diff --git a/test/pg_large_objects/ecto_query_test.exs b/test/pg_large_objects/ecto_query_test.exs
new file mode 100644
index 0000000..e270278
--- /dev/null
+++ b/test/pg_large_objects/ecto_query_test.exs
@@ -0,0 +1,29 @@
+defmodule PgLargeObjects.EctoQueryTest do
+  use PgLargeObjects.DataCase, async: true
+
+  import Ecto.Query
+  import PgLargeObjects.EctoQuery
+
+  describe "lo_create" do
+    test "creates a large object via Ecto query" do
+      query = from(x in fragment("SELECT 1 AS n"), select: lo_create())
+      assert [oid] = TestRepo.all(query)
+      assert is_integer(oid) and oid > 0
+    end
+  end
+
+  describe "lo_unlink" do
+    test "deletes a large object via Ecto query" do
+      oid = put_large_object!("test data")
+
+      values = [%{oid: oid}]
+      types = %{oid: :integer}
+
+      query = from(x in values(values, types), select: lo_unlink(x.oid))
+      TestRepo.all(query)
+
+      # Verify it's gone
+      assert {:error, :not_found} = PgLargeObjects.LargeObject.open(TestRepo, oid)
+    end
+  end
+end
diff --git a/test/pg_large_objects/large_object_test.exs b/test/pg_large_objects/large_object_test.exs
index 8cbae16..92de593 100644
--- a/test/pg_large_objects/large_object_test.exs
+++ b/test/pg_large_objects/large_object_test.exs
@@ -8,6 +8,22 @@ defmodule PgLargeObjects.LargeObjectTest do
       assert {:ok, %LargeObject{oid: oid}} = LargeObject.create(TestRepo)
       assert %{rows: [[^oid]]} = TestRepo.query!("SELECT oid FROM pg_largeobject_metadata")
     end
+
+    test "creates an object with custom bufsize" do
+      assert {:ok, %LargeObject{bufsize: 512}} = LargeObject.create(TestRepo, bufsize: 512)
+    end
+
+    test "creates an object opened for writing" do
+      {:ok, lob} = LargeObject.create(TestRepo, mode: :write)
+      assert :ok == LargeObject.write(lob, "test")
+    end
+
+    test "creates an object opened for read_write by default" do
+      {:ok, lob} = LargeObject.create(TestRepo)
+      assert :ok == LargeObject.write(lob, "test")
+      assert {:ok, 0} = LargeObject.seek(lob, 0)
+      assert {:ok, "test"} == LargeObject.read(lob, 10)
+    end
   end
 
   describe "open/3" do
@@ -20,6 +36,27 @@ defmodule PgLargeObjects.LargeObjectTest do
     test "fails given invalid object ID" do
       assert {:error, :not_found} == LargeObject.open(TestRepo, 12_345)
     end
+
+    test "opens for read_write mode allowing both read and write" do
+      oid = put_large_object!("ABCDEFG")
+
+      TestRepo.transaction(fn ->
+        {:ok, lob} = LargeObject.open(TestRepo, oid, mode: :read_write)
+        assert :ok == LargeObject.write(lob, "XYZ")
+        assert {:ok, 0} = LargeObject.seek(lob, 0)
+        assert {:ok, "XYZ"} == LargeObject.read(lob, 3)
+      end)
+    end
+
+    test "raises ArgumentError given invalid mode" do
+      oid = put_large_object!("test")
+
+      assert_raise ArgumentError, ~r/invalid mode/, fn ->
+        TestRepo.transaction(fn ->
+          LargeObject.open(TestRepo, oid, mode: :invalid)
+        end)
+      end
+    end
   end
 
   describe "remove/2" do
@@ -64,6 +101,16 @@ defmodule PgLargeObjects.LargeObjectTest do
         assert {:error, :not_found} == LargeObject.size(lob)
       end)
     end
+
+    test "preserves read position" do
+      with_object("ABCDEFGHIJ", fn lob ->
+        {:ok, "ABC"} = LargeObject.read(lob, 3)
+        assert {:ok, 3} = LargeObject.tell(lob)
+        assert {:ok, 10} = LargeObject.size(lob)
+        assert {:ok, 3} = LargeObject.tell(lob)
+        assert {:ok, "DEF"} = LargeObject.read(lob, 3)
+      end)
+    end
   end
 
   describe "write/2" do
@@ -310,7 +357,22 @@ defmodule PgLargeObjects.LargeObjectTest do
   end
 
   describe "Collectable implementation" do
-    test "raises when writing to a read-only object" do
+    test "Stream.into writes data to object" do
+      {:ok, oid} =
+        TestRepo.transaction(fn ->
+          {:ok, lob} = LargeObject.create(TestRepo, mode: :write)
+
+          ["Hello", ", ", "World!"]
+          |> Stream.into(lob)
+          |> Stream.run()
+
+          lob.oid
+        end)
+
+      assert get_large_object!(oid) == "Hello, World!"
+    end
+
+    test "raises on write error when streaming into read-only object" do
       oid = put_large_object!("hello")
 
       TestRepo.transaction(fn ->
@@ -344,7 +406,31 @@ defmodule PgLargeObjects.LargeObjectTest do
   end
 
   describe "Enumerable implementation" do
-    test "raises on read error" do
+    test "Enum.to_list returns chunks of data" do
+      with_object("ABCDEFGHIJ", [bufsize: 4], fn lob ->
+        assert Enum.to_list(lob) == ["ABCD", "EFGH", "IJ"]
+      end)
+    end
+
+    test "Enum.at returns the nth chunk" do
+      with_object("ABCDEFGHIJ", [bufsize: 4], fn lob ->
+        assert Enum.at(lob, 1) == "EFGH"
+      end)
+    end
+
+    test "Enum.count returns the number of chunks" do
+      with_object("ABCDEFGHIJ", [bufsize: 4], fn lob ->
+        assert Enum.count(lob) == 3
+      end)
+    end
+
+    test "Enum.slice returns a subset of chunks" do
+      with_object("ABCDEFGHIJKL", [bufsize: 4], fn lob ->
+        assert Enum.slice(lob, 1..2) == ["EFGH", "IJKL"]
+      end)
+    end
+
+    test "raises on read error when enumerating a closed object" do
       oid = put_large_object!("hello")
 
       TestRepo.transaction(fn ->
diff --git a/test/pg_large_objects/repo_test.exs b/test/pg_large_objects/repo_test.exs
index 436a0a4..12e6400 100644
--- a/test/pg_large_objects/repo_test.exs
+++ b/test/pg_large_objects/repo_test.exs
@@ -61,4 +61,40 @@ defmodule PgLargeObjects.RepoTest do
       assert {"", ^data} = StringIO.contents(pid)
     end
   end
+
+  describe "create_large_object/1" do
+    test "creates and opens a large object" do
+      TestRepo.transaction(fn ->
+        assert {:ok, %PgLargeObjects.LargeObject{}} = TestRepo.create_large_object()
+      end)
+    end
+  end
+
+  describe "open_large_object/2" do
+    test "opens an existing large object" do
+      oid = put_large_object!("test data")
+
+      TestRepo.transaction(fn ->
+        assert {:ok, %PgLargeObjects.LargeObject{oid: ^oid}} =
+                 TestRepo.open_large_object(oid)
+      end)
+    end
+
+    test "returns error for invalid oid" do
+      TestRepo.transaction(fn ->
+        assert {:error, :not_found} = TestRepo.open_large_object(12_345)
+      end)
+    end
+  end
+
+  describe "remove_large_object/1" do
+    test "removes an existing large object" do
+      oid = put_large_object!("test data")
+      assert :ok == TestRepo.remove_large_object(oid)
+    end
+
+    test "returns error for invalid oid" do
+      assert {:error, :not_found} = TestRepo.remove_large_object(12_345)
+    end
+  end
 end
diff --git a/test/pg_large_objects_test.exs b/test/pg_large_objects_test.exs
index 2de9951..8af1912 100644
--- a/test/pg_large_objects_test.exs
+++ b/test/pg_large_objects_test.exs
@@ -17,6 +17,31 @@ defmodule PgLargeObjectsTest do
       assert data == get_large_object!(oid)
     end
 
+    test "can import binary with custom bufsize" do
+      data = :crypto.strong_rand_bytes(256)
+
+      {:ok, oid} =
+        TestRepo.transaction(fn ->
+          {:ok, oid} = PgLargeObjects.import(TestRepo, data, bufsize: 64)
+          oid
+        end)
+
+      assert data == get_large_object!(oid)
+    end
+
+    test "can import large binary spanning multiple chunks" do
+      # 200KB with 64KB bufsize = 4 chunks (tests multi-chunk path)
+      data = :crypto.strong_rand_bytes(200_000)
+
+      {:ok, oid} =
+        TestRepo.transaction(fn ->
+          {:ok, oid} = PgLargeObjects.import(TestRepo, data, bufsize: 65_536)
+          oid
+        end)
+
+      assert data == get_large_object!(oid)
+    end
+
     test "can import from enumerable" do
       data = :crypto.strong_rand_bytes(Enum.random(0..1024))
 
@@ -67,5 +92,15 @@ defmodule PgLargeObjectsTest do
         assert {:error, :not_found} = PgLargeObjects.export(TestRepo, 12_345)
       end)
     end
+
+    test "handles invalid object IDs with collectable" do
+      {:ok, pid} = StringIO.open("", encoding: :latin1)
+      stream = IO.binstream(pid, 3)
+
+      TestRepo.transaction(fn ->
+        assert {:error, :not_found} =
+                 PgLargeObjects.export(TestRepo, 12_345, into: stream)
+      end)
+    end
   end
 end