diff --git a/inst/tinytest/test_providers.R b/inst/tinytest/test_providers.R
new file mode 100644
index 0000000..3767561
--- /dev/null
+++ b/inst/tinytest/test_providers.R
@@ -0,0 +1,24 @@
+# Test TTS provider configuration
+
+# tts_providers is a named list
+expect_true(is.list(tts_providers))
+expect_true(length(tts_providers) > 0)
+
+# Expected providers exist
+expect_true("OpenAI" %in% names(tts_providers))
+expect_true("ElevenLabs" %in% names(tts_providers))
+
+# Each provider has expected structure
+for (name in names(tts_providers)) {
+  p <- tts_providers[[name]]
+  expect_true(is.list(p), info = paste(name, "should be a list"))
+  expect_true("voices" %in% names(p) || is.null(p$voices),
+    info = paste(name, "should have voices field"))
+  expect_true("base_url" %in% names(p),
+    info = paste(name, "should have base_url"))
+}
+
+# OpenAI has static voice list
+expect_true(is.character(tts_providers[["OpenAI"]]$voices))
+expect_true("nova" %in% tts_providers[["OpenAI"]]$voices)
+expect_true("alloy" %in% tts_providers[["OpenAI"]]$voices)
diff --git a/inst/tinytest/test_speech_clone.R b/inst/tinytest/test_speech_clone.R
new file mode 100644
index 0000000..95f7e28
--- /dev/null
+++ b/inst/tinytest/test_speech_clone.R
@@ -0,0 +1,37 @@
+# Test speech_clone() input validation
+
+# input must be non-empty character
+expect_error(
+  speech_clone(NULL, voice_file = "x.wav"),
+  pattern = "non-empty character"
+)
+expect_error(
+  speech_clone("", voice_file = "x.wav"),
+  pattern = "non-empty character"
+)
+expect_error(
+  speech_clone(123, voice_file = "x.wav"),
+  pattern = "non-empty character"
+)
+
+# voice_file must be a character string
+expect_error(
+  speech_clone("hello", voice_file = NULL),
+  pattern = "character string"
+)
+expect_error(
+  speech_clone("hello", voice_file = 123),
+  pattern = "character string"
+)
+
+# voice_file must exist
+expect_error(
+  speech_clone("hello", voice_file = "nonexistent_xyz.wav"),
+  pattern = "not found"
+)
+
+# backend must be valid
+expect_error(
+  speech_clone("hello", voice_file = "x.wav", backend = "invalid"),
+  pattern = "arg"
+)
diff --git a/inst/tinytest/test_speech_design.R b/inst/tinytest/test_speech_design.R
new file mode 100644
index 0000000..ea54f9d
--- /dev/null
+++ b/inst/tinytest/test_speech_design.R
@@ -0,0 +1,21 @@
+# Test speech_design() input validation
+
+# input must be non-empty character
+expect_error(
+  speech_design(NULL, voice_description = "warm voice"),
+  pattern = "non-empty character"
+)
+expect_error(
+  speech_design("", voice_description = "warm voice"),
+  pattern = "non-empty character"
+)
+
+# voice_description must be non-empty character
+expect_error(
+  speech_design("hello", voice_description = NULL),
+  pattern = "non-empty character"
+)
+expect_error(
+  speech_design("hello", voice_description = ""),
+  pattern = "non-empty character"
+)