Add translations for NodaTime LocalDate.{At,AtMidnight}

Closes #3576

Author: roji

src/EFCore.PG.NodaTime/Query/Internal/NpgsqlNodaTimeMethodCallTranslatorPlugin.cs

@@ -281,6 +281,27 @@ public NpgsqlNodaTimeMethodCallTranslator(
             return _sqlExpressionFactory.MakePostgresBinary(PgExpressionType.Distance, arguments[1], arguments[2]);
         }
 
+        if (method.DeclaringType == typeof(LocalDate))
+        {
+            return method.Name switch
+            {
+                nameof(LocalDate.At) => new SqlBinaryExpression(
+                    ExpressionType.Add,
+                    _sqlExpressionFactory.ApplyDefaultTypeMapping(instance!),
+                    _sqlExpressionFactory.ApplyDefaultTypeMapping(arguments[0]),
+                    typeof(LocalDateTime),
+                    _typeMappingSource.FindMapping(typeof(LocalDateTime))),
+
+                nameof(LocalDate.AtMidnight) => new SqlBinaryExpression(
+                    ExpressionType.Add,
+                    _sqlExpressionFactory.ApplyDefaultTypeMapping(instance!),
+                    new SqlConstantExpression(new LocalTime(0, 0, 0), _typeMappingSource.FindMapping(typeof(LocalTime))),
+                    typeof(LocalDateTime),
+                    _typeMappingSource.FindMapping(typeof(LocalDateTime))),
+
+                _ => null
+            };
+        }
         return null;
     }
 

test/EFCore.PG.FunctionalTests/Query/Translations/NodaTime/LocalDateTranslationsTest.cs

@@ -177,6 +177,38 @@ LIMIT 1
 """);
     }
 
+    [ConditionalTheory]
+    [MemberData(nameof(IsAsyncData))]
+    public async Task At(bool async)
+    {
+        await AssertQuery(
+            async,
+            ss => ss.Set<NodaTimeTypes>().Where(t => t.LocalDate.At(new LocalTime(12, 30, 0)) == new LocalDateTime(2018, 4, 20, 12, 30, 0)));
+
+AssertSql(
+"""
+SELECT n."Id", n."DateInterval", n."Duration", n."Instant", n."InstantRange", n."Interval", n."LocalDate", n."LocalDate2", n."LocalDateRange", n."LocalDateTime", n."LocalTime", n."Long", n."OffsetTime", n."Period", n."TimeZoneId", n."ZonedDateTime"
+FROM "NodaTimeTypes" AS n
+WHERE n."LocalDate" + TIME '12:30:00' = TIMESTAMP '2018-04-20T12:30:00'
+""");
+    }
+
+    [ConditionalTheory]
+    [MemberData(nameof(IsAsyncData))]
+    public async Task AtMidnight(bool async)
+    {
+        await AssertQuery(
+            async,
+            ss => ss.Set<NodaTimeTypes>().Where(t => t.LocalDate.AtMidnight() == new LocalDateTime(2018, 4, 20, 0, 0, 0)));
+
+AssertSql(
+"""
+SELECT n."Id", n."DateInterval", n."Duration", n."Instant", n."InstantRange", n."Interval", n."LocalDate", n."LocalDate2", n."LocalDateRange", n."LocalDateTime", n."LocalTime", n."Long", n."OffsetTime", n."Period", n."TimeZoneId", n."ZonedDateTime"
+FROM "NodaTimeTypes" AS n
+WHERE n."LocalDate" + TIME '00:00:00' = TIMESTAMP '2018-04-20T00:00:00'
+""");
+    }
+
     private NodaTimeContext CreateContext()
         => Fixture.CreateContext();