diff --git a/wfassoc/src/highlevel/program.rs b/wfassoc/src/highlevel/program.rs
index 4fd0048..34485a4 100644
--- a/wfassoc/src/highlevel/program.rs
+++ b/wfassoc/src/highlevel/program.rs
@@ -55,6 +55,7 @@ pub enum ProgramError {
 // region: Program
 
 /// Program is a complete and immutable program representer
+#[derive(Debug)]
 pub struct Program {
     app_paths_key: lowlevel::AppPathsKey,
     applications_key: lowlevel::ApplicationsKey,
@@ -640,6 +641,7 @@ struct ProgramProgIdExtKey {
 /// Exposed struct representing this program provided method for opening specific file extension.
 ///
 /// The data including the extension name, diaplay name and icon.
+#[derive(Debug)]
 pub struct ProgramSelfExtStatus {
     ext: concept::Ext,
     name: String,
@@ -680,6 +682,7 @@ impl ProgramSelfExtStatus {
 /// Exposed struct representing the default associated program of specific file extension.
 ///
 /// The data including the diaplay name and icon.
+#[derive(Debug)]
 pub struct ProgramExtStatus {
     name: String,
     icon: concept::IconRc,
diff --git a/wfassoc/tests/highlevel.rs b/wfassoc/tests/highlevel.rs
index 28251e1..f983388 100644
--- a/wfassoc/tests/highlevel.rs
+++ b/wfassoc/tests/highlevel.rs
@@ -1,7 +1,169 @@
 use wfassoc::highlevel::*;
 mod common;
 
-#[test]
-fn test() {
-    common::check_sandbox();
+static IDENTIFIER: &str = "Passoc";
+static APP_PATH: &str = r"C:\Passoc\passoc.exe";
+static CLSID: &str = "{59031a47-3f72-44a7-89c5-5595fe6b30ee}";
+static EXT_BODY: &str = "pacfg";
+
+fn make_valid_schema() -> Schema {
+    let mut schema = Schema::new();
+    schema.set_identifier(IDENTIFIER);
+    schema.set_path(APP_PATH);
+    schema.set_clsid(CLSID);
+    schema.add_str("main_name", "Passoc Application").unwrap();
+    schema.add_str("ext_name", "Pacfg File").unwrap();
+    schema.add_icon("main_icon", r"notepad.exe,0").unwrap();
+    schema.add_icon("ext_icon", r"notepad.exe,0").unwrap();
+    schema.add_behavior("main_behavior", "notepad.exe %1").unwrap();
+    schema.add_behavior("ext_behavior", "notepad.exe %1").unwrap();
+    schema.set_name(Some("main_name"));
+    schema.set_icon(Some("main_icon"));
+    schema.set_behavior(Some("main_behavior"));
+    schema.add_ext(EXT_BODY, "ext_name", "ext_icon", "ext_behavior").unwrap();
+    schema
 }
+
+// region: Schema
+
+#[test]
+fn test_schema() {
+    common::check_sandbox();
+
+    // valid schema -> valid program
+    let schema = make_valid_schema();
+    let rv = schema.into_program();
+    assert!(rv.is_ok());
+
+    // missing identifier
+    let mut schema = Schema::new();
+    schema.set_path(APP_PATH);
+    let rv = schema.into_program();
+    assert!(rv.is_err());
+
+    // invalid path
+    let mut schema = Schema::new();
+    schema.set_identifier(IDENTIFIER);
+    schema.set_path(r"C:\");
+    let rv = schema.into_program();
+    assert!(rv.is_err());
+
+    // prepare a schema for following test
+    let mut schema = Schema::new();
+    schema.set_identifier(IDENTIFIER);
+    schema.set_path(APP_PATH);
+
+    // duplicate detection on add_str
+    let rv = schema.add_str("k", "v1");
+    assert!(rv.is_ok());
+    let rv = schema.add_str("k", "v2");
+    assert!(rv.is_err());
+
+    // duplicate detection on add_icon
+    let rv = schema.add_icon("k", "v1");
+    assert!(rv.is_ok());
+    let rv = schema.add_icon("k", "v2");
+    assert!(rv.is_err());
+
+    // duplicate detection on add_behavior
+    let rv = schema.add_behavior("k", "v1");
+    assert!(rv.is_ok());
+    let rv = schema.add_behavior("k", "v2");
+    assert!(rv.is_err());
+
+    // duplicate detection on add_ext
+    let rv = schema.add_ext(EXT_BODY, "k", "k", "k");
+    assert!(rv.is_ok());
+    let rv = schema.add_ext(EXT_BODY, "k", "k", "k");
+    assert!(rv.is_err());
+
+    // ext referencing non-existent map entry
+    schema.add_str("k2", "v").unwrap();
+    schema.add_icon("k2", "v").unwrap();
+    let rv = schema.add_ext("pacfg2", "nonexistent", "k2", "k2");
+    assert!(rv.is_ok());
+    let rv = schema.into_program();
+    assert!(rv.is_err());
+}
+
+// endregion
+
+// region: Program
+
+#[test]
+fn test_program() {
+    common::check_sandbox();
+
+    fn tester(scope: Scope, view: View) {
+        // build program
+        let schema = make_valid_schema();
+        let rv = schema.into_program();
+        assert!(rv.is_ok());
+        let mut program = rv.unwrap();
+
+        // cleanup before test
+        let rv = program.unregister(scope);
+        assert!(rv.is_ok());
+
+        // initially not registered
+        let rv = program.is_registered(scope);
+        assert!(rv.is_ok());
+        assert_eq!(rv.unwrap(), false);
+
+        // register
+        let rv = program.register(scope);
+        assert!(rv.is_ok());
+
+        // should be registered now
+        let rv = program.is_registered(scope);
+        assert!(rv.is_ok());
+        assert_eq!(rv.unwrap(), true);
+
+        // link_ext first so ext key exists before register
+        let rv = program.link_ext(scope, 0);
+        assert!(rv.is_ok());
+
+        // query_ext after link + register
+        let rv = program.query_ext(view, 0);
+        assert!(rv.is_ok());
+        assert!(rv.unwrap().is_some());
+
+        // unlink_ext
+        let rv = program.unlink_ext(scope, 0);
+        assert!(rv.is_ok());
+
+        // query_ext should return None
+        let rv = program.query_ext(view, 0);
+        assert!(rv.is_ok());
+        assert!(rv.unwrap().is_none());
+
+        // resolve_name, resolve_icon
+        let rv = program.resolve_name();
+        assert!(rv.is_ok());
+        let rv = program.resolve_icon();
+        assert!(rv.is_ok());
+
+        // exts_len, find_ext, resolve_ext
+        assert_eq!(program.exts_len(), 1);
+        assert_eq!(program.find_ext(EXT_BODY), Some(0));
+        let rv = program.resolve_ext(0);
+        assert!(rv.is_ok());
+
+        // bad index
+        let rv = program.resolve_ext(1);
+        assert!(rv.is_err());
+        let rv = program.link_ext(scope, 1);
+        assert!(rv.is_err());
+        let rv = program.query_ext(view, 1);
+        assert!(rv.is_err());
+
+        // cleanup
+        let rv = program.unregister(scope);
+        assert!(rv.is_ok());
+    }
+
+    tester(Scope::User, View::User);
+    tester(Scope::System, View::System);
+}
+
+// endregion
diff --git a/wfassoc/tests/lowlevel.rs b/wfassoc/tests/lowlevel.rs
index 51ce5b7..8b9322b 100644
--- a/wfassoc/tests/lowlevel.rs
+++ b/wfassoc/tests/lowlevel.rs
@@ -17,6 +17,161 @@ static VERB: LazyLock<ShellVerb> = LazyLock::new(|| {
     ShellVerb::new(verb, cmdline)
 });
 
+// region: AppPathsKey
+
+#[test]
+fn test_app_paths_key() {
+    common::check_sandbox();
+
+    static APP_PATH: &str = r"C:\Program Files\Passoc\passoc.exe";
+    static APP_DIR: &str = r"C:\Program Files\Passoc";
+
+    fn tester(scope: Scope) {
+        let mut key = AppPathsKey::new(APP_FILE.clone());
+
+        // delete and ensure
+        let rv = key.delete(scope);
+        assert!(rv.is_ok());
+        let rv = key.is_exist(scope);
+        assert!(rv.is_ok());
+        assert_eq!(rv.unwrap(), false);
+        let rv = key.ensure(scope);
+        assert!(rv.is_ok());
+        assert_eq!(rv.unwrap(), true);
+        let rv = key.is_exist(scope);
+        assert!(rv.is_ok());
+        assert_eq!(rv.unwrap(), true);
+        let rv = key.ensure(scope);
+        assert!(rv.is_ok());
+        assert_eq!(rv.unwrap(), false);
+
+        // get/set default
+        let rv = key.set_default(scope, APP_PATH);
+        assert!(rv.is_ok());
+        let rv = key.get_default(scope);
+        assert!(rv.is_ok());
+        assert_eq!(rv.unwrap(), APP_PATH);
+
+        // get/set path
+        let rv = key.set_path(scope, APP_DIR);
+        assert!(rv.is_ok());
+        let rv = key.get_path(scope);
+        assert!(rv.is_ok());
+        assert_eq!(rv.unwrap(), APP_DIR);
+
+        // clean up
+        let rv = key.delete(scope);
+        assert!(rv.is_ok());
+    }
+
+    tester(Scope::User);
+    tester(Scope::System);
+}
+
+// endregion
+
+// region: ApplicationsKey
+
+#[test]
+fn test_applications_key() {
+    common::check_sandbox();
+
+    static FRIENDLY_APP_NAME: LazyLock<StrResVariant> =
+        LazyLock::new(|| "Passoc Application".into());
+
+    fn tester(scope: Scope, view: View) {
+        let mut key = ApplicationsKey::new(APP_FILE.clone());
+
+        // delete and ensure
+        let rv = key.delete(scope);
+        assert!(rv.is_ok());
+        let rv = key.is_exist(view);
+        assert!(rv.is_ok());
+        assert_eq!(rv.unwrap(), false);
+        let rv = key.ensure(scope);
+        assert!(rv.is_ok());
+        assert_eq!(rv.unwrap(), true);
+        let rv = key.is_exist(view);
+        assert!(rv.is_ok());
+        assert_eq!(rv.unwrap(), true);
+        let rv = key.ensure(scope);
+        assert!(rv.is_ok());
+        assert_eq!(rv.unwrap(), false);
+
+        // get/set shell verb
+        let rv = key.set_shell_verb(scope, Some(&VERB));
+        assert!(rv.is_ok());
+        let rv = key.get_shell_verb(view);
+        assert!(rv.is_ok());
+        assert_eq!(rv.unwrap(), Some(VERB.clone()));
+        let rv = key.set_shell_verb(scope, None);
+        assert!(rv.is_ok());
+        let rv = key.get_shell_verb(view);
+        assert!(rv.is_ok());
+        assert_eq!(rv.unwrap(), None);
+
+        // get/set default icon
+        let rv = key.set_default_icon(scope, Some(&ICON));
+        assert!(rv.is_ok());
+        let rv = key.get_default_icon(view);
+        assert!(rv.is_ok());
+        assert_eq!(rv.unwrap(), Some(ICON.clone()));
+        let rv = key.set_default_icon(scope, None);
+        assert!(rv.is_ok());
+        let rv = key.get_default_icon(view);
+        assert!(rv.is_ok());
+        assert_eq!(rv.unwrap(), None);
+
+        // get/set friendly app name
+        let rv = key.set_friendly_app_name(scope, Some(&FRIENDLY_APP_NAME));
+        assert!(rv.is_ok());
+        let rv = key.get_friendly_app_name(view);
+        assert!(rv.is_ok());
+        assert_eq!(rv.unwrap(), Some(FRIENDLY_APP_NAME.clone()));
+        let rv = key.set_friendly_app_name(scope, None);
+        assert!(rv.is_ok());
+        let rv = key.get_friendly_app_name(view);
+        assert!(rv.is_ok());
+        assert_eq!(rv.unwrap(), None);
+
+        // get/set supported types
+        let rv = key.set_supported_types(scope, Some(&vec![EXT.deref()]));
+        assert!(rv.is_ok());
+        let rv = key.get_supported_types(view);
+        assert!(rv.is_ok());
+        assert_eq!(rv.unwrap(), Some(vec![EXT.clone()]));
+        let rv = key.set_supported_types(scope, None);
+        assert!(rv.is_ok());
+        let rv = key.get_supported_types(view);
+        assert!(rv.is_ok());
+        assert_eq!(rv.unwrap(), None);
+
+        // get/set no open with
+        let rv = key.get_no_open_with(view);
+        assert!(rv.is_ok());
+        assert_eq!(rv.unwrap(), false);
+        let rv = key.set_no_open_with(scope, true);
+        assert!(rv.is_ok());
+        let rv = key.get_no_open_with(view);
+        assert!(rv.is_ok());
+        assert_eq!(rv.unwrap(), true);
+        let rv = key.set_no_open_with(scope, false);
+        assert!(rv.is_ok());
+        let rv = key.get_no_open_with(view);
+        assert!(rv.is_ok());
+        assert_eq!(rv.unwrap(), false);
+
+        // clean up
+        let rv = key.delete(scope);
+        assert!(rv.is_ok());
+    }
+
+    tester(Scope::User, View::User);
+    tester(Scope::System, View::System);
+}
+
+// endregion
+
 // region: ExtKey
 
 #[test]
@@ -173,158 +328,3 @@ fn test_prog_id_key() {
 }
 
 // endregion
-
-// region: AppPathsKey
-
-#[test]
-fn test_app_paths_key() {
-    common::check_sandbox();
-
-    static APP_PATH: &str = r"C:\Program Files\Passoc\passoc.exe";
-    static APP_DIR: &str = r"C:\Program Files\Passoc";
-
-    fn tester(scope: Scope) {
-        let mut key = AppPathsKey::new(APP_FILE.clone());
-
-        // delete and ensure
-        let rv = key.delete(scope);
-        assert!(rv.is_ok());
-        let rv = key.is_exist(scope);
-        assert!(rv.is_ok());
-        assert_eq!(rv.unwrap(), false);
-        let rv = key.ensure(scope);
-        assert!(rv.is_ok());
-        assert_eq!(rv.unwrap(), true);
-        let rv = key.is_exist(scope);
-        assert!(rv.is_ok());
-        assert_eq!(rv.unwrap(), true);
-        let rv = key.ensure(scope);
-        assert!(rv.is_ok());
-        assert_eq!(rv.unwrap(), false);
-
-        // get/set default
-        let rv = key.set_default(scope, APP_PATH);
-        assert!(rv.is_ok());
-        let rv = key.get_default(scope);
-        assert!(rv.is_ok());
-        assert_eq!(rv.unwrap(), APP_PATH);
-
-        // get/set path
-        let rv = key.set_path(scope, APP_DIR);
-        assert!(rv.is_ok());
-        let rv = key.get_path(scope);
-        assert!(rv.is_ok());
-        assert_eq!(rv.unwrap(), APP_DIR);
-
-        // clean up
-        let rv = key.delete(scope);
-        assert!(rv.is_ok());
-    }
-
-    tester(Scope::User);
-    tester(Scope::System);
-}
-
-// endregion
-
-// region: ApplicationsKey
-
-#[test]
-fn test_applications_key() {
-    common::check_sandbox();
-
-    static FRIENDLY_APP_NAME: LazyLock<StrResVariant> =
-        LazyLock::new(|| "Passoc Application".into());
-
-    fn tester(scope: Scope, view: View) {
-        let mut key = ApplicationsKey::new(APP_FILE.clone());
-
-        // delete and ensure
-        let rv = key.delete(scope);
-        assert!(rv.is_ok());
-        let rv = key.is_exist(view);
-        assert!(rv.is_ok());
-        assert_eq!(rv.unwrap(), false);
-        let rv = key.ensure(scope);
-        assert!(rv.is_ok());
-        assert_eq!(rv.unwrap(), true);
-        let rv = key.is_exist(view);
-        assert!(rv.is_ok());
-        assert_eq!(rv.unwrap(), true);
-        let rv = key.ensure(scope);
-        assert!(rv.is_ok());
-        assert_eq!(rv.unwrap(), false);
-
-        // get/set shell verb
-        let rv = key.set_shell_verb(scope, Some(&VERB));
-        assert!(rv.is_ok());
-        let rv = key.get_shell_verb(view);
-        assert!(rv.is_ok());
-        assert_eq!(rv.unwrap(), Some(VERB.clone()));
-        let rv = key.set_shell_verb(scope, None);
-        assert!(rv.is_ok());
-        let rv = key.get_shell_verb(view);
-        assert!(rv.is_ok());
-        assert_eq!(rv.unwrap(), None);
-
-        // get/set default icon
-        let rv = key.set_default_icon(scope, Some(&ICON));
-        assert!(rv.is_ok());
-        let rv = key.get_default_icon(view);
-        assert!(rv.is_ok());
-        assert_eq!(rv.unwrap(), Some(ICON.clone()));
-        let rv = key.set_default_icon(scope, None);
-        assert!(rv.is_ok());
-        let rv = key.get_default_icon(view);
-        assert!(rv.is_ok());
-        assert_eq!(rv.unwrap(), None);
-
-        // get/set friendly app name
-        let rv = key.set_friendly_app_name(scope, Some(&FRIENDLY_APP_NAME));
-        assert!(rv.is_ok());
-        let rv = key.get_friendly_app_name(view);
-        assert!(rv.is_ok());
-        assert_eq!(rv.unwrap(), Some(FRIENDLY_APP_NAME.clone()));
-        let rv = key.set_friendly_app_name(scope, None);
-        assert!(rv.is_ok());
-        let rv = key.get_friendly_app_name(view);
-        assert!(rv.is_ok());
-        assert_eq!(rv.unwrap(), None);
-
-        // get/set supported types
-        let rv = key.set_supported_types(scope, Some(&vec![EXT.deref()]));
-        assert!(rv.is_ok());
-        let rv = key.get_supported_types(view);
-        assert!(rv.is_ok());
-        assert_eq!(rv.unwrap(), Some(vec![EXT.clone()]));
-        let rv = key.set_supported_types(scope, None);
-        assert!(rv.is_ok());
-        let rv = key.get_supported_types(view);
-        assert!(rv.is_ok());
-        assert_eq!(rv.unwrap(), None);
-
-        // get/set no open with
-        let rv = key.get_no_open_with(view);
-        assert!(rv.is_ok());
-        assert_eq!(rv.unwrap(), false);
-        let rv = key.set_no_open_with(scope, true);
-        assert!(rv.is_ok());
-        let rv = key.get_no_open_with(view);
-        assert!(rv.is_ok());
-        assert_eq!(rv.unwrap(), true);
-        let rv = key.set_no_open_with(scope, false);
-        assert!(rv.is_ok());
-        let rv = key.get_no_open_with(view);
-        assert!(rv.is_ok());
-        assert_eq!(rv.unwrap(), false);
-
-        // clean up
-        let rv = key.delete(scope);
-        assert!(rv.is_ok());
-    }
-
-    tester(Scope::User, View::User);
-    tester(Scope::System, View::System);
-}
-
-// endregion