().get('PriceBook2').getDescribe()));

        system.debug('PriceBook2:' + pb2);


        List<PriceBookEntry> pbe = Database.query(cretaQueryAllFields(
            Schema.getGlobalDescribe().get('PriceBookEntry').getDescribe()));

        system.debug('PriceBookEntry:' + pbe);

        List<Account> a = Database.query(cretaQueryAllFields(
            Schema.getGlobalDescribe().get('Account').getDescribe()));

        system.debug('Account:' + a);

        List<Opportunity> o = Database.query(cretaQueryAllFields(
            Schema.getGlobalDescribe().get('Opportunity').getDescribe()));

        system.debug('Opportunity:' + o);

        List<OpportunityLineItem> oli = Database.query(cretaQueryAllFields(
            Schema.getGlobalDescribe().get('OpportunityLineItem').getDescribe()));

        system.debug('OpportunityLineItem:' + oli);
    }

    private static String cretaQueryAllFields(DescribeSObjectResult sObjResult) {
        String query = 'SELECT';
        Map<String, sObjectField> fields
          = sObjResult.fields.getMap();
        for(sObjectField f : fields.values()) {
            query += ' ' + f.getDescribe().getName() + ',';
        }
        query = query.removeEnd(',');
        query += ' FROM ' + sObjResult.getName();

        return query;
    }
}

各CSVファイルは以下のような感じ

TestAccounts.csv

ID	Name
ACC0001	MyCompany1
ACC0002	MyCompany2
ACC0003	MyCompany3
ACC0004	MyCompany4
ACC0005	MyCompany5

TestProducts.csv

ID	Name	IsActive
PRD0001	Myproduct1	TRUE
PRD0002	Myproduct2	TRUE
PRD0003	Myproduct3	TRUE
PRD0004	Myproduct4	TRUE
PRD0005	Myproduct5	TRUE

TestPriceBook.csv

ID	Name	IsActive
BRB0001	MyPriceBook1	TRUE

TestPriceBookEntries.csv

ID	Pricebook2Id	Product2Id	UnitPrice	IsActive	UseStandardPrice
PBE0001	BRB0001	PRD0001	50	TRUE	FALSE
PBE0002	BRB0001	PRD0002	100	TRUE	FALSE
PBE0003	BRB0001	PRD0003	150	TRUE	FALSE
PBE0004	BRB0001	PRD0004	200	TRUE	FALSE
PBE0005	BRB0001	PRD0005	250	TRUE	FALSE

TestOpportunities.csv

ID	Name	AccountId	StageName	CloseDate
OPP0001	Opportunity1	ACC0001	Closed Won	2017-01-01
OPP0002	Opportunity2	ACC0002	Closed Won	2017-02-01
OPP0003	Opportunity3	ACC0003	Closed Won	2017-03-01
OPP0004	Opportunity4	ACC0004	Closed Won	2017-04-01
OPP0005	Opportunity5	ACC0005	Closed Won	2017-05-01

TestOpportunitieLines.csv

OpportunityId	PricebookEntryId	Quantity	UnitPrice
OPP0001	PBE0001	5	50
OPP0001	PBE0002	4	100
OPP0001	PBE0003	3	150
OPP0001	PBE0004	2	200
OPP0001	PBE0005	1	250
OPP0002	PBE0001	5	50
OPP0002	PBE0002	4	100
OPP0002	PBE0003	3	150
OPP0002	PBE0004	2	200
OPP0002	PBE0005	1	250
OPP0003	PBE0001	5	50
OPP0003	PBE0002	4	100
OPP0003	PBE0003	3	150
OPP0003	PBE0004	2	200
OPP0003	PBE0005	1	250
OPP0004	PBE0001	5	50
OPP0004	PBE0002	4	100
OPP0004	PBE0003	3	150
OPP0004	PBE0004	2	200
OPP0004	PBE0005	1	250
OPP0005	PBE0001	5	50
OPP0005	PBE0002	4	100
OPP0005	PBE0003	3	150
OPP0005	PBE0004	2	200
OPP0005	PBE0005	1	250