CSHARP-5966 Add support of string.TrimStart and TrimEnd methods to SerializerFinder

src/MongoDB.Driver/Linq/Linq3Implementation/SerializerFinders/SerializerFinderVisitMethodCall.cs

@@ -157,7 +157,11 @@ void DeduceMethodCallSerializers()
                 case "ToHashedIndexKey": DeduceToHashedIndexKeySerializers(); break;
                 case "ToList": DeduceToListSerializers(); break;
                 case "ToString": DeduceToStringSerializers(); break;
-                case "Trim": DeduceTrimSerializers(); break;
+                case "Trim":
+                case "TrimStart":
+                case "TrimEnd":
+                    DeduceTrimSerializers();
+                    break;
                 case "Truncate": DeduceTruncateSerializers(); break;
                 case "Union": DeduceUnionSerializers(); break;
                 case "Week": DeduceWeekSerializers(); break;

tests/MongoDB.Driver.Tests/Linq/Integration/StringTrimTests.cs

@@ -0,0 +1,155 @@
+/* Copyright 2010-present MongoDB Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+using System.Collections.Generic;
+using System.Linq;
+using MongoDB.Driver.TestHelpers;
+using FluentAssertions;
+using Xunit;
+
+namespace MongoDB.Driver.Tests.Linq.Integration;
+
+public class StringTrimTests : LinqIntegrationTest<StringTrimTests.ClassFixture>
+{
+    public StringTrimTests(ClassFixture fixture)
+        : base(fixture)
+    {
+    }
+
+    [Fact]
+    public void Select_with_Trim_should_work()
+    {
+        var collection = Fixture.Collection;
+
+        var queryable = collection.AsQueryable()
+            .Select(x => x.Str.Trim());
+
+        var stages = Translate(collection, queryable);
+        AssertStages(stages, """{ $project : { _v : { $trim : { input : "$Str" } }, _id : 0 } }""");
+
+        var results = queryable.ToList();
+        results.Should().Equal("abcd", "abcd", "abcd", "abcd");
+    }
+
+    [Fact]
+    public void Select_with_Trim_with_chars_should_work()
+    {
+        var collection = Fixture.Collection;
+
+        var queryable = collection.AsQueryable()
+            .Select(x => x.Str.Trim(new[] { ' ', 'a' }));
+
+        var stages = Translate(collection, queryable);
+        AssertStages(stages, """{ $project : { _v : { $trim : { input : "$Str", chars : " a" } }, _id : 0 } }""");
+
+        var results = queryable.ToList();
+        results.Should().Equal("bcd", "bcd", "bcd", "bcd");
+    }
+
+    [Fact]
+    public void Select_with_Trim_with_empty_chars_should_work()
+    {
+        var collection = Fixture.Collection;
+
+        var queryable = collection.AsQueryable()
+            .Select(x => x.Str.Trim(new char[0]));
+
+        var stages = Translate(collection, queryable);
+        AssertStages(stages, """{ $project : { _v : { $trim : { input : "$Str" } }, _id : 0 } }""");
+
+        var results = queryable.ToList();
+        results.Should().Equal("abcd", "abcd", "abcd", "abcd");
+    }
+
+    [Fact]
+    public void Select_with_TrimStart_with_chars_should_work()
+    {
+        var collection = Fixture.Collection;
+
+        var queryable = collection.AsQueryable()
+            .Select(x => x.Str.TrimStart(new[] { ' ', 'a' }));
+
+        var stages = Translate(collection, queryable);
+        AssertStages(stages, """{ $project : { _v : { $ltrim : { input : "$Str", chars : " a" } }, _id : 0 } }""");
+
+        var results = queryable.ToList();
+        results.Should().Equal("bcd ", "bcd ", "bcd", "bcd");
+    }
+
+    [Fact]
+    public void Select_with_TrimStart_with_empty_chars_should_work()
+    {
+        var collection = Fixture.Collection;
+
+        var queryable = collection.AsQueryable()
+            .Select(x => x.Str.TrimStart(new char[0]));
+
+        var stages = Translate(collection, queryable);
+        AssertStages(stages, """{ $project : { _v : { $ltrim : { input : "$Str" } }, _id : 0 } }""");
+
+        var results = queryable.ToList();
+        results.Should().Equal("abcd ", "abcd ", "abcd", "abcd");
+    }
+
+    [Fact]
+    public void Select_with_TrimEnd_with_chars_should_work()
+    {
+        var collection = Fixture.Collection;
+
+        var queryable = collection.AsQueryable()
+            .Select(x => x.Str.TrimEnd(new[] { ' ', 'd' }));
+
+        var stages = Translate(collection, queryable);
+        AssertStages(stages, """{ $project : { _v : { $rtrim : { input : "$Str", chars : " d" } }, _id : 0 } }""");
+
+        var results = queryable.ToList();
+        results.Should().Equal(" abc", "abc", " abc", "abc");
+    }
+
+    [Fact]
+    public void Select_with_TrimEnd_with_empty_chars_should_work()
+    {
+        var collection = Fixture.Collection;
+
+        var queryable = collection.AsQueryable()
+            .Select(x => x.Str.TrimEnd(new char[0]));
+
+        var stages = Translate(collection, queryable);
+        AssertStages(stages, """{ $project : { _v : { $rtrim : { input : "$Str" } }, _id : 0 } }""");
+
+        var results = queryable.ToList();
+        results.Should().Equal(" abcd", "abcd", " abcd", "abcd");
+    }
+
+    // Add coverage for parameterless and single char overloads of Trim, TrimStart, and TrimEnd, see https://jira.mongodb.org/browse/CSHARP-5979
+    // e.g. Trim(' '), TrimStart(), TrimStart(' '), TrimEnd(), TrimEnd(' ')
+
+    public class C
+    {
+        public int Id { get; set; }
+        public string Str { get; set; }
+    }
+
+    public sealed class ClassFixture : MongoCollectionFixture<C>
+    {
+        protected override IEnumerable<C> InitialData =>
+        [
+            new C { Id = 1, Str = " abcd "},
+            new C { Id = 2, Str = "abcd "},
+            new C { Id = 3, Str = " abcd"},
+            new C { Id = 4, Str = "abcd"},
+        ];
+    }
+}

tests/MongoDB.Driver.Tests/Linq/Linq3Implementation/SerializerFinders/StringTests.cs

@@ -127,6 +127,8 @@ public void SerializerFinder_should_resolve_string_methods(LambdaExpression expr
         [TestHelpers.MakeLambda((MyModel model) => model.Name.ToUpperInvariant()), typeof(StringSerializer)],
         [TestHelpers.MakeLambda((MyModel model) => model.Name.Trim()), typeof(StringSerializer)],
         [TestHelpers.MakeLambda((MyModel model) => model.Name.Trim(new char[] { ' ' })), typeof(StringSerializer)],
+        [TestHelpers.MakeLambda((MyModel model) => model.Name.TrimStart(new char[] { ' ' })), typeof(StringSerializer)],
+        [TestHelpers.MakeLambda((MyModel model) => model.Name.TrimEnd(new char[] { ' ' })), typeof(StringSerializer)],
     ];
 
     [Theory]
@@ -153,6 +155,12 @@ public void SerializerFinder_should_set_unknowable_serializer_for_unsupported_st
         // StringComparison and CultureInfo overloads are not in ReplaceOverloads
         [TestHelpers.MakeLambda((MyModel model) => model.Name.Replace("old", "new", StringComparison.Ordinal))],
         [TestHelpers.MakeLambda((MyModel model) => model.Name.Replace("old", "new", false, CultureInfo.InvariantCulture))],
+        // Not supported yet, see https://jira.mongodb.org/browse/CSHARP-5979
+        [TestHelpers.MakeLambda((MyModel model) => model.Name.Trim(' '))],
+        [TestHelpers.MakeLambda((MyModel model) => model.Name.TrimStart(' '))],
+        [TestHelpers.MakeLambda((MyModel model) => model.Name.TrimEnd())],
+        [TestHelpers.MakeLambda((MyModel model) => model.Name.TrimStart())],
+        [TestHelpers.MakeLambda((MyModel model) => model.Name.TrimEnd())],
 #endif
     ];