diff --git a/.github/workflows/more-ci.yml b/.github/workflows/more-ci.yml
index 25d8fb1..5e8549b 100644
--- a/.github/workflows/more-ci.yml
+++ b/.github/workflows/more-ci.yml
@@ -35,6 +35,9 @@ jobs:
           # We exclude the combination already tested in the 'ci' workflow.
           - os: ubuntu-latest
             ocaml-compiler: 5.2.x
+          # We exclude windows-4.14 - this fails when building core.
+          - os: windows-latest
+            ocaml-compiler: 4.14.x
 
     runs-on: ${{ matrix.os }}
 
@@ -52,16 +55,11 @@ jobs:
       #     janestreet-bleeding: https://github.com/janestreet/opam-repository.git
       #     janestreet-bleeding-external: https://github.com/janestreet/opam-repository.git#external-packages
 
+      # We build and run tests for a subset of packages. More tests are run in
+      # the development workflow and as part of the main CI job. These are the
+      # tests that are checked for every combination of os and ocaml-compiler.
       - name: Install dependencies
-        run: opam install ./provider.opam --deps-only --with-test
+        run: opam install ./provider.opam ./provider-tests.opam --deps-only --with-test
 
-      - name: Build
-        run: opam exec -- dune build @all -p provider
-
-      # For now, we only run tests for the `provider` package. Effectively, this
-      # runs nothing because the tests are in the `provider-test` package. We
-      # configured this in preparation for running the tests for specific
-      # packages only in the future, once we have a dedicated test suite that
-      # can run on every matrix combination configured here.
-      - name: Run tests
-        run: opam exec -- dune build @runtest -p provider
+      - name: Build & Run tests
+        run: opam exec -- dune build @all @runtest -p provider,provider-tests
diff --git a/doc/docs/reference/dune b/doc/docs/reference/dune
index 611baea..698f949 100644
--- a/doc/docs/reference/dune
+++ b/doc/docs/reference/dune
@@ -1,5 +1,5 @@
 (mdx
- (package provider-tests)
+ (package provider-dev)
  (deps
   (package provider)
   (glob_files *.txt))
diff --git a/doc/docs/tutorials/getting-started/dune b/doc/docs/tutorials/getting-started/dune
index 611baea..698f949 100644
--- a/doc/docs/tutorials/getting-started/dune
+++ b/doc/docs/tutorials/getting-started/dune
@@ -1,5 +1,5 @@
 (mdx
- (package provider-tests)
+ (package provider-dev)
  (deps
   (package provider)
   (glob_files *.txt))
diff --git a/doc/docs/tutorials/handler-explicit/dune b/doc/docs/tutorials/handler-explicit/dune
index 611baea..698f949 100644
--- a/doc/docs/tutorials/handler-explicit/dune
+++ b/doc/docs/tutorials/handler-explicit/dune
@@ -1,5 +1,5 @@
 (mdx
- (package provider-tests)
+ (package provider-dev)
  (deps
   (package provider)
   (glob_files *.txt))
diff --git a/dune-project b/dune-project
index cb39510..b4c8716 100644
--- a/dune-project
+++ b/dune-project
@@ -25,12 +25,64 @@
    (>= 4.14))
   (sexplib0
    (and
-    (>= v0.17)
+    (>= v0.16)
     (< v0.18)))))
 
 (package
  (name provider-tests)
  (synopsis "Tests for provider")
+ (depends
+  (ocaml
+   (>= 4.14))
+  (base
+   (and
+    (>= v0.16)
+    (< v0.18)))
+  (expect_test_helpers_core
+   (and
+    (>= v0.16)
+    (< v0.18)))
+  (ppx_compare
+   (and
+    (>= v0.16)
+    (< v0.18)))
+  (ppx_enumerate
+   (and
+    (>= v0.16)
+    (< v0.18)))
+  (ppx_expect
+   (and
+    (>= v0.16)
+    (< v0.18)))
+  (ppx_hash
+   (and
+    (>= v0.16)
+    (< v0.18)))
+  (ppx_here
+   (and
+    (>= v0.16)
+    (< v0.18)))
+  (ppx_let
+   (and
+    (>= v0.16)
+    (< v0.18)))
+  (ppx_sexp_conv
+   (and
+    (>= v0.16)
+    (< v0.18)))
+  (ppx_sexp_value
+   (and
+    (>= v0.16)
+    (< v0.18)))
+  (ppxlib
+   (>= 0.33))
+  (provider
+   (= :version))))
+
+(package
+ (name provider-dev)
+ (synopsis
+  "Package to regroup dev targets for the provider project, documentation, etc.")
  (depends
   (ocaml
    (>= 5.2))
@@ -101,6 +153,8 @@
    (>= 0.33))
   (provider
    (= :version))
+  (provider-tests
+   (= :version))
   (sherlodoc
    (and
     :with-doc
diff --git a/provider-dev.opam b/provider-dev.opam
new file mode 100644
index 0000000..007cf33
--- /dev/null
+++ b/provider-dev.opam
@@ -0,0 +1,51 @@
+# This file is generated by dune, edit dune-project instead
+opam-version: "2.0"
+synopsis:
+  "Package to regroup dev targets for the provider project, documentation, etc."
+maintainer: ["Mathieu Barbin <opensource@mbarbin.org>"]
+authors: ["Mathieu Barbin"]
+license: "ISC"
+homepage: "https://github.com/mbarbin/provider"
+doc: "https://mbarbin.github.io/provider/"
+bug-reports: "https://github.com/mbarbin/provider/issues"
+depends: [
+  "dune" {>= "3.16"}
+  "ocaml" {>= "5.2"}
+  "ocamlformat" {with-dev-setup & = "0.26.2"}
+  "base" {>= "v0.17" & < "v0.18"}
+  "bisect_ppx" {with-dev-setup & >= "2.8.3"}
+  "eio" {>= "1.0"}
+  "eio_main" {>= "1.0"}
+  "expect_test_helpers_core" {>= "v0.17" & < "v0.18"}
+  "higher_kinded" {>= "v0.17" & < "v0.18"}
+  "mdx" {>= "2.4"}
+  "ppx_compare" {>= "v0.17" & < "v0.18"}
+  "ppx_enumerate" {>= "v0.17" & < "v0.18"}
+  "ppx_expect" {>= "v0.17" & < "v0.18"}
+  "ppx_hash" {>= "v0.17" & < "v0.18"}
+  "ppx_here" {>= "v0.17" & < "v0.18"}
+  "ppx_js_style" {with-dev-setup & >= "v0.17" & < "v0.18"}
+  "ppx_let" {>= "v0.17" & < "v0.18"}
+  "ppx_sexp_conv" {>= "v0.17" & < "v0.18"}
+  "ppx_sexp_value" {>= "v0.17" & < "v0.18"}
+  "ppxlib" {>= "0.33"}
+  "provider" {= version}
+  "provider-tests" {= version}
+  "sherlodoc" {with-doc & >= "0.2"}
+  "odoc" {with-doc}
+]
+build: [
+  ["dune" "subst"] {dev}
+  [
+    "dune"
+    "build"
+    "-p"
+    name
+    "-j"
+    jobs
+    "@install"
+    "@runtest" {with-test}
+    "@doc" {with-doc}
+  ]
+]
+dev-repo: "git+https://github.com/mbarbin/provider.git"
diff --git a/provider-tests.opam b/provider-tests.opam
index 63ddc83..02f13d6 100644
--- a/provider-tests.opam
+++ b/provider-tests.opam
@@ -9,27 +9,19 @@ doc: "https://mbarbin.github.io/provider/"
 bug-reports: "https://github.com/mbarbin/provider/issues"
 depends: [
   "dune" {>= "3.16"}
-  "ocaml" {>= "5.2"}
-  "ocamlformat" {with-dev-setup & = "0.26.2"}
-  "base" {>= "v0.17" & < "v0.18"}
-  "bisect_ppx" {with-dev-setup & >= "2.8.3"}
-  "eio" {>= "1.0"}
-  "eio_main" {>= "1.0"}
-  "expect_test_helpers_core" {>= "v0.17" & < "v0.18"}
-  "higher_kinded" {>= "v0.17" & < "v0.18"}
-  "mdx" {>= "2.4"}
-  "ppx_compare" {>= "v0.17" & < "v0.18"}
-  "ppx_enumerate" {>= "v0.17" & < "v0.18"}
-  "ppx_expect" {>= "v0.17" & < "v0.18"}
-  "ppx_hash" {>= "v0.17" & < "v0.18"}
-  "ppx_here" {>= "v0.17" & < "v0.18"}
-  "ppx_js_style" {with-dev-setup & >= "v0.17" & < "v0.18"}
-  "ppx_let" {>= "v0.17" & < "v0.18"}
-  "ppx_sexp_conv" {>= "v0.17" & < "v0.18"}
-  "ppx_sexp_value" {>= "v0.17" & < "v0.18"}
+  "ocaml" {>= "4.14"}
+  "base" {>= "v0.16" & < "v0.18"}
+  "expect_test_helpers_core" {>= "v0.16" & < "v0.18"}
+  "ppx_compare" {>= "v0.16" & < "v0.18"}
+  "ppx_enumerate" {>= "v0.16" & < "v0.18"}
+  "ppx_expect" {>= "v0.16" & < "v0.18"}
+  "ppx_hash" {>= "v0.16" & < "v0.18"}
+  "ppx_here" {>= "v0.16" & < "v0.18"}
+  "ppx_let" {>= "v0.16" & < "v0.18"}
+  "ppx_sexp_conv" {>= "v0.16" & < "v0.18"}
+  "ppx_sexp_value" {>= "v0.16" & < "v0.18"}
   "ppxlib" {>= "0.33"}
   "provider" {= version}
-  "sherlodoc" {with-doc & >= "0.2"}
   "odoc" {with-doc}
 ]
 build: [
diff --git a/provider.opam b/provider.opam
index 75d2d81..5932e0c 100644
--- a/provider.opam
+++ b/provider.opam
@@ -10,7 +10,7 @@ bug-reports: "https://github.com/mbarbin/provider/issues"
 depends: [
   "dune" {>= "3.16"}
   "ocaml" {>= "4.14"}
-  "sexplib0" {>= "v0.17" & < "v0.18"}
+  "sexplib0" {>= "v0.16" & < "v0.18"}
   "odoc" {with-doc}
 ]
 build: [
diff --git a/test/dune b/test/dune
index 2316370..150fb43 100644
--- a/test/dune
+++ b/test/dune
@@ -14,10 +14,10 @@
   Expect_test_helpers_base)
  (libraries
   base
-  eio
-  eio_main
   expect_test_helpers_core.expect_test_helpers_base
   provider
+  test_interfaces
+  test_providers
   unix)
  (instrumentation
   (backend bisect_ppx))
@@ -34,5 +34,3 @@
    ppx_let
    ppx_sexp_conv
    ppx_sexp_value)))
-
-(include_subdirs qualified)
diff --git a/test/eio/dune b/test/eio/dune
new file mode 100644
index 0000000..28a4f02
--- /dev/null
+++ b/test/eio/dune
@@ -0,0 +1,39 @@
+(library
+ (name provider_test_eio)
+ (public_name provider-dev.provider_test_eio)
+ (inline_tests)
+ (flags
+  :standard
+  -w
+  +a-4-40-41-42-44-45-48-66
+  -warn-error
+  +a
+  -open
+  Base
+  -open
+  Expect_test_helpers_base)
+ (libraries
+  base
+  eio
+  eio_main
+  eio_test_providers
+  expect_test_helpers_core.expect_test_helpers_base
+  provider
+  test_interfaces
+  test_providers
+  unix)
+ (instrumentation
+  (backend bisect_ppx))
+ (lint
+  (pps ppx_js_style -check-doc-comments))
+ (preprocess
+  (pps
+   -unused-code-warnings=force
+   ppx_compare
+   ppx_enumerate
+   ppx_expect
+   ppx_hash
+   ppx_here
+   ppx_let
+   ppx_sexp_conv
+   ppx_sexp_value)))
diff --git a/test/test__reader.ml b/test/eio/test__reader.ml
similarity index 83%
rename from test/test__reader.ml
rename to test/eio/test__reader.ml
index 702f58d..55caab9 100644
--- a/test/test__reader.ml
+++ b/test/eio/test__reader.ml
@@ -25,7 +25,7 @@ let with_temp_dir ~env ~path ~f =
 let print_all_text_files t ~path =
   print_s
     [%sexp
-      (Interface.Directory_reader.find_files_with_extension t ~path ~ext:".txt"
+      (Test_interfaces.Directory_reader.find_files_with_extension t ~path ~ext:".txt"
        : string list)]
 ;;
 
@@ -33,10 +33,10 @@ let print_all_text_files t ~path =
    capabilities. *)
 let print_all_text_files_with_lines t ~path =
   List.iter
-    (Interface.Directory_reader.find_files_with_extension t ~path ~ext:".txt")
+    (Test_interfaces.Directory_reader.find_files_with_extension t ~path ~ext:".txt")
     ~f:(fun file ->
       let lines =
-        let contents = Interface.File_reader.load t ~path:(path ^ "/" ^ file) in
+        let contents = Test_interfaces.File_reader.load t ~path:(path ^ "/" ^ file) in
         List.sum (module Int) (String.split_lines contents) ~f:(Fn.const 1)
       in
       print_s [%sexp { file : string; lines : int }])
@@ -47,14 +47,14 @@ let print_all_text_files_with_lines t ~path =
    requiring it. *)
 let print_all_text_files_with_lines_if_available t ~path =
   List.iter
-    (Interface.Directory_reader.find_files_with_extension t ~path ~ext:".txt")
+    (Test_interfaces.Directory_reader.find_files_with_extension t ~path ~ext:".txt")
     ~f:(fun file ->
       let lines =
         let (Provider.T { t; handler }) = t in
         match
           Provider.Handler.lookup_opt
             handler
-            ~trait:Interface.File_reader.Provider_interface.File_reader
+            ~trait:Test_interfaces.File_reader.Provider_interface.File_reader
         with
         | None -> "not-available"
         | Some (module File_reader) ->
@@ -67,16 +67,18 @@ let print_all_text_files_with_lines_if_available t ~path =
 
 (* Now let's put it all together in a test. *)
 let%expect_test "test" =
-  let unix_reader = Providers.Unix_reader.make () in
+  let unix_reader = Test_providers.Unix_reader.make () in
   Eio_main.run
   @@ fun env ->
-  let eio_reader = Providers.Eio_reader.make ~env in
+  let eio_reader = Eio_test_providers.Eio_reader.make ~env in
   with_temp_dir ~env ~path:"test" ~f:(fun dir ->
     print_s
-      [%sexp (Interface.Directory_reader.readdir unix_reader ~path:dir : string list)];
+      [%sexp
+        (Test_interfaces.Directory_reader.readdir unix_reader ~path:dir : string list)];
     [%expect {| () |}];
     print_s
-      [%sexp (Interface.Directory_reader.readdir eio_reader ~path:dir : string list)];
+      [%sexp
+        (Test_interfaces.Directory_reader.readdir eio_reader ~path:dir : string list)];
     [%expect {| () |}];
     print_all_text_files unix_reader ~path:dir;
     [%expect {| () |}];
diff --git a/test/test__reader.mli b/test/eio/test__reader.mli
similarity index 100%
rename from test/test__reader.mli
rename to test/eio/test__reader.mli
diff --git a/test/eio/test_providers/dune b/test/eio/test_providers/dune
new file mode 100644
index 0000000..3073290
--- /dev/null
+++ b/test/eio/test_providers/dune
@@ -0,0 +1,36 @@
+(library
+ (name eio_test_providers)
+ (public_name provider-dev.eio_test_providers)
+ (inline_tests)
+ (flags
+  :standard
+  -w
+  +a-4-40-41-42-44-45-48-66
+  -warn-error
+  +a
+  -open
+  Base
+  -open
+  Expect_test_helpers_base)
+ (libraries
+  base
+  eio
+  expect_test_helpers_core.expect_test_helpers_base
+  test_interfaces
+  provider
+  unix)
+ (instrumentation
+  (backend bisect_ppx))
+ (lint
+  (pps ppx_js_style -check-doc-comments))
+ (preprocess
+  (pps
+   -unused-code-warnings=force
+   ppx_compare
+   ppx_enumerate
+   ppx_expect
+   ppx_hash
+   ppx_here
+   ppx_let
+   ppx_sexp_conv
+   ppx_sexp_value)))
diff --git a/test/providers/eio_reader.ml b/test/eio/test_providers/eio_reader.ml
similarity index 78%
rename from test/providers/eio_reader.ml
rename to test/eio/test_providers/eio_reader.ml
index 9bf28ac..869941c 100644
--- a/test/providers/eio_reader.ml
+++ b/test/eio/test_providers/eio_reader.ml
@@ -17,10 +17,10 @@ let make ~env : [ `Directory_reader | `File_reader ] Provider.t =
     ; handler =
         Provider.Handler.make
           [ Provider.Trait.implement
-              Interface.Directory_reader.Provider_interface.Directory_reader
+              Test_interfaces.Directory_reader.Provider_interface.Directory_reader
               ~impl:(module Impl)
           ; Provider.Trait.implement
-              Interface.File_reader.Provider_interface.File_reader
+              Test_interfaces.File_reader.Provider_interface.File_reader
               ~impl:(module Impl)
           ]
     }
diff --git a/test/providers/eio_reader.mli b/test/eio/test_providers/eio_reader.mli
similarity index 83%
rename from test/providers/eio_reader.mli
rename to test/eio/test_providers/eio_reader.mli
index 4c8052e..81688ca 100644
--- a/test/providers/eio_reader.mli
+++ b/test/eio/test_providers/eio_reader.mli
@@ -18,7 +18,7 @@ type t
     {!module:Interface.File_reader}. *)
 val make
   :  env:< fs : _ Eio.Path.t ; .. >
-  -> [ Interface.Directory_reader.tag | Interface.File_reader.tag ] Provider.t
+  -> [ Test_interfaces.Directory_reader.tag | Test_interfaces.File_reader.tag ] Provider.t
 
 (** In this specific example, we chose to expose the signature of the provider's
     implementation. This is not something that is usually required, since
@@ -28,6 +28,6 @@ val make
 module Impl : sig
   type nonrec t = t
 
-  include Interface.Directory_reader.Provider_interface.S with type t := t
-  include Interface.File_reader.Provider_interface.S with type t := t
+  include Test_interfaces.Directory_reader.Provider_interface.S with type t := t
+  include Test_interfaces.File_reader.Provider_interface.S with type t := t
 end
diff --git a/test/providers/num_printer.mli b/test/providers/num_printer.mli
deleted file mode 100644
index 395ef3d..0000000
--- a/test/providers/num_printer.mli
+++ /dev/null
@@ -1,15 +0,0 @@
-(** [Num_printer] is a provider for the {!module:Interface.Int_printer} and
-    {!module:Interface.Float_printer} interfaces.
-
-    The structure of this file is very similar to the [Eio_reader] module, thus
-    is not documented in details. Refer to {!Eio_reader} for more. *)
-
-(** In this case we decided to expose the type {!type:t} and {!val:handler}, to
-    demonstrate how to override a particular binding. See [test__override.ml]. *)
-type t = unit
-
-val handler
-  : (t, [ Interface.Int_printer.tag | Interface.Float_printer.tag ]) Provider.Handler.t
-
-(** If you simply wish to use this provider without overrides, use [make ()]. *)
-val make : t -> [ Interface.Int_printer.tag | Interface.Float_printer.tag ] Provider.t
diff --git a/test/test__cache.ml b/test/test__cache.ml
index c183ea2..b4cd71e 100644
--- a/test/test__cache.ml
+++ b/test/test__cache.ml
@@ -13,15 +13,15 @@ module Cache_state = struct
 end
 
 let%expect_test "override" =
-  let num_printer = Providers.Num_printer.make () in
+  let num_printer = Test_providers.Num_printer.make () in
   let cache_state_of_uid uid =
     if Provider.Trait.Uid.equal
          uid
-         (Interface.Int_printer.Provider_interface.Int_printer |> Provider.Trait.uid)
+         (Test_interfaces.Int_printer.Provider_interface.Int_printer |> Provider.Trait.uid)
     then Cache_state.Int_printer
     else if Provider.Trait.Uid.equal
               uid
-              (Interface.Float_printer.Provider_interface.Float_printer
+              (Test_interfaces.Float_printer.Provider_interface.Float_printer
                |> Provider.Trait.uid)
     then Cache_state.Float_printer
     else assert false [@coverage off]
@@ -45,8 +45,8 @@ let%expect_test "override" =
       ignore
         (Provider.Handler.lookup
            handler
-           ~trait:Interface.Int_printer.Provider_interface.Int_printer
-         : (module Interface.Int_printer.Provider_interface.S with type t = a)))
+           ~trait:Test_interfaces.Int_printer.Provider_interface.Int_printer
+         : (module Test_interfaces.Int_printer.Provider_interface.S with type t = a)))
       handler;
     require_equal
       [%here]
@@ -59,8 +59,8 @@ let%expect_test "override" =
       ignore
         (Provider.Handler.lookup
            handler
-           ~trait:Interface.Float_printer.Provider_interface.Float_printer
-         : (module Interface.Float_printer.Provider_interface.S with type t = a)))
+           ~trait:Test_interfaces.Float_printer.Provider_interface.Float_printer
+         : (module Test_interfaces.Float_printer.Provider_interface.S with type t = a)))
       handler;
     require_equal
       [%here]
@@ -74,7 +74,7 @@ let%expect_test "override" =
       (Option.is_some
          (Provider.Handler.lookup_opt
             handler
-            ~trait:Interface.Int_printer.Provider_interface.Int_printer));
+            ~trait:Test_interfaces.Int_printer.Provider_interface.Int_printer));
     require_equal
       [%here]
       (module Cache_state)
@@ -87,7 +87,7 @@ let%expect_test "override" =
       (Option.is_some
          (Provider.Handler.lookup_opt
             handler
-            ~trait:Interface.Float_printer.Provider_interface.Float_printer));
+            ~trait:Test_interfaces.Float_printer.Provider_interface.Float_printer));
     require_equal
       [%here]
       (module Cache_state)
@@ -100,7 +100,7 @@ let%expect_test "override" =
       [%here]
       (Provider.Handler.implements
          handler
-         ~trait:Interface.Int_printer.Provider_interface.Int_printer);
+         ~trait:Test_interfaces.Int_printer.Provider_interface.Int_printer);
     let post_cache_state = cache_state handler in
     require_equal [%here] (module Cache_state) pre_cache_state post_cache_state
   in
@@ -110,7 +110,7 @@ let%expect_test "override" =
       [%here]
       (Provider.Handler.implements
          handler
-         ~trait:Interface.Float_printer.Provider_interface.Float_printer);
+         ~trait:Test_interfaces.Float_printer.Provider_interface.Float_printer);
     let post_cache_state = cache_state handler in
     require_equal [%here] (module Cache_state) pre_cache_state post_cache_state
   in
diff --git a/test/test__introspection.ml b/test/test__introspection.ml
index e352c7f..5019eb4 100644
--- a/test/test__introspection.ml
+++ b/test/test__introspection.ml
@@ -17,9 +17,17 @@ let print_implements (Provider.T { t = _; handler }) =
     [%sexp
       { implements =
           { file_reader =
-              (implements Interface.File_reader.Provider_interface.File_reader : bool)
+              (implements Test_interfaces.File_reader.Provider_interface.File_reader
+               : bool)
           ; directory_reader =
-              (implements Interface.Directory_reader.Provider_interface.Directory_reader
+              (implements
+                 Test_interfaces.Directory_reader.Provider_interface.Directory_reader
+               : bool)
+          ; int_printer =
+              (implements Test_interfaces.Int_printer.Provider_interface.Int_printer
+               : bool)
+          ; float_printer =
+              (implements Test_interfaces.Float_printer.Provider_interface.Float_printer
                : bool)
           }
       }]
@@ -32,25 +40,32 @@ let%expect_test "introspection" =
     ((
       implements (
         (file_reader      false)
-        (directory_reader false)))) |}];
-  let unix_reader = Providers.Unix_reader.make () in
-  Eio_main.run
-  @@ fun env ->
-  let eio_reader = Providers.Eio_reader.make ~env in
-  print_implements eio_reader;
+        (directory_reader false)
+        (int_printer      false)
+        (float_printer    false))))
+    |}];
+  let int_printer = Test_providers.Int_printer.make () in
+  let num_printer = Test_providers.Num_printer.make () in
+  print_implements num_printer;
   [%expect
     {|
     ((
       implements (
-        (file_reader      true)
-        (directory_reader true)))) |}];
-  print_implements unix_reader;
+        (file_reader      false)
+        (directory_reader false)
+        (int_printer      true)
+        (float_printer    true))))
+    |}];
+  print_implements int_printer;
   [%expect
     {|
     ((
       implements (
         (file_reader      false)
-        (directory_reader true)))) |}];
+        (directory_reader false)
+        (int_printer      true)
+        (float_printer    false))))
+    |}];
   let id_mapping = Hashtbl.create (module Int) in
   let next_id = ref 0 in
   let sexp_of_id id =
@@ -66,21 +81,16 @@ let%expect_test "introspection" =
     Sexp.Atom (Int.to_string id)
   in
   Ref.set_temporarily Provider.Trait.Info.sexp_of_id sexp_of_id ~f:(fun () ->
-    print_implemented_traits unix_reader;
+    print_implemented_traits int_printer;
     [%expect
-      {|
-      ((
-        (id 0)
-        (name
-         Provider_test__Interface__Directory_reader.Provider_interface.Directory_reader))) |}];
-    print_implemented_traits eio_reader;
+      {| (((id 0) (name Test_interfaces.Int_printer.Provider_interface.Int_printer))) |}];
+    print_implemented_traits num_printer;
     [%expect
       {|
-      (((id 0)
-        (name
-         Provider_test__Interface__Directory_reader.Provider_interface.Directory_reader))
+      (((id 0) (name Test_interfaces.Int_printer.Provider_interface.Int_printer))
        ((id 1)
-        (name Provider_test__Interface__File_reader.Provider_interface.File_reader))) |}];
+        (name Test_interfaces.Float_printer.Provider_interface.Float_printer)))
+      |}];
     ());
   ()
 ;;
diff --git a/test/test__invalid_tags.ml b/test/test__invalid_tags.ml
index 7ed4a24..3ac6832 100644
--- a/test/test__invalid_tags.ml
+++ b/test/test__invalid_tags.ml
@@ -3,9 +3,9 @@
    runtime. *)
 
 let%expect_test "invalid tags" =
-  (* [Providers.Num_printer] was correctly built. *)
-  let print_42 printer = Interface.Int_printer.print printer 42 in
-  print_42 (Providers.Num_printer.make ());
+  (* [Test_providers.Num_printer] was correctly built. *)
+  let print_42 printer = Test_interfaces.Int_printer.print printer 42 in
+  print_42 (Test_providers.Num_printer.make ());
   [%expect {| 42 |}];
   (* Now let's build a provider with an empty interface, that claims however to
      implement the [Int_printer] interface. *)
@@ -21,7 +21,7 @@ let%expect_test "invalid tags" =
     ("Trait not implemented" ((
       trait_info (
         (id #id)
-        (name
-         Provider_test__Interface__Int_printer.Provider_interface.Int_printer))))) |}];
+        (name Test_interfaces.Int_printer.Provider_interface.Int_printer)))))
+    |}];
   ()
 ;;
diff --git a/test/test__make_handler.ml b/test/test__make_handler.ml
new file mode 100644
index 0000000..e12f2d5
--- /dev/null
+++ b/test/test__make_handler.ml
@@ -0,0 +1,79 @@
+(* This test is focused on the "make interface" functionality. We are testing
+   that different ways to create an interface -- using [make], [extend], [Trait.
+   implement], or the provider interface supplied maker -- all result in
+   equivalent interfaces. This ensures consistency across different methods of
+   interface creation. *)
+
+let%expect_test "int-printer" =
+  let printer = Test_providers.Int_printer.make () in
+  Test_interfaces.Int_printer.print printer 123_456_789;
+  [%expect {| 123456789 |}];
+  ()
+;;
+
+let%expect_test "make interface" =
+  let binding1 =
+    Provider.Trait.implement
+      Test_interfaces.Int_printer.Provider_interface.Int_printer
+      ~impl:(module Test_providers.Num_printer.Impl)
+  in
+  Test_interfaces.Int_printer.print
+    (Provider.T { t = (); handler = Provider.Handler.make [ binding1 ] })
+    1234;
+  [%expect {| 1234 |}];
+  let num1 =
+    Test_interfaces.Int_printer.Provider_interface.make
+      (module Test_providers.Num_printer.Impl)
+  in
+  Test_interfaces.Int_printer.print (Provider.T { t = (); handler = num1 }) 5678;
+  [%expect {| 5678 |}];
+  (match binding1, List.hd_exn (Provider.Handler.bindings num1) with
+   | T t, T t' ->
+     require [%here] (Provider.Trait.same t.trait t'.trait);
+     [%expect {||}];
+     ());
+  let binding2 =
+    Provider.Trait.implement
+      Test_interfaces.Float_printer.Provider_interface.Float_printer
+      ~impl:(module Test_providers.Num_printer.Impl)
+  in
+  (match binding1, binding2 with
+   | T t1, T t2 ->
+     print_s
+       [%sexp
+         { trait1 = (Provider.Trait.info t1.trait : Provider.Trait.Info.t)
+         ; trait2 = (Provider.Trait.info t2.trait : Provider.Trait.Info.t)
+         }];
+     [%expect
+       {|
+       ((trait1 (
+          (id #id) (name Test_interfaces.Int_printer.Provider_interface.Int_printer)))
+        (trait2 (
+          (id #id)
+          (name Test_interfaces.Float_printer.Provider_interface.Float_printer))))
+       |}];
+     require [%here] (not (Provider.Trait.same t1.trait t2.trait));
+     [%expect {||}];
+     ());
+  (match Provider.Handler.bindings num1 with
+   | [ c1 ] ->
+     require_equal
+       [%here]
+       (module Provider.Trait.Uid)
+       (Provider.Binding.uid c1)
+       (Provider.Binding.uid binding1);
+     [%expect {||}]
+   | _ -> assert false);
+  let empty = Provider.Handler.make [] in
+  require [%here] (Provider.Handler.is_empty empty);
+  require [%here] (List.is_empty (Provider.Handler.bindings empty));
+  let num2 = Provider.Handler.make [ binding2 ] in
+  require [%here] (not (Provider.Handler.is_empty num2));
+  require [%here] (not (Provider.Private.Handler.same_trait_uids empty num2));
+  [%expect {||}];
+  let num3 = Provider.Handler.make [ binding1; binding2 ] in
+  let num4 = Provider.Handler.extend num1 ~with_:(Provider.Handler.bindings num2) in
+  require [%here] (Provider.Private.Handler.same_trait_uids num3 num4);
+  [%expect {||}];
+  ()
+;;
diff --git a/test/test__make_interface.mli b/test/test__make_handler.mli
similarity index 100%
rename from test/test__make_interface.mli
rename to test/test__make_handler.mli
diff --git a/test/test__make_interface.ml b/test/test__make_interface.ml
deleted file mode 100644
index f8f887a..0000000
--- a/test/test__make_interface.ml
+++ /dev/null
@@ -1,66 +0,0 @@
-(* This test is focused on the "make interface" functionality. We are testing
-   that different ways to create an interface -- using [make], [extend], [Trait.
-   implement], or the provider interface supplied maker -- all result in
-   equivalent interfaces. This ensures consistency across different methods of
-   interface creation. *)
-
-let%expect_test "make interface" =
-  let trait1 =
-    Provider.Trait.implement
-      Interface.Directory_reader.Provider_interface.Directory_reader
-      ~impl:(module Providers.Eio_reader.Impl)
-  in
-  let eio1 =
-    Interface.Directory_reader.Provider_interface.make (module Providers.Eio_reader.Impl)
-  in
-  (match trait1, List.hd_exn (Provider.Handler.bindings eio1) with
-   | T t, T t' ->
-     require [%here] (Provider.Trait.same t.trait t'.trait);
-     [%expect {||}];
-     ());
-  let trait2 =
-    Provider.Trait.implement
-      Interface.File_reader.Provider_interface.File_reader
-      ~impl:(module Providers.Eio_reader.Impl)
-  in
-  (match trait1, trait2 with
-   | T t1, T t2 ->
-     print_s
-       [%sexp
-         { trait1 = (Provider.Trait.info t1.trait : Provider.Trait.Info.t)
-         ; trait2 = (Provider.Trait.info t2.trait : Provider.Trait.Info.t)
-         }];
-     [%expect
-       {|
-        ((trait1 (
-           (id #id)
-           (name
-            Provider_test__Interface__Directory_reader.Provider_interface.Directory_reader)))
-         (trait2 (
-           (id #id)
-           (name Provider_test__Interface__File_reader.Provider_interface.File_reader)))) |}];
-     require [%here] (not (Provider.Trait.same t1.trait t2.trait));
-     [%expect {||}];
-     ());
-  (match Provider.Handler.bindings eio1 with
-   | [ c1 ] ->
-     require_equal
-       [%here]
-       (module Provider.Trait.Uid)
-       (Provider.Binding.uid c1)
-       (Provider.Binding.uid trait1);
-     [%expect {||}]
-   | _ -> assert false);
-  let empty = Provider.Handler.make [] in
-  require [%here] (Provider.Handler.is_empty empty);
-  require [%here] (List.is_empty (Provider.Handler.bindings empty));
-  let eio2 = Provider.Handler.make [ trait2 ] in
-  require [%here] (not (Provider.Handler.is_empty eio2));
-  require [%here] (not (Provider.Private.Handler.same_trait_uids empty eio2));
-  [%expect {||}];
-  let eio3 = Provider.Handler.make [ trait1; trait2 ] in
-  let eio4 = Provider.Handler.extend eio1 ~with_:(Provider.Handler.bindings eio2) in
-  require [%here] (Provider.Private.Handler.same_trait_uids eio3 eio4);
-  [%expect {||}];
-  ()
-;;
diff --git a/test/test__override.ml b/test/test__override.ml
index 981cbdd..3e7c3e5 100644
--- a/test/test__override.ml
+++ b/test/test__override.ml
@@ -12,10 +12,10 @@ module Int_hum_printer = struct
       { t = ()
       ; handler =
           Provider.Handler.extend
-            Providers.Num_printer.handler
+            Test_providers.Num_printer.handler
             ~with_:
               [ Provider.Trait.implement
-                  Interface.Int_printer.Provider_interface.Int_printer
+                  Test_interfaces.Int_printer.Provider_interface.Int_printer
                   ~impl:(module Impl)
               ]
       }
@@ -31,18 +31,17 @@ let%expect_test "override" =
     print_s [%sexp (info : Sexp.t list)]
   in
   let test printer =
-    Interface.Int_printer.print printer 1234;
-    Interface.Float_printer.print printer 1234.5678
+    Test_interfaces.Int_printer.print printer 1234;
+    Test_interfaces.Float_printer.print printer 1234.5678
   in
-  let num_printer = Providers.Num_printer.make () in
+  let num_printer = Test_providers.Num_printer.make () in
   print_implemented_traits num_printer;
   [%expect
     {|
-      (((id #id)
-        (name
-         Provider_test__Interface__Float_printer.Provider_interface.Float_printer))
-       ((id #id)
-        (name Provider_test__Interface__Int_printer.Provider_interface.Int_printer))) |}];
+    (((id #id) (name Test_interfaces.Int_printer.Provider_interface.Int_printer))
+     ((id #id)
+      (name Test_interfaces.Float_printer.Provider_interface.Float_printer)))
+    |}];
   test num_printer;
   [%expect {|
       1234
@@ -51,11 +50,10 @@ let%expect_test "override" =
   print_implemented_traits hum_printer;
   [%expect
     {|
-      (((id #id)
-        (name
-         Provider_test__Interface__Float_printer.Provider_interface.Float_printer))
-       ((id #id)
-        (name Provider_test__Interface__Int_printer.Provider_interface.Int_printer))) |}];
+    (((id #id) (name Test_interfaces.Int_printer.Provider_interface.Int_printer))
+     ((id #id)
+      (name Test_interfaces.Float_printer.Provider_interface.Float_printer)))
+    |}];
   test hum_printer;
   (* Now there's an additional underscore separator in '1_234'. *)
   [%expect {|
diff --git a/test/interface/directory_reader.ml b/test/test_interfaces/directory_reader.ml
similarity index 100%
rename from test/interface/directory_reader.ml
rename to test/test_interfaces/directory_reader.ml
diff --git a/test/interface/directory_reader.mli b/test/test_interfaces/directory_reader.mli
similarity index 100%
rename from test/interface/directory_reader.mli
rename to test/test_interfaces/directory_reader.mli
diff --git a/test/test_interfaces/dune b/test/test_interfaces/dune
new file mode 100644
index 0000000..070bfc7
--- /dev/null
+++ b/test/test_interfaces/dune
@@ -0,0 +1,30 @@
+(library
+ (name test_interfaces)
+ (public_name provider-tests.test_interfaces)
+ (inline_tests)
+ (flags
+  :standard
+  -w
+  +a-4-40-41-42-44-45-48-66
+  -warn-error
+  +a
+  -open
+  Base
+  -open
+  Expect_test_helpers_base)
+ (libraries base expect_test_helpers_core.expect_test_helpers_base provider)
+ (instrumentation
+  (backend bisect_ppx))
+ (lint
+  (pps ppx_js_style -check-doc-comments))
+ (preprocess
+  (pps
+   -unused-code-warnings=force
+   ppx_compare
+   ppx_enumerate
+   ppx_expect
+   ppx_hash
+   ppx_here
+   ppx_let
+   ppx_sexp_conv
+   ppx_sexp_value)))
diff --git a/test/interface/file_reader.ml b/test/test_interfaces/file_reader.ml
similarity index 100%
rename from test/interface/file_reader.ml
rename to test/test_interfaces/file_reader.ml
diff --git a/test/interface/file_reader.mli b/test/test_interfaces/file_reader.mli
similarity index 100%
rename from test/interface/file_reader.mli
rename to test/test_interfaces/file_reader.mli
diff --git a/test/interface/float_printer.ml b/test/test_interfaces/float_printer.ml
similarity index 100%
rename from test/interface/float_printer.ml
rename to test/test_interfaces/float_printer.ml
diff --git a/test/interface/float_printer.mli b/test/test_interfaces/float_printer.mli
similarity index 100%
rename from test/interface/float_printer.mli
rename to test/test_interfaces/float_printer.mli
diff --git a/test/interface/int_printer.ml b/test/test_interfaces/int_printer.ml
similarity index 100%
rename from test/interface/int_printer.ml
rename to test/test_interfaces/int_printer.ml
diff --git a/test/interface/int_printer.mli b/test/test_interfaces/int_printer.mli
similarity index 100%
rename from test/interface/int_printer.mli
rename to test/test_interfaces/int_printer.mli
diff --git a/test/test_providers/dune b/test/test_providers/dune
new file mode 100644
index 0000000..182efd2
--- /dev/null
+++ b/test/test_providers/dune
@@ -0,0 +1,35 @@
+(library
+ (name test_providers)
+ (public_name provider-tests.test_providers)
+ (inline_tests)
+ (flags
+  :standard
+  -w
+  +a-4-40-41-42-44-45-48-66
+  -warn-error
+  +a
+  -open
+  Base
+  -open
+  Expect_test_helpers_base)
+ (libraries
+  base
+  expect_test_helpers_core.expect_test_helpers_base
+  test_interfaces
+  provider
+  unix)
+ (instrumentation
+  (backend bisect_ppx))
+ (lint
+  (pps ppx_js_style -check-doc-comments))
+ (preprocess
+  (pps
+   -unused-code-warnings=force
+   ppx_compare
+   ppx_enumerate
+   ppx_expect
+   ppx_hash
+   ppx_here
+   ppx_let
+   ppx_sexp_conv
+   ppx_sexp_value)))
diff --git a/test/test_providers/int_printer.ml b/test/test_providers/int_printer.ml
new file mode 100644
index 0000000..a805ea6
--- /dev/null
+++ b/test/test_providers/int_printer.ml
@@ -0,0 +1,17 @@
+module Impl = struct
+  type t = unit
+
+  let string_of_int () i = Int.to_string i
+end
+
+include Impl
+
+let handler : (unit, [ `Int_printer ]) Provider.Handler.t =
+  Provider.Handler.make
+    (List.concat
+       [ Test_interfaces.Int_printer.Provider_interface.make (module Impl)
+         |> Provider.Handler.bindings
+       ])
+;;
+
+let make () : [ `Int_printer ] Provider.t = Provider.T { t = (); handler }
diff --git a/test/test_providers/int_printer.mli b/test/test_providers/int_printer.mli
new file mode 100644
index 0000000..10b66c2
--- /dev/null
+++ b/test/test_providers/int_printer.mli
@@ -0,0 +1,11 @@
+(** [Int_printer] is a provider for {!module:Test_interfaces.Int_printer}.
+
+    The structure of this file is very similar to the [Eio_reader] module, thus
+    is not documented in details. Refer to {!Eio_reader} for more.
+
+    We use it as an alternate to [Num_printer], which is able to print both
+    integers and floats to demonstrate cases involving sub typing. *)
+
+type t = unit
+
+val make : t -> Test_interfaces.Int_printer.tag Provider.t
diff --git a/test/providers/num_printer.ml b/test/test_providers/num_printer.ml
similarity index 74%
rename from test/providers/num_printer.ml
rename to test/test_providers/num_printer.ml
index 9e447e9..1996392 100644
--- a/test/providers/num_printer.ml
+++ b/test/test_providers/num_printer.ml
@@ -10,9 +10,9 @@ include Impl
 let handler : (unit, [ `Int_printer | `Float_printer ]) Provider.Handler.t =
   Provider.Handler.make
     (List.concat
-       [ Interface.Int_printer.Provider_interface.make (module Impl)
+       [ Test_interfaces.Int_printer.Provider_interface.make (module Impl)
          |> Provider.Handler.bindings
-       ; Interface.Float_printer.Provider_interface.make (module Impl)
+       ; Test_interfaces.Float_printer.Provider_interface.make (module Impl)
          |> Provider.Handler.bindings
        ])
 ;;
diff --git a/test/test_providers/num_printer.mli b/test/test_providers/num_printer.mli
new file mode 100644
index 0000000..1b5df1c
--- /dev/null
+++ b/test/test_providers/num_printer.mli
@@ -0,0 +1,31 @@
+(** [Num_printer] is a provider for the {!module:Test_interfaces.Int_printer}
+    and {!module:Test_interfaces.Float_printer} interfaces.
+
+    The structure of this file is very similar to the [Eio_reader] module, thus
+    is not documented in details. Refer to {!Eio_reader} for more. *)
+
+(** In this case we decided to expose the type {!type:t} and {!val:handler}, to
+    demonstrate how to override a particular binding. See [test__override.ml]. *)
+type t = unit
+
+val handler
+  : ( t
+      , [ Test_interfaces.Int_printer.tag | Test_interfaces.Float_printer.tag ] )
+      Provider.Handler.t
+
+(** If you simply wish to use this provider without overrides, use [make ()]. *)
+val make
+  :  t
+  -> [ Test_interfaces.Int_printer.tag | Test_interfaces.Float_printer.tag ] Provider.t
+
+(** In this specific example, we chose to expose the signature of the provider's
+    implementation. This is not something that is usually required, since
+    {!make} already provides a way to build a provider. This is only done here
+    for the sake of the tests, as we show different ways an interface can be
+    built based on various parts of its implementation. *)
+module Impl : sig
+  type nonrec t = t
+
+  include Test_interfaces.Int_printer.Provider_interface.S with type t := t
+  include Test_interfaces.Float_printer.Provider_interface.S with type t := t
+end
diff --git a/test/providers/unix_reader.ml b/test/test_providers/unix_reader.ml
similarity index 55%
rename from test/providers/unix_reader.ml
rename to test/test_providers/unix_reader.ml
index a16da92..be9d21e 100644
--- a/test/providers/unix_reader.ml
+++ b/test/test_providers/unix_reader.ml
@@ -11,11 +11,6 @@ include Impl
 let make () : [ `Directory_reader ] Provider.t =
   Provider.T
     { t = ()
-    ; handler =
-        Provider.Handler.make
-          [ Provider.Trait.implement
-              Interface.Directory_reader.Provider_interface.Directory_reader
-              ~impl:(module Impl)
-          ]
+    ; handler = Test_interfaces.Directory_reader.Provider_interface.make (module Impl)
     }
 ;;
diff --git a/test/providers/unix_reader.mli b/test/test_providers/unix_reader.mli
similarity index 58%
rename from test/providers/unix_reader.mli
rename to test/test_providers/unix_reader.mli
index 8006b10..bbb693b 100644
--- a/test/providers/unix_reader.mli
+++ b/test/test_providers/unix_reader.mli
@@ -1,13 +1,13 @@
-(** [Unix_reader] is a provider for the {!module:Interface.Directory_reader}
-    interface based on [Unix].
+(** [Unix_reader] is a provider for {!module:Test_interfaces.Directory_reader}
+    based on [Unix].
 
     It is meant to demonstrate how to illustrate how multiple providers may be
     implemented the same interfaces. {!module:Eio_reader} is another provider
-    for the {!module:Interface.Directory_reader} interface.
+    for the {!module:Test_interfaces.Directory_reader} interface.
 
     The structure of this file is very similar to the [Eio_reader] module, thus
     is not documented in details. Refer to {!Eio_reader} for more. *)
 
 type t = unit
 
-val make : t -> Interface.Directory_reader.tag Provider.t
+val make : t -> Test_interfaces.Directory_reader.tag Provider.t