Failing test for #1500

Tests/GRDBTests/ValueObservationTests.swift

@@ -1268,5 +1268,56 @@ class ValueObservationTests: GRDBTestCase {
             onChange: { _ in
             })
     }
+
+    // Regression test for <https://github.com/groue/GRDB.swift/issues/1500>
+    func testIssue1500() throws {
+        struct Foo: Codable, FetchableRecord, PersistableRecord {
+            var id: String
+
+            static let bar = hasOne(Bar.self)
+            var bar: QueryInterfaceRequest<Bar> {
+                request(for: Self.bar)
+            }
+        }
+
+        struct Bar: Codable, FetchableRecord, PersistableRecord {
+            var fooId: String
+        }
+
+        var migrator = DatabaseMigrator()
+        migrator.registerMigration("v1") { db in
+            try db.create(table: "foo") { t in
+                t.column("id", .text).notNull().primaryKey()
+            }
+
+            try db.create(table: "bar") { t in
+                t.autoIncrementedPrimaryKey("id")
+                t.column("fooId", .text).notNull().unique().references("foo", onDelete: .cascade)
+            }
+        }
+
+        let pool = try makeDatabasePool()
+        try! pool.read { db in
+            if try migrator.hasBeenSuperseded(db) {
+                fatalError()
+            }
+        }
+
+        try! migrator.migrate(pool)
 
+        let observation = ValueObservation.trackingConstantRegion { db in
+            try Foo
+                .including(optional: Foo.bar)
+                .fetchOne(db)
+        }
+
+        let cancellable = observation.start(
+            in: pool,
+            scheduling: .immediate,
+            onError: { error in
+                XCTFail("Unexpected error \(error)")
+            },
+            onChange: { _ in
+            })
+    }
 }