Added 1 more test to integrity

tests/ArrowDbCore.Tests.Integrity/OverwriteForceClear.cs

@@ -0,0 +1,50 @@
+using Bogus;
+
+namespace ArrowDbCore.Tests.Integrity;
+
+public class OverwriteForceClear {
+    [Fact]
+    public async Task SerializeOverwritesExistingFile() {
+        const int itemCount = 1_000;
+
+        var faker = new Faker<Person>();
+        faker.UseSeed(1337);
+        faker.RuleFor(p => p.Name, (f, _) => f.Name.FullName());
+        faker.RuleFor(p => p.Age, (f, _) => f.Random.Int(1, 100));
+        faker.RuleFor(p => p.BirthDate, (f, _) => f.Date.Past(1, DateTime.Now.AddYears(-100)));
+        faker.RuleFor(p => p.IsMarried, (f, _) => f.Random.Bool());
+
+        var buffer = new char[256];
+
+        var path = Sharpify.Utils.Env.PathInBaseDirectory("overwrite-test.db");
+        try {
+            // load the db
+            var db = await ArrowDb.CreateFromFile(path);
+            // clear
+            db.Clear();
+            // add items
+            for (var j = 0; j < itemCount; j++) {
+                var person = faker.Generate();
+                var key = ArrowDb.GenerateTypedKey<Person>(person.Name, buffer);
+                db.Upsert(key, person, JContext.Default.Person);
+            }
+            // save
+            await db.SerializeAsync();
+            // now we have sample data to verify overwrite
+            var fileSize = new FileInfo(path).Length;
+            // now we overwrite
+            db.Clear();
+            await db.SerializeAsync();
+            // clear data and overwritten (file should next to empty - aside from headers)
+            var newFileSize = new FileInfo(path).Length;
+            // check if new is smaller
+            Assert.True(newFileSize < fileSize);
+        } finally {
+            if (File.Exists(path)) {
+                File.Delete(path);
+            }
+        }
+
+        // this test fails if an exception is thrown or the file is not overwritten
+    }
+}