diff --git a/src/EFCore.SqlServer/Query/Internal/SqlServerStringMethodTranslator.cs b/src/EFCore.SqlServer/Query/Internal/SqlServerStringMethodTranslator.cs
index 01d3c238fe0..e1549339a51 100644
--- a/src/EFCore.SqlServer/Query/Internal/SqlServerStringMethodTranslator.cs
+++ b/src/EFCore.SqlServer/Query/Internal/SqlServerStringMethodTranslator.cs
@@ -443,7 +443,10 @@ private SqlExpression TranslateIndexOf(
 
         if (startIndex is not null)
         {
-            charIndexArguments.Add(_sqlExpressionFactory.Add(startIndex, _sqlExpressionFactory.Constant(1)));
+            charIndexArguments.Add(
+                startIndex is SqlConstantExpression { Value : int constantStartIndex }
+                    ? _sqlExpressionFactory.Constant(constantStartIndex + 1, typeof(int))
+                    : _sqlExpressionFactory.Add(startIndex, _sqlExpressionFactory.Constant(1)));
         }
 
         var argumentsPropagateNullability = Enumerable.Repeat(true, charIndexArguments.Count);
@@ -474,6 +477,15 @@ private SqlExpression TranslateIndexOf(
 
         charIndexExpression = _sqlExpressionFactory.Subtract(charIndexExpression, _sqlExpressionFactory.Constant(1));
 
+        // If the pattern is an empty string, we need to special case to always return 0 (since CHARINDEX return 0, which we'd subtract to
+        // -1). Handle separately for constant and non-constant patterns.
+        if (searchExpression is SqlConstantExpression { Value : string constantSearchPattern })
+        {
+            return constantSearchPattern == string.Empty
+                ? _sqlExpressionFactory.Constant(0, typeof(int))
+                : charIndexExpression;
+        }
+
         return _sqlExpressionFactory.Case(
             new[]
             {
diff --git a/test/EFCore.Cosmos.FunctionalTests/Query/NorthwindFunctionsQueryCosmosTest.cs b/test/EFCore.Cosmos.FunctionalTests/Query/NorthwindFunctionsQueryCosmosTest.cs
index 2a7a11ea566..e8fdcdbfa5f 100644
--- a/test/EFCore.Cosmos.FunctionalTests/Query/NorthwindFunctionsQueryCosmosTest.cs
+++ b/test/EFCore.Cosmos.FunctionalTests/Query/NorthwindFunctionsQueryCosmosTest.cs
@@ -812,9 +812,9 @@ FROM root c
 WHERE ((c[""Discriminator""] = ""Customer"") AND (INDEX_OF(c[""ContactName""], """") = 0))");
     }
 
-    public override async Task Indexof_with_one_arg(bool async)
+    public override async Task Indexof_with_one_constant_arg(bool async)
     {
-        await base.Indexof_with_one_arg(async);
+        await base.Indexof_with_one_constant_arg(async);
 
         AssertSql(
             @"SELECT c
@@ -822,9 +822,21 @@ FROM root c
 WHERE ((c[""Discriminator""] = ""Customer"") AND (INDEX_OF(c[""ContactName""], ""a"") = 1))");
     }
 
-    public override async Task Indexof_with_starting_position(bool async)
+    public override async Task Indexof_with_one_parameter_arg(bool async)
     {
-        await base.Indexof_with_starting_position(async);
+        await base.Indexof_with_one_parameter_arg(async);
+
+        AssertSql(
+            @"@__pattern_0='a'
+
+SELECT c
+FROM root c
+WHERE ((c[""Discriminator""] = ""Customer"") AND (INDEX_OF(c[""ContactName""], @__pattern_0) = 1))");
+    }
+
+    public override async Task Indexof_with_constant_starting_position(bool async)
+    {
+        await base.Indexof_with_constant_starting_position(async);
 
         AssertSql(
             @"SELECT c
@@ -832,6 +844,18 @@ FROM root c
 WHERE ((c[""Discriminator""] = ""Customer"") AND (INDEX_OF(c[""ContactName""], ""a"", 2) = 4))");
     }
 
+    public override async Task Indexof_with_parameter_starting_position(bool async)
+    {
+        await base.Indexof_with_parameter_starting_position(async);
+
+        AssertSql(
+            @"@__start_0='2'
+
+SELECT c
+FROM root c
+WHERE ((c[""Discriminator""] = ""Customer"") AND (INDEX_OF(c[""ContactName""], ""a"", @__start_0) = 4))");
+    }
+
     public override async Task Replace_with_emptystring(bool async)
     {
         await base.Replace_with_emptystring(async);
diff --git a/test/EFCore.Specification.Tests/Query/NorthwindFunctionsQueryTestBase.cs b/test/EFCore.Specification.Tests/Query/NorthwindFunctionsQueryTestBase.cs
index 7628ab02039..7af49885b8c 100644
--- a/test/EFCore.Specification.Tests/Query/NorthwindFunctionsQueryTestBase.cs
+++ b/test/EFCore.Specification.Tests/Query/NorthwindFunctionsQueryTestBase.cs
@@ -1413,7 +1413,7 @@ public virtual Task Indexof_with_emptystring(bool async)
 
     [ConditionalTheory]
     [MemberData(nameof(IsAsyncData))]
-    public virtual Task Indexof_with_one_arg(bool async)
+    public virtual Task Indexof_with_one_constant_arg(bool async)
         => AssertQuery(
             async,
             ss => ss.Set<Customer>().Where(c => c.ContactName.IndexOf("a") == 1),
@@ -1421,12 +1421,36 @@ public virtual Task Indexof_with_one_arg(bool async)
 
     [ConditionalTheory]
     [MemberData(nameof(IsAsyncData))]
-    public virtual Task Indexof_with_starting_position(bool async)
+    public virtual Task Indexof_with_one_parameter_arg(bool async)
+    {
+        var pattern = "a";
+
+        return AssertQuery(
+            async,
+            ss => ss.Set<Customer>().Where(c => c.ContactName.IndexOf(pattern) == 1),
+            entryCount: 32);
+    }
+
+    [ConditionalTheory]
+    [MemberData(nameof(IsAsyncData))]
+    public virtual Task Indexof_with_constant_starting_position(bool async)
         => AssertQuery(
             async,
             ss => ss.Set<Customer>().Where(c => c.ContactName.IndexOf("a", 2) == 4),
             entryCount: 15);
 
+    [ConditionalTheory]
+    [MemberData(nameof(IsAsyncData))]
+    public virtual Task Indexof_with_parameter_starting_position(bool async)
+    {
+        var start = 2;
+
+        return AssertQuery(
+            async,
+            ss => ss.Set<Customer>().Where(c => c.ContactName.IndexOf("a", start) == 4),
+            entryCount: 15);
+    }
+
     [ConditionalTheory]
     [MemberData(nameof(IsAsyncData))]
     public virtual Task Replace_with_emptystring(bool async)
diff --git a/test/EFCore.SqlServer.FunctionalTests/BuiltInDataTypesSqlServerTest.cs b/test/EFCore.SqlServer.FunctionalTests/BuiltInDataTypesSqlServerTest.cs
index 29bb00abd3c..e6e7827e39c 100644
--- a/test/EFCore.SqlServer.FunctionalTests/BuiltInDataTypesSqlServerTest.cs
+++ b/test/EFCore.SqlServer.FunctionalTests/BuiltInDataTypesSqlServerTest.cs
@@ -83,10 +83,7 @@ public void String_indexOf_over_varchar_max()
 
             Assert.Equal(-1, Assert.Single(results));
             AssertSql(
-                @"SELECT CASE
-    WHEN 'a' = '' THEN 0
-    ELSE CAST(CHARINDEX('a', [m].[StringAsVarcharMax]) AS int) - 1
-END
+                @"SELECT CAST(CHARINDEX('a', [m].[StringAsVarcharMax]) AS int) - 1
 FROM [MappedNullableDataTypes] AS [m]
 WHERE [m].[Int] = 81");
         }
diff --git a/test/EFCore.SqlServer.FunctionalTests/Query/NorthwindFunctionsQuerySqlServerTest.cs b/test/EFCore.SqlServer.FunctionalTests/Query/NorthwindFunctionsQuerySqlServerTest.cs
index 1c68d61d563..cba7f3a57ca 100644
--- a/test/EFCore.SqlServer.FunctionalTests/Query/NorthwindFunctionsQuerySqlServerTest.cs
+++ b/test/EFCore.SqlServer.FunctionalTests/Query/NorthwindFunctionsQuerySqlServerTest.cs
@@ -1575,30 +1575,51 @@ public override async Task Indexof_with_emptystring(bool async)
 FROM [Customers] AS [c]");
     }
 
-    public override async Task Indexof_with_one_arg(bool async)
+    public override async Task Indexof_with_one_constant_arg(bool async)
     {
-        await base.Indexof_with_one_arg(async);
+        await base.Indexof_with_one_constant_arg(async);
 
         AssertSql(
             @"SELECT [c].[CustomerID], [c].[Address], [c].[City], [c].[CompanyName], [c].[ContactName], [c].[ContactTitle], [c].[Country], [c].[Fax], [c].[Phone], [c].[PostalCode], [c].[Region]
 FROM [Customers] AS [c]
+WHERE (CAST(CHARINDEX(N'a', [c].[ContactName]) AS int) - 1) = 1");
+    }
+
+    public override async Task Indexof_with_one_parameter_arg(bool async)
+    {
+        await base.Indexof_with_one_parameter_arg(async);
+
+        AssertSql(
+            @"@__pattern_0='a' (Size = 4000)
+
+SELECT [c].[CustomerID], [c].[Address], [c].[City], [c].[CompanyName], [c].[ContactName], [c].[ContactTitle], [c].[Country], [c].[Fax], [c].[Phone], [c].[PostalCode], [c].[Region]
+FROM [Customers] AS [c]
 WHERE CASE
-    WHEN N'a' = N'' THEN 0
-    ELSE CAST(CHARINDEX(N'a', [c].[ContactName]) AS int) - 1
+    WHEN @__pattern_0 = N'' THEN 0
+    ELSE CAST(CHARINDEX(@__pattern_0, [c].[ContactName]) AS int) - 1
 END = 1");
     }
 
-    public override async Task Indexof_with_starting_position(bool async)
+    public override async Task Indexof_with_constant_starting_position(bool async)
     {
-        await base.Indexof_with_starting_position(async);
+        await base.Indexof_with_constant_starting_position(async);
 
         AssertSql(
             @"SELECT [c].[CustomerID], [c].[Address], [c].[City], [c].[CompanyName], [c].[ContactName], [c].[ContactTitle], [c].[Country], [c].[Fax], [c].[Phone], [c].[PostalCode], [c].[Region]
 FROM [Customers] AS [c]
-WHERE CASE
-    WHEN N'a' = N'' THEN 0
-    ELSE CAST(CHARINDEX(N'a', [c].[ContactName], 2 + 1) AS int) - 1
-END = 4");
+WHERE (CAST(CHARINDEX(N'a', [c].[ContactName], 3) AS int) - 1) = 4");
+    }
+
+    public override async Task Indexof_with_parameter_starting_position(bool async)
+    {
+        await base.Indexof_with_parameter_starting_position(async);
+
+        AssertSql(
+            @"@__start_0='2'
+
+SELECT [c].[CustomerID], [c].[Address], [c].[City], [c].[CompanyName], [c].[ContactName], [c].[ContactTitle], [c].[Country], [c].[Fax], [c].[Phone], [c].[PostalCode], [c].[Region]
+FROM [Customers] AS [c]
+WHERE (CAST(CHARINDEX(N'a', [c].[ContactName], @__start_0 + 1) AS int) - 1) = 4");
     }
 
     public override async Task Replace_with_emptystring(bool async)
@@ -1700,10 +1721,7 @@ public override async Task Substring_with_two_args_with_Index_of(bool async)
         await base.Substring_with_two_args_with_Index_of(async);
 
         AssertSql(
-            @"SELECT SUBSTRING([c].[ContactName], CASE
-    WHEN N'a' = N'' THEN 0
-    ELSE CAST(CHARINDEX(N'a', [c].[ContactName]) AS int) - 1
-END + 1, 3)
+            @"SELECT SUBSTRING([c].[ContactName], (CAST(CHARINDEX(N'a', [c].[ContactName]) AS int) - 1) + 1, 3)
 FROM [Customers] AS [c]
 WHERE [c].[CustomerID] = N'ALFKI'");
     }
diff --git a/test/EFCore.SqlServer.FunctionalTests/Query/NorthwindWhereQuerySqlServerTest.cs b/test/EFCore.SqlServer.FunctionalTests/Query/NorthwindWhereQuerySqlServerTest.cs
index c320a7d8dda..84b98380309 100644
--- a/test/EFCore.SqlServer.FunctionalTests/Query/NorthwindWhereQuerySqlServerTest.cs
+++ b/test/EFCore.SqlServer.FunctionalTests/Query/NorthwindWhereQuerySqlServerTest.cs
@@ -674,13 +674,7 @@ public override async Task Where_string_indexof(bool async)
         AssertSql(
             @"SELECT [c].[CustomerID], [c].[Address], [c].[City], [c].[CompanyName], [c].[ContactName], [c].[ContactTitle], [c].[Country], [c].[Fax], [c].[Phone], [c].[PostalCode], [c].[Region]
 FROM [Customers] AS [c]
-WHERE CASE
-    WHEN N'Sea' = N'' THEN 0
-    ELSE CAST(CHARINDEX(N'Sea', [c].[City]) AS int) - 1
-END <> -1 OR CASE
-    WHEN N'Sea' = N'' THEN 0
-    ELSE CAST(CHARINDEX(N'Sea', [c].[City]) AS int) - 1
-END IS NULL");
+WHERE (CAST(CHARINDEX(N'Sea', [c].[City]) AS int) - 1) <> -1 OR [c].[City] IS NULL");
     }
 
     public override async Task Where_string_replace(bool async)
diff --git a/test/EFCore.SqlServer.FunctionalTests/Query/NullSemanticsQuerySqlServerTest.cs b/test/EFCore.SqlServer.FunctionalTests/Query/NullSemanticsQuerySqlServerTest.cs
index 022e8d78ec8..717e349abd8 100644
--- a/test/EFCore.SqlServer.FunctionalTests/Query/NullSemanticsQuerySqlServerTest.cs
+++ b/test/EFCore.SqlServer.FunctionalTests/Query/NullSemanticsQuerySqlServerTest.cs
@@ -1248,36 +1248,15 @@ public override async Task Null_semantics_applied_when_comparing_function_with_n
         AssertSql(
             @"SELECT [e].[Id]
 FROM [Entities1] AS [e]
-WHERE CASE
-    WHEN N'oo' = N'' THEN 0
-    ELSE CAST(CHARINDEX(N'oo', [e].[NullableStringA]) AS int) - 1
-END = [e].[NullableIntA] OR (CASE
-    WHEN N'oo' = N'' THEN 0
-    ELSE CAST(CHARINDEX(N'oo', [e].[NullableStringA]) AS int) - 1
-END IS NULL AND [e].[NullableIntA] IS NULL)",
+WHERE (CAST(CHARINDEX(N'oo', [e].[NullableStringA]) AS int) - 1) = [e].[NullableIntA] OR ([e].[NullableStringA] IS NULL AND [e].[NullableIntA] IS NULL)",
             //
             @"SELECT [e].[Id]
 FROM [Entities1] AS [e]
-WHERE CASE
-    WHEN N'ar' = N'' THEN 0
-    ELSE CAST(CHARINDEX(N'ar', [e].[NullableStringA]) AS int) - 1
-END = [e].[NullableIntA] OR (CASE
-    WHEN N'ar' = N'' THEN 0
-    ELSE CAST(CHARINDEX(N'ar', [e].[NullableStringA]) AS int) - 1
-END IS NULL AND [e].[NullableIntA] IS NULL)",
+WHERE (CAST(CHARINDEX(N'ar', [e].[NullableStringA]) AS int) - 1) = [e].[NullableIntA] OR ([e].[NullableStringA] IS NULL AND [e].[NullableIntA] IS NULL)",
             //
             @"SELECT [e].[Id]
 FROM [Entities1] AS [e]
-WHERE (CASE
-    WHEN N'oo' = N'' THEN 0
-    ELSE CAST(CHARINDEX(N'oo', [e].[NullableStringA]) AS int) - 1
-END <> [e].[NullableIntB] OR CASE
-    WHEN N'oo' = N'' THEN 0
-    ELSE CAST(CHARINDEX(N'oo', [e].[NullableStringA]) AS int) - 1
-END IS NULL OR [e].[NullableIntB] IS NULL) AND (CASE
-    WHEN N'oo' = N'' THEN 0
-    ELSE CAST(CHARINDEX(N'oo', [e].[NullableStringA]) AS int) - 1
-END IS NOT NULL OR [e].[NullableIntB] IS NOT NULL)");
+WHERE ((CAST(CHARINDEX(N'oo', [e].[NullableStringA]) AS int) - 1) <> [e].[NullableIntB] OR [e].[NullableStringA] IS NULL OR [e].[NullableIntB] IS NULL) AND ([e].[NullableStringA] IS NOT NULL OR [e].[NullableIntB] IS NOT NULL)");
     }
 
     public override async Task Where_IndexOf_empty(bool async)
@@ -1293,10 +1272,7 @@ public override async Task Select_IndexOf(bool async)
         await base.Select_IndexOf(async);
 
         AssertSql(
-            @"SELECT CASE
-    WHEN N'oo' = N'' THEN 0
-    ELSE CAST(CHARINDEX(N'oo', [e].[NullableStringA]) AS int) - 1
-END
+            @"SELECT CAST(CHARINDEX(N'oo', [e].[NullableStringA]) AS int) - 1
 FROM [Entities1] AS [e]
 ORDER BY [e].[Id]");
     }
@@ -1308,63 +1284,15 @@ public override async Task Null_semantics_applied_when_comparing_two_functions_w
         AssertSql(
             @"SELECT [e].[Id]
 FROM [Entities1] AS [e]
-WHERE CASE
-    WHEN N'oo' = N'' THEN 0
-    ELSE CAST(CHARINDEX(N'oo', [e].[NullableStringA]) AS int) - 1
-END = CASE
-    WHEN N'ar' = N'' THEN 0
-    ELSE CAST(CHARINDEX(N'ar', [e].[NullableStringB]) AS int) - 1
-END OR (CASE
-    WHEN N'oo' = N'' THEN 0
-    ELSE CAST(CHARINDEX(N'oo', [e].[NullableStringA]) AS int) - 1
-END IS NULL AND CASE
-    WHEN N'ar' = N'' THEN 0
-    ELSE CAST(CHARINDEX(N'ar', [e].[NullableStringB]) AS int) - 1
-END IS NULL)",
+WHERE (CAST(CHARINDEX(N'oo', [e].[NullableStringA]) AS int) - 1) = (CAST(CHARINDEX(N'ar', [e].[NullableStringB]) AS int) - 1) OR ([e].[NullableStringA] IS NULL AND [e].[NullableStringB] IS NULL)",
             //
             @"SELECT [e].[Id]
 FROM [Entities1] AS [e]
-WHERE (CASE
-    WHEN N'oo' = N'' THEN 0
-    ELSE CAST(CHARINDEX(N'oo', [e].[NullableStringA]) AS int) - 1
-END <> CASE
-    WHEN N'ar' = N'' THEN 0
-    ELSE CAST(CHARINDEX(N'ar', [e].[NullableStringB]) AS int) - 1
-END OR CASE
-    WHEN N'oo' = N'' THEN 0
-    ELSE CAST(CHARINDEX(N'oo', [e].[NullableStringA]) AS int) - 1
-END IS NULL OR CASE
-    WHEN N'ar' = N'' THEN 0
-    ELSE CAST(CHARINDEX(N'ar', [e].[NullableStringB]) AS int) - 1
-END IS NULL) AND (CASE
-    WHEN N'oo' = N'' THEN 0
-    ELSE CAST(CHARINDEX(N'oo', [e].[NullableStringA]) AS int) - 1
-END IS NOT NULL OR CASE
-    WHEN N'ar' = N'' THEN 0
-    ELSE CAST(CHARINDEX(N'ar', [e].[NullableStringB]) AS int) - 1
-END IS NOT NULL)",
-            //
-            @"SELECT [e].[Id]
-FROM [Entities1] AS [e]
-WHERE (CASE
-    WHEN N'oo' = N'' THEN 0
-    ELSE CAST(CHARINDEX(N'oo', [e].[NullableStringA]) AS int) - 1
-END <> CASE
-    WHEN N'ar' = N'' THEN 0
-    ELSE CAST(CHARINDEX(N'ar', [e].[NullableStringA]) AS int) - 1
-END OR CASE
-    WHEN N'oo' = N'' THEN 0
-    ELSE CAST(CHARINDEX(N'oo', [e].[NullableStringA]) AS int) - 1
-END IS NULL OR CASE
-    WHEN N'ar' = N'' THEN 0
-    ELSE CAST(CHARINDEX(N'ar', [e].[NullableStringA]) AS int) - 1
-END IS NULL) AND (CASE
-    WHEN N'oo' = N'' THEN 0
-    ELSE CAST(CHARINDEX(N'oo', [e].[NullableStringA]) AS int) - 1
-END IS NOT NULL OR CASE
-    WHEN N'ar' = N'' THEN 0
-    ELSE CAST(CHARINDEX(N'ar', [e].[NullableStringA]) AS int) - 1
-END IS NOT NULL)");
+WHERE ((CAST(CHARINDEX(N'oo', [e].[NullableStringA]) AS int) - 1) <> (CAST(CHARINDEX(N'ar', [e].[NullableStringB]) AS int) - 1) OR [e].[NullableStringA] IS NULL OR [e].[NullableStringB] IS NULL) AND ([e].[NullableStringA] IS NOT NULL OR [e].[NullableStringB] IS NOT NULL)",
+            //
+            @"SELECT [e].[Id]
+FROM [Entities1] AS [e]
+WHERE ((CAST(CHARINDEX(N'oo', [e].[NullableStringA]) AS int) - 1) <> (CAST(CHARINDEX(N'ar', [e].[NullableStringA]) AS int) - 1) OR [e].[NullableStringA] IS NULL) AND [e].[NullableStringA] IS NOT NULL");
     }
 
     public override async Task Null_semantics_applied_when_comparing_two_functions_with_multiple_nullable_arguments(bool async)
diff --git a/test/EFCore.Sqlite.FunctionalTests/Query/NorthwindFunctionsQuerySqliteTest.cs b/test/EFCore.Sqlite.FunctionalTests/Query/NorthwindFunctionsQuerySqliteTest.cs
index a4534908533..8fd38b98d5c 100644
--- a/test/EFCore.Sqlite.FunctionalTests/Query/NorthwindFunctionsQuerySqliteTest.cs
+++ b/test/EFCore.Sqlite.FunctionalTests/Query/NorthwindFunctionsQuerySqliteTest.cs
@@ -332,9 +332,9 @@ public override async Task Indexof_with_emptystring(bool async)
 WHERE (instr(""c"".""ContactName"", '') - 1) = 0");
     }
 
-    public override async Task Indexof_with_one_arg(bool async)
+    public override async Task Indexof_with_one_constant_arg(bool async)
     {
-        await base.Indexof_with_one_arg(async);
+        await base.Indexof_with_one_constant_arg(async);
 
         AssertSql(
             @"SELECT ""c"".""CustomerID"", ""c"".""Address"", ""c"".""City"", ""c"".""CompanyName"", ""c"".""ContactName"", ""c"".""ContactTitle"", ""c"".""Country"", ""c"".""Fax"", ""c"".""Phone"", ""c"".""PostalCode"", ""c"".""Region""
@@ -342,8 +342,23 @@ public override async Task Indexof_with_one_arg(bool async)
 WHERE (instr(""c"".""ContactName"", 'a') - 1) = 1");
     }
 
-    public override Task Indexof_with_starting_position(bool async)
-        => AssertTranslationFailed(() => base.Indexof_with_starting_position(async));
+    public override async Task Indexof_with_one_parameter_arg(bool async)
+    {
+        await base.Indexof_with_one_parameter_arg(async);
+
+        AssertSql(
+            @"@__pattern_0='a' (Size = 1)
+
+SELECT ""c"".""CustomerID"", ""c"".""Address"", ""c"".""City"", ""c"".""CompanyName"", ""c"".""ContactName"", ""c"".""ContactTitle"", ""c"".""Country"", ""c"".""Fax"", ""c"".""Phone"", ""c"".""PostalCode"", ""c"".""Region""
+FROM ""Customers"" AS ""c""
+WHERE (instr(""c"".""ContactName"", @__pattern_0) - 1) = 1");
+    }
+
+    public override Task Indexof_with_constant_starting_position(bool async)
+        => AssertTranslationFailed(() => base.Indexof_with_constant_starting_position(async));
+
+    public override Task Indexof_with_parameter_starting_position(bool async)
+        => AssertTranslationFailed(() => base.Indexof_with_parameter_starting_position(async));
 
     public override async Task Replace_with_emptystring(bool async)
     {