Second batch of unit tests

Making slight changes to RequestContext to make it easier to mock

test/Microsoft.SqlTools.ServiceLayer.Test/QueryExecution/SubsetTests.cs

@@ -1,11 +1,57 @@
 using System;
-using System.Collections.Generic;
-using System.Linq;
-using System.Threading.Tasks;
+using Microsoft.SqlTools.ServiceLayer.QueryExecution;
+using Microsoft.SqlTools.ServiceLayer.QueryExecution.Contracts;
+using Xunit;
 
 namespace Microsoft.SqlTools.ServiceLayer.Test.QueryExecution
 {
     public class SubsetTests
     {
+        [Theory]
+        [InlineData(2)]
+        [InlineData(20)]
+        public void SubsetValidTest(int rowCount)
+        {
+            // If I have an executed query
+            Query q = Common.GetBasicExecutedQuery();
+
+            // ... And I ask for a subset with valid arguments
+            ResultSetSubset subset = q.GetSubset(0, 0, rowCount);
+
+            // Then:
+            // I should get the requested number of rows
+            Assert.Equal(Math.Min(rowCount, Common.StandardTestData.Length), subset.RowCount);
+            Assert.Equal(Math.Min(rowCount, Common.StandardTestData.Length), subset.Rows.Length);
+        }
+
+        [Fact]
+        public void SubsetUnexecutedQueryTest()
+        {
+            // If I have a query that has *not* been executed
+            Query q = new Query("NO OP", Common.CreateTestConnectionInfo(null, false));
+
+            // ... And I ask for a subset with valid arguments
+            // Then:
+            // ... It should throw an exception
+            Assert.Throws<InvalidOperationException>(() => q.GetSubset(0, 0, 2));
+        }
+
+        [Theory]
+        [InlineData(-1, 0, 2)]  // Invalid result set, too low
+        [InlineData(2, 0, 2)]   // Invalid result set, too high
+        [InlineData(0, -1, 2)]  // Invalid start index, too low
+        [InlineData(0, 10, 2)]  // Invalid start index, too high
+        [InlineData(0, 0, -1)]  // Invalid row count, too low
+        [InlineData(0, 0, 0)]   // Invalid row count, zero
+        public void SubsetInvalidParamsTest(int resultSetIndex, int rowStartInex, int rowCount)
+        {
+            // If I have an executed query
+            Query q = Common.GetBasicExecutedQuery();
+
+            // ... And I ask for a subset with an invalid result set index
+            // Then: 
+            // ... It should throw an exception
+            Assert.Throws<ArgumentOutOfRangeException>(() => q.GetSubset(resultSetIndex, rowStartInex, rowCount));
+        }
     }
 }