Improve null handling

Author: asherber

PetaPoco.SqlKata.Tests/AutoGenerateTests.cs

@@ -180,6 +180,52 @@ public void Generate_T_SimpleClass_HasSelect()
             Compare(q, expected);
         }
 
+        [Fact]
+        public void ForType_NullQuery_Throws()
+        {
+            Query query = null;
+            Action act = () => query.ForType<MyClass>();
+            act.Should().Throw<ArgumentNullException>();
+        }
+
+        [Fact]
+        public void GenerateSelect_NullQuery_Throws()
+        {
+            Query query = null;
+            Action act = () => query.GenerateSelect<MyClass>();
+            act.Should().Throw<ArgumentNullException>();
+        }
+
+        [Fact]
+        public void ForType_NullMapper_Throws()
+        {
+            try
+            {
+                SqlKataExtensions.DefaultMapper = null;
+                Action act = () => new Query().ForType<MyClass>(null);
+                act.Should().Throw<ArgumentNullException>();
+            }
+            finally
+            {
+                SqlKataExtensions.DefaultMapper = new ConventionMapper();
+            }
+        }
+
+        [Fact]
+        public void GenerateSelect_NullMapper_Throws()
+        {
+            try
+            {
+                SqlKataExtensions.DefaultMapper = null;
+                Action act = () => new Query().GenerateSelect<MyClass>(null);
+                act.Should().Throw<ArgumentNullException>();
+            }
+            finally
+            {
+                SqlKataExtensions.DefaultMapper = new ConventionMapper();
+            }
+        }
+
         [Theory]
         [MemberData(nameof(Mappers))]
         public void Different_Mappers(IMapper mapper, string tableName, params string[] fieldNames)
@@ -200,24 +246,28 @@ public void Different_Mappers(IMapper mapper, string tableName, params string[]
         [MemberData(nameof(Mappers))]
         public void Different_Default_Mappers(IMapper mapper, string tableName, params string[] fieldNames)
         {
-            try
+            if (mapper != null)
             {
-                SqlKataExtensions.DefaultMapper = mapper;
-                var q = new Query().GenerateSelect<MyOtherClass>();
-                var expected = new Query(tableName).Select(fieldNames);
-                Compare(q, expected);
-            }
-            finally
-            {
-                SqlKataExtensions.DefaultMapper = new ConventionMapper();
-                PetaPoco.Mappers.RevokeAll();
+                try
+                {
+                    SqlKataExtensions.DefaultMapper = mapper;
+                    var q = new Query().GenerateSelect<MyOtherClass>();
+                    var expected = new Query(tableName).Select(fieldNames);
+                    Compare(q, expected);
+                }
+                finally
+                {
+                    SqlKataExtensions.DefaultMapper = new ConventionMapper();
+                    PetaPoco.Mappers.RevokeAll();
+                }
             }
         }
 
         public static IEnumerable<object[]> Mappers => new[]
         {
             new object[] { new UnderscoreMapper(), "my_other_class", "other_id", "other_name" },
             new object[] { new ConventionMapper(), "MyOtherClass", "OtherID", "OtherName" },
+            new object[] { null, "MyOtherClass", "OtherID", "OtherName" },
         };
     }
 

PetaPoco.SqlKata.Tests/ToSqlTests.cs

@@ -174,5 +174,12 @@ public void HasSelect_NoSelect_IsFalse()
             query.HasSelect().Should().BeFalse();
         }
 
+        [Fact]
+        public void NullQuery_ShouldThrow()
+        {
+            Query query = null;
+            Action act = () => query.ToSql();
+            act.Should().Throw<ArgumentNullException>();
+        }
     }
 }

PetaPoco.SqlKata/PetaPoco.SqlKata.cs

@@ -56,6 +56,8 @@ public static class SqlKataExtensions
         /// </summary>
         public static IMapper DefaultMapper { get; set; } = new ConventionMapper();
 
+
+
         /// <summary>
         /// Convert a <seealso cref="Query"/> object to a <seealso cref="Sql" /> object, 
         /// using a <seealso cref="SqlServerCompiler"/>.
@@ -72,6 +74,8 @@ public static class SqlKataExtensions
         /// <returns></returns>
         public static Sql ToSql(this Query query, CompilerType compilerType)
         {
+            query = query ?? throw new ArgumentNullException(nameof(query));
+
             var compiler = _compilers[compilerType].Value;
             var compiled = compiler.Compile(query);
             var ppSql = Helper.ReplaceAll(compiled.RawSql, "?", x => "@" + x);
@@ -113,6 +117,9 @@ public static Sql ToSql(this Query query, CompilerType compilerType)
         /// <returns></returns>
         public static Query ForType(this Query query, Type type, IMapper mapper)
         {
+            query = query ?? throw new ArgumentNullException(nameof(query));
+            mapper = mapper ?? DefaultMapper ?? throw new ArgumentNullException(nameof(mapper));
+
             var tableInfo = mapper.GetTableInfo(type);
             return query.From(tableInfo.TableName);
         }
@@ -187,6 +194,8 @@ public static Query GenerateSelect(this Query query, object poco, IMapper mapper
         /// <returns></returns>
         public static Query GenerateSelect(this Query query, Type type, IMapper mapper)
         {
+            query = query ?? throw new ArgumentNullException(nameof(query));
+
             if (!query.HasSelect())
             {
                 mapper = mapper ?? DefaultMapper ?? throw new ArgumentNullException(nameof(mapper));