New button template

README.md

@@ -63,11 +63,14 @@ point, use a composed template:
 
 ```bash
 anvil new weather_station --template weather --board uno
+anvil new clicker --template button --board uno
 ```
 
-The weather template builds on basic, adding a `WeatherApp` with a TMP36
+The **weather** template adds a `WeatherApp` with a TMP36 temperature sensor,
-temperature sensor driver, managed example tests demonstrating both mock and
+managed example tests, and student test starters. The **button** template adds
-simulator patterns, and student test starters. To see available templates:
+a `ButtonApp` with edge detection that prints "Button pressed!" to the serial
+monitor each time you press a button -- no repeated messages from holding it
+down. Both templates include mock and simulator patterns. To see all options:
 
 ```bash
 anvil new --list-templates
@@ -437,7 +440,7 @@ Upload these to a Gitea release. The script requires `build-essential`,
 cargo test
 ```
 
-615 tests (137 unit + 478 integration), ~4 seconds, zero warnings.
+642 tests (137 unit + 505 integration), ~4 seconds, zero warnings.
 
 ---
 

src/templates/mod.rs

@@ -10,6 +10,7 @@ use crate::version::ANVIL_VERSION;
 // Embedded template directories
 static BASIC_TEMPLATE: Dir = include_dir!("$CARGO_MANIFEST_DIR/templates/basic");
 static WEATHER_TEMPLATE: Dir = include_dir!("$CARGO_MANIFEST_DIR/templates/weather");
+static BUTTON_TEMPLATE: Dir = include_dir!("$CARGO_MANIFEST_DIR/templates/button");
 
 /// Context variables available in .tmpl files via {{VAR}} substitution.
 pub struct TemplateContext {
@@ -106,13 +107,17 @@ fn template_dir(name: &str) -> Option<&'static Dir<'static>> {
     match name {
         "basic" => Some(&BASIC_TEMPLATE),
         "weather" => Some(&WEATHER_TEMPLATE),
+        "button" => Some(&BUTTON_TEMPLATE),
         _ => None,
     }
 }
 
 // All composed templates (everything except "basic").
 fn composed_template_entries() -> Vec<(&'static str, &'static Dir<'static>)> {
-    vec![("weather", &WEATHER_TEMPLATE)]
+    vec![
+        ("weather", &WEATHER_TEMPLATE),
+        ("button", &BUTTON_TEMPLATE),
+    ]
 }
 
 // =========================================================================

templates/button/__name__/__name__.ino.tmpl

@@ -0,0 +1,35 @@
+/*
+ * {{PROJECT_NAME}}.ino -- Pushbutton input with edge detection
+ *
+ * Detects button presses (rising edge only) and prints to Serial:
+ *
+ *     Button pressed! (count: 1)
+ *     Button pressed! (count: 2)
+ *
+ * All logic lives in lib/app/{{PROJECT_NAME}}_app.h which depends
+ * on the HAL and Button interfaces, making it fully testable
+ * on the host without hardware.
+ *
+ * Wiring (active-low, no external resistor needed):
+ *   Pin 2    -> one leg of the button
+ *   GND      -> other leg of the button
+ *   (uses INPUT_PULLUP internally)
+ *
+ * Serial: 115200 baud
+ */
+
+#include <hal_arduino.h>
+#include <{{PROJECT_NAME}}_app.h>
+#include <button_digital.h>
+
+static ArduinoHal hw;
+static ButtonDigital btn(&hw, 2);  // pin 2, active-low (default)
+static ButtonApp app(&hw, &btn);
+
+void setup() {
+    app.begin();
+}
+
+void loop() {
+    app.update();
+}

templates/button/lib/app/__name___app.h.tmpl

@@ -0,0 +1,77 @@
+#ifndef APP_H
+#define APP_H
+
+#include <hal.h>
+#include "button.h"
+
+#include <stdio.h>
+
+/*
+ * ButtonApp -- Detects button presses and reports to Serial.
+ *
+ * Uses polling with edge detection: only triggers on the transition
+ * from released to pressed (rising edge). Holding the button does
+ * not generate repeated messages.
+ *
+ * Each press prints:
+ *     Button pressed! (count: 1)
+ *
+ * The button is injected through the Button interface, so this
+ * class works with real hardware, mocks, or simulations.
+ *
+ * Wiring (active-low, no external resistor needed):
+ *   Digital pin 2 -> one leg of the button
+ *   GND           -> other leg of the button
+ *   Set pin mode to INPUT_PULLUP in begin().
+ */
+class ButtonApp {
+public:
+    static constexpr uint8_t BUTTON_PIN = 2;
+
+    ButtonApp(Hal* hal, Button* button)
+        : hal_(hal)
+        , button_(button)
+        , was_pressed_(false)
+        , press_count_(0)
+    {}
+
+    // Call once from setup()
+    void begin() {
+        hal_->serialBegin(115200);
+        hal_->pinMode(BUTTON_PIN, INPUT_PULLUP);
+        hal_->serialPrintln("ButtonApp ready -- press the button!");
+        // Read initial state so we don't false-trigger on startup
+        was_pressed_ = button_->isPressed();
+    }
+
+    // Call repeatedly from loop()
+    void update() {
+        bool pressed_now = button_->isPressed();
+
+        // Rising edge: was released, now pressed
+        if (pressed_now && !was_pressed_) {
+            press_count_++;
+            onPress();
+        }
+
+        was_pressed_ = pressed_now;
+    }
+
+    // -- Accessors for testing ------------------------------------------------
+    int  pressCount()  const { return press_count_; }
+    bool wasPressed()  const { return was_pressed_; }
+
+private:
+    void onPress() {
+        char buf[40];
+        snprintf(buf, sizeof(buf), "Button pressed! (count: %d)", press_count_);
+        hal_->serialPrintln(buf);
+    }
+
+    Hal*    hal_;
+    Button* button_;
+    bool    was_pressed_;
+    int     press_count_;
+};
+
+#endif // APP_H

templates/button/template.toml

@@ -0,0 +1,25 @@
+[template]
+name = "button"
+base = "basic"
+description = "Pushbutton input with edge detection and serial output"
+
+[requires]
+libraries = ["button"]
+board_capabilities = ["digital"]
+
+# Default pin assignments per board.
+# Pin 2 supports interrupts on most boards, good default for buttons.
+[pins.default]
+button_signal = { pin = "2", mode = "input" }
+
+[pins.uno]
+button_signal = { pin = "2", mode = "input" }
+
+[pins.mega]
+button_signal = { pin = "2", mode = "input" }
+
+[pins.nano]
+button_signal = { pin = "2", mode = "input" }
+
+[pins.leonardo]
+button_signal = { pin = "2", mode = "input" }

templates/button/test/test_button_app.cpp.tmpl

@@ -0,0 +1,283 @@
+/*
+ * test_button_app.cpp -- Button application example tests.
+ *
+ * THIS FILE IS MANAGED BY ANVIL and will be updated by `anvil refresh`.
+ * Do not edit -- put your own tests in test_unit.cpp and test_system.cpp.
+ */
+
+#include <gtest/gtest.h>
+#include <gmock/gmock.h>
+
+#include "mock_arduino.h"
+#include "hal.h"
+#include "mock_hal.h"
+#include "sim_hal.h"
+#include "button_mock.h"
+#include "button_sim.h"
+#include "{{PROJECT_NAME}}_app.h"
+
+using ::testing::_;
+using ::testing::AnyNumber;
+using ::testing::Return;
+using ::testing::HasSubstr;
+
+// ============================================================================
+// Unit Tests -- verify ButtonApp behavior with mock button
+// ============================================================================
+
+class ButtonUnitTest : public ::testing::Test {
+protected:
+    void SetUp() override {
+        ON_CALL(mock_, millis()).WillByDefault(Return(0));
+        EXPECT_CALL(mock_, serialBegin(_)).Times(AnyNumber());
+        EXPECT_CALL(mock_, serialPrint(_)).Times(AnyNumber());
+        EXPECT_CALL(mock_, serialPrintln(_)).Times(AnyNumber());
+        EXPECT_CALL(mock_, millis()).Times(AnyNumber());
+        EXPECT_CALL(mock_, pinMode(_, _)).Times(AnyNumber());
+    }
+
+    ::testing::NiceMock<MockHal> mock_;
+    ButtonMock btn_;
+};
+
+TEST_F(ButtonUnitTest, BeginPrintsReadyMessage) {
+    ButtonApp app(&mock_, &btn_);
+
+    EXPECT_CALL(mock_, serialBegin(115200)).Times(1);
+    EXPECT_CALL(mock_, serialPrintln(HasSubstr("ButtonApp ready"))).Times(1);
+
+    app.begin();
+}
+
+TEST_F(ButtonUnitTest, BeginSetsPinMode) {
+    ButtonApp app(&mock_, &btn_);
+
+    EXPECT_CALL(mock_, pinMode(2, INPUT_PULLUP)).Times(1);
+
+    app.begin();
+}
+
+TEST_F(ButtonUnitTest, NoPressNoCount) {
+    ButtonApp app(&mock_, &btn_);
+    app.begin();
+
+    // Button not pressed, update should not increment count
+    btn_.setPressed(false);
+    app.update();
+    app.update();
+    app.update();
+
+    EXPECT_EQ(app.pressCount(), 0);
+}
+
+TEST_F(ButtonUnitTest, SinglePressIncrementsCount) {
+    ButtonApp app(&mock_, &btn_);
+    btn_.setPressed(false);
+    app.begin();
+
+    btn_.setPressed(true);
+    app.update();
+
+    EXPECT_EQ(app.pressCount(), 1);
+}
+
+TEST_F(ButtonUnitTest, HoldDoesNotRepeat) {
+    ButtonApp app(&mock_, &btn_);
+    btn_.setPressed(false);
+    app.begin();
+
+    btn_.setPressed(true);
+    app.update();  // rising edge -> count = 1
+    app.update();  // still pressed -> no increment
+    app.update();  // still pressed -> no increment
+
+    EXPECT_EQ(app.pressCount(), 1);
+}
+
+TEST_F(ButtonUnitTest, ReleaseAndPressAgain) {
+    ButtonApp app(&mock_, &btn_);
+    btn_.setPressed(false);
+    app.begin();
+
+    // First press
+    btn_.setPressed(true);
+    app.update();
+    EXPECT_EQ(app.pressCount(), 1);
+
+    // Release
+    btn_.setPressed(false);
+    app.update();
+
+    // Second press
+    btn_.setPressed(true);
+    app.update();
+    EXPECT_EQ(app.pressCount(), 2);
+}
+
+TEST_F(ButtonUnitTest, PrintsMessageOnPress) {
+    ButtonApp app(&mock_, &btn_);
+    btn_.setPressed(false);
+    app.begin();
+
+    EXPECT_CALL(mock_, serialPrintln(HasSubstr("Button pressed!"))).Times(1);
+
+    btn_.setPressed(true);
+    app.update();
+}
+
+TEST_F(ButtonUnitTest, PrintsCountInMessage) {
+    ButtonApp app(&mock_, &btn_);
+    btn_.setPressed(false);
+    app.begin();
+
+    EXPECT_CALL(mock_, serialPrintln(HasSubstr("count: 1"))).Times(1);
+
+    btn_.setPressed(true);
+    app.update();
+}
+
+TEST_F(ButtonUnitTest, DoesNotPrintOnRelease) {
+    ButtonApp app(&mock_, &btn_);
+    btn_.setPressed(false);
+    app.begin();
+
+    btn_.setPressed(true);
+    app.update();
+
+    // Release should not trigger another print
+    EXPECT_CALL(mock_, serialPrintln(HasSubstr("Button pressed!"))).Times(0);
+
+    btn_.setPressed(false);
+    app.update();
+}
+
+TEST_F(ButtonUnitTest, TenPresses) {
+    ButtonApp app(&mock_, &btn_);
+    btn_.setPressed(false);
+    app.begin();
+
+    for (int i = 0; i < 10; ++i) {
+        btn_.setPressed(true);
+        app.update();
+        btn_.setPressed(false);
+        app.update();
+    }
+
+    EXPECT_EQ(app.pressCount(), 10);
+}
+
+TEST_F(ButtonUnitTest, StartupWithButtonAlreadyPressed) {
+    // If the button is held during startup, begin() reads it as pressed.
+    // The first update() should NOT trigger a press (no rising edge).
+    btn_.setPressed(true);
+
+    ButtonApp app(&mock_, &btn_);
+    app.begin();
+
+    app.update();  // still pressed, no edge
+    EXPECT_EQ(app.pressCount(), 0);
+
+    // Release and press again -- THIS should trigger
+    btn_.setPressed(false);
+    app.update();
+    btn_.setPressed(true);
+    app.update();
+    EXPECT_EQ(app.pressCount(), 1);
+}
+
+// ============================================================================
+// System Tests -- exercise ButtonApp with simulated button and hardware
+// ============================================================================
+
+class ButtonSystemTest : public ::testing::Test {
+protected:
+    void SetUp() override {
+        mock_arduino_reset();
+        sim_.setMillis(0);
+    }
+
+    SimHal sim_;
+    ButtonSim btn_{0};  // no bounce for predictable tests
+};
+
+TEST_F(ButtonSystemTest, StartsAndPrintsToSerial) {
+    ButtonApp app(&sim_, &btn_);
+    app.begin();
+
+    std::string output = sim_.serialOutput();
+    EXPECT_NE(output.find("ButtonApp ready"), std::string::npos);
+}
+
+TEST_F(ButtonSystemTest, PressShowsInSerialOutput) {
+    ButtonApp app(&sim_, &btn_);
+    app.begin();
+
+    btn_.press();
+    app.update();
+
+    std::string output = sim_.serialOutput();
+    EXPECT_NE(output.find("Button pressed!"), std::string::npos);
+    EXPECT_NE(output.find("count: 1"), std::string::npos);
+}
+
+TEST_F(ButtonSystemTest, MultiplePressesCountCorrectly) {
+    ButtonApp app(&sim_, &btn_);
+    app.begin();
+
+    for (int i = 0; i < 5; ++i) {
+        btn_.press();
+        app.update();
+        btn_.release();
+        app.update();
+    }
+
+    EXPECT_EQ(app.pressCount(), 5);
+
+    std::string output = sim_.serialOutput();
+    EXPECT_NE(output.find("count: 5"), std::string::npos);
+}
+
+TEST_F(ButtonSystemTest, HoldOnlyCountsOnce) {
+    ButtonApp app(&sim_, &btn_);
+    app.begin();
+
+    btn_.press();
+    for (int i = 0; i < 100; ++i) {
+        app.update();
+    }
+
+    EXPECT_EQ(app.pressCount(), 1);
+}
+
+TEST_F(ButtonSystemTest, RapidPressReleaseCycle) {
+    ButtonApp app(&sim_, &btn_);
+    app.begin();
+
+    // Simulate rapid button mashing
+    for (int i = 0; i < 50; ++i) {
+        btn_.press();
+        app.update();
+        btn_.release();
+        app.update();
+    }
+
+    EXPECT_EQ(app.pressCount(), 50);
+}
+
+TEST_F(ButtonSystemTest, BouncyButtonWithSettling) {
+    ButtonSim bouncy_btn(5);  // 5 reads of bounce
+    bouncy_btn.setSeed(42);
+    ButtonApp app(&sim_, &bouncy_btn);
+    app.begin();
+
+    bouncy_btn.press();
+
+    // During bounce, we may get spurious edges.
+    // After settling, one press should eventually register.
+    for (int i = 0; i < 20; ++i) {
+        app.update();
+    }
+
+    // At least one press should have registered
+    EXPECT_GE(app.pressCount(), 1);
+}

templates/button/test/test_system.cpp.tmpl

@@ -0,0 +1,31 @@
+/*
+ * test_system.cpp -- Your system tests go here.
+ *
+ * This file is YOURS. Anvil will never overwrite it.
+ * The button example tests are in test_button_app.cpp.
+ *
+ * System tests use SimHal and ButtonSim to exercise real application
+ * logic against simulated hardware. See test_button_app.cpp for examples.
+ */
+
+#include <gtest/gtest.h>
+
+#include "mock_arduino.h"
+#include "hal.h"
+#include "sim_hal.h"
+#include "button_sim.h"
+#include "{{PROJECT_NAME}}_app.h"
+
+// Example: add your own system tests below
+// TEST(MySystemTests, DescribeWhatItTests) {
+//     mock_arduino_reset();
+//     SimHal sim;
+//     ButtonSim btn(0);  // 0 = no bounce
+//
+//     ButtonApp app(&sim, &btn);
+//     app.begin();
+//
+//     btn.press();
+//     app.update();
+//     EXPECT_EQ(app.pressCount(), 1);
+// }

templates/button/test/test_unit.cpp.tmpl

@@ -0,0 +1,34 @@
+/*
+ * test_unit.cpp -- Your unit tests go here.
+ *
+ * This file is YOURS. Anvil will never overwrite it.
+ * The button example tests are in test_button_app.cpp.
+ *
+ * Unit tests use MockHal and ButtonMock to verify exact behavior
+ * without real hardware. See test_button_app.cpp for examples.
+ */
+
+#include <gtest/gtest.h>
+#include <gmock/gmock.h>
+
+#include "hal.h"
+#include "mock_hal.h"
+#include "button_mock.h"
+#include "{{PROJECT_NAME}}_app.h"
+
+using ::testing::_;
+using ::testing::AnyNumber;
+using ::testing::Return;
+
+// Example: add your own tests below
+// TEST(MyTests, DescribeWhatItTests) {
+//     ::testing::NiceMock<MockHal> mock;
+//     ButtonMock btn;
+//
+//     ButtonApp app(&mock, &btn);
+//     app.begin();
+//
+//     btn.setPressed(true);
+//     app.update();
+//     EXPECT_EQ(app.pressCount(), 1);
+// }

tests/test_template_button.rs

@@ -0,0 +1,400 @@
+use anvil::commands;
+use anvil::library;
+use anvil::project::config::ProjectConfig;
+use anvil::templates::{TemplateManager, TemplateContext};
+use std::fs;
+use tempfile::TempDir;
+
+// ==========================================================================
+// Template listing and metadata
+// ==========================================================================
+
+#[test]
+fn test_list_templates_includes_button() {
+    let templates = TemplateManager::list_templates();
+    assert!(
+        templates.iter().any(|t| t.name == "button"),
+        "Should list button template"
+    );
+}
+
+#[test]
+fn test_button_template_exists() {
+    assert!(TemplateManager::template_exists("button"));
+}
+
+#[test]
+fn test_button_is_not_default() {
+    let templates = TemplateManager::list_templates();
+    let btn = templates.iter().find(|t| t.name == "button").unwrap();
+    assert!(!btn.is_default);
+}
+
+#[test]
+fn test_button_lists_button_library() {
+    let templates = TemplateManager::list_templates();
+    let btn = templates.iter().find(|t| t.name == "button").unwrap();
+    assert!(btn.libraries.contains(&"button".to_string()));
+}
+
+#[test]
+fn test_button_lists_digital_capability() {
+    let templates = TemplateManager::list_templates();
+    let btn = templates.iter().find(|t| t.name == "button").unwrap();
+    assert!(btn.board_capabilities.contains(&"digital".to_string()));
+}
+
+// ==========================================================================
+// Composed metadata
+// ==========================================================================
+
+#[test]
+fn test_button_composed_meta_exists() {
+    let meta = TemplateManager::composed_meta("button");
+    assert!(meta.is_some(), "Button should have composed metadata");
+}
+
+#[test]
+fn test_button_composed_meta_base_is_basic() {
+    let meta = TemplateManager::composed_meta("button").unwrap();
+    assert_eq!(meta.base, "basic");
+}
+
+#[test]
+fn test_button_composed_meta_requires_button_lib() {
+    let meta = TemplateManager::composed_meta("button").unwrap();
+    assert!(meta.libraries.contains(&"button".to_string()));
+}
+
+#[test]
+fn test_button_composed_meta_has_pin_defaults() {
+    let meta = TemplateManager::composed_meta("button").unwrap();
+    assert!(
+        !meta.pins.is_empty(),
+        "Should have pin defaults"
+    );
+}
+
+#[test]
+fn test_button_pins_for_uno() {
+    let meta = TemplateManager::composed_meta("button").unwrap();
+    let pins = meta.pins_for_board("uno");
+    assert_eq!(pins.len(), 1);
+    assert_eq!(pins[0].name, "button_signal");
+    assert_eq!(pins[0].pin, "2");
+    assert_eq!(pins[0].mode, "input");
+}
+
+#[test]
+fn test_button_pins_fallback_to_default() {
+    let meta = TemplateManager::composed_meta("button").unwrap();
+    // "micro" is not explicitly listed, should fall back to "default"
+    let pins = meta.pins_for_board("micro");
+    assert!(!pins.is_empty());
+    assert!(pins.iter().any(|p| p.name == "button_signal"));
+}
+
+// ==========================================================================
+// Template extraction
+// ==========================================================================
+
+fn extract_button(name: &str) -> TempDir {
+    let tmp = TempDir::new().unwrap();
+    let ctx = TemplateContext {
+        project_name: name.to_string(),
+        anvil_version: "1.0.0".to_string(),
+        board_name: "uno".to_string(),
+        fqbn: "arduino:avr:uno".to_string(),
+        baud: 115200,
+    };
+    TemplateManager::extract("button", tmp.path(), &ctx).unwrap();
+    // Record template name in config, same as create_project does
+    let mut config = ProjectConfig::load(tmp.path()).unwrap();
+    config.project.template = "button".to_string();
+    config.save(tmp.path()).unwrap();
+    tmp
+}
+
+#[test]
+fn test_button_has_basic_scaffold() {
+    let tmp = extract_button("btn");
+    // Basic scaffold from base template
+    assert!(tmp.path().join("lib/hal/hal.h").exists());
+    assert!(tmp.path().join("lib/hal/hal_arduino.h").exists());
+    assert!(tmp.path().join("test/mocks/mock_hal.h").exists());
+    assert!(tmp.path().join("test/mocks/sim_hal.h").exists());
+    assert!(tmp.path().join("test/CMakeLists.txt").exists());
+}
+
+#[test]
+fn test_button_has_button_app() {
+    let tmp = extract_button("btn");
+    let app = tmp.path().join("lib/app/btn_app.h");
+    assert!(app.exists(), "Should have button app header");
+
+    let content = fs::read_to_string(&app).unwrap();
+    assert!(content.contains("class ButtonApp"), "Should define ButtonApp");
+    assert!(content.contains("isPressed"), "Should use button interface");
+    assert!(content.contains("was_pressed_"), "Should track previous state");
+    assert!(content.contains("press_count_"), "Should count presses");
+    assert!(content.contains("serialPrintln"), "Should print to serial");
+}
+
+#[test]
+fn test_button_app_replaces_basic_blink() {
+    let tmp = extract_button("btn");
+    let app = tmp.path().join("lib/app/btn_app.h");
+    let content = fs::read_to_string(&app).unwrap();
+
+    // Should NOT contain basic template's BlinkApp
+    assert!(!content.contains("BlinkApp"), "Should not have BlinkApp");
+    assert!(content.contains("ButtonApp"), "Should have ButtonApp");
+}
+
+#[test]
+fn test_button_has_button_sketch() {
+    let tmp = extract_button("btn");
+    let sketch = tmp.path().join("btn/btn.ino");
+    assert!(sketch.exists(), "Sketch should exist");
+
+    let content = fs::read_to_string(&sketch).unwrap();
+    assert!(content.contains("button_digital.h"), "Should include button driver");
+    assert!(content.contains("ButtonDigital"), "Should create ButtonDigital");
+    assert!(content.contains("ButtonApp"), "Should create ButtonApp");
+}
+
+#[test]
+fn test_button_sketch_replaces_basic_sketch() {
+    let tmp = extract_button("btn");
+    let sketch = tmp.path().join("btn/btn.ino");
+    let content = fs::read_to_string(&sketch).unwrap();
+
+    assert!(!content.contains("BlinkApp"), "Should not reference BlinkApp");
+    assert!(content.contains("ButtonApp"), "Should reference ButtonApp");
+}
+
+#[test]
+fn test_button_has_managed_example_tests() {
+    let tmp = extract_button("btn");
+    let test_file = tmp.path().join("test/test_button_app.cpp");
+    assert!(test_file.exists(), "Should have managed test file");
+
+    let content = fs::read_to_string(&test_file).unwrap();
+    assert!(content.contains("MANAGED BY ANVIL"), "Should be marked as managed");
+    assert!(content.contains("ButtonUnitTest"), "Should have unit test fixture");
+    assert!(content.contains("ButtonSystemTest"), "Should have system test fixture");
+}
+
+#[test]
+fn test_button_has_student_unit_starter() {
+    let tmp = extract_button("btn");
+    let test_file = tmp.path().join("test/test_unit.cpp");
+    assert!(test_file.exists());
+
+    let content = fs::read_to_string(&test_file).unwrap();
+    assert!(content.contains("YOURS"), "Should be marked as student-owned");
+    assert!(content.contains("button_mock.h"), "Should include button mock");
+    assert!(content.contains("btn_app.h"), "Should include project app");
+}
+
+#[test]
+fn test_button_has_student_system_starter() {
+    let tmp = extract_button("btn");
+    let test_file = tmp.path().join("test/test_system.cpp");
+    assert!(test_file.exists());
+
+    let content = fs::read_to_string(&test_file).unwrap();
+    assert!(content.contains("YOURS"), "Should be marked as student-owned");
+    assert!(content.contains("button_sim.h"), "Should include button sim");
+}
+
+#[test]
+fn test_button_no_template_toml_in_output() {
+    let tmp = extract_button("btn");
+    assert!(
+        !tmp.path().join("template.toml").exists(),
+        "template.toml should not be extracted to output"
+    );
+}
+
+#[test]
+fn test_button_preserves_cmake() {
+    let tmp = extract_button("btn");
+    let cmake = tmp.path().join("test/CMakeLists.txt");
+    assert!(cmake.exists(), "CMakeLists.txt should survive overlay");
+}
+
+#[test]
+fn test_button_variable_substitution() {
+    let tmp = extract_button("mybutton");
+
+    // Sketch should use project name
+    let sketch = tmp.path().join("mybutton/mybutton.ino");
+    let content = fs::read_to_string(&sketch).unwrap();
+    assert!(content.contains("mybutton_app.h"), "Should substitute project name");
+    assert!(!content.contains("{{PROJECT_NAME}}"), "No unresolved placeholders");
+
+    // App header should use project name
+    let app = tmp.path().join("lib/app/mybutton_app.h");
+    assert!(app.exists(), "App header should use project name");
+
+    // Test files should use project name
+    let test_file = tmp.path().join("test/test_button_app.cpp");
+    let test_content = fs::read_to_string(&test_file).unwrap();
+    assert!(test_content.contains("mybutton_app.h"), "Test should include project app");
+    assert!(!test_content.contains("{{PROJECT_NAME}}"), "No unresolved placeholders");
+}
+
+#[test]
+fn test_button_all_files_ascii() {
+    let tmp = extract_button("btn");
+    for entry in walkdir(tmp.path()) {
+        let content = fs::read_to_string(&entry).unwrap_or_default();
+        for (line_num, line) in content.lines().enumerate() {
+            for (col, ch) in line.chars().enumerate() {
+                assert!(
+                    ch.is_ascii(),
+                    "Non-ASCII in {} at {}:{}: U+{:04X}",
+                    entry.display(),
+                    line_num + 1, col + 1, ch as u32
+                );
+            }
+        }
+    }
+}
+
+// ==========================================================================
+// C++ API compatibility: test file references valid sensor methods
+// ==========================================================================
+
+#[test]
+fn test_template_button_tests_use_valid_button_api() {
+    let tmp = extract_button("btn");
+
+    // Extract the button library so we can check method names
+    library::extract_library("button", tmp.path()).unwrap();
+
+    // Read mock and sim headers to build the set of valid methods
+    let mock_h = fs::read_to_string(
+        tmp.path().join("lib/drivers/button/button_mock.h")
+    ).unwrap();
+    let sim_h = fs::read_to_string(
+        tmp.path().join("lib/drivers/button/button_sim.h")
+    ).unwrap();
+
+    let test_file = fs::read_to_string(
+        tmp.path().join("test/test_button_app.cpp")
+    ).unwrap();
+
+    // Check that test calls methods that exist in mock or sim
+    let expected_methods = ["isPressed", "setPressed", "press", "release", "setSeed", "setBounceReads"];
+    for method in &expected_methods {
+        let in_mock = mock_h.contains(method);
+        let in_sim = sim_h.contains(method);
+        let in_test = test_file.contains(method);
+        if in_test {
+            assert!(
+                in_mock || in_sim,
+                "Test uses {}() but it is not in mock or sim headers",
+                method
+            );
+        }
+    }
+}
+
+// ==========================================================================
+// Full flow: new project with button template
+// ==========================================================================
+
+#[test]
+fn test_button_full_flow() {
+    let tmp = extract_button("btn_flow");
+
+    // Install the button library (as anvil new --template button would)
+    let meta = library::find_library("button").unwrap();
+    library::extract_library("button", tmp.path()).unwrap();
+
+    let mut config = ProjectConfig::load(tmp.path()).unwrap();
+    config.libraries.insert("button".to_string(), meta.version.clone());
+    let driver_include = format!("lib/drivers/{}", meta.name);
+    if !config.build.include_dirs.contains(&driver_include) {
+        config.build.include_dirs.push(driver_include);
+    }
+    config.save(tmp.path()).unwrap();
+
+    // Assign pin
+    let dir_str = tmp.path().to_string_lossy().to_string();
+    commands::pin::assign_pin(
+        "button_signal", "2",
+        Some("input"),
+        None,
+        Some(&dir_str),
+    ).unwrap();
+
+    // Verify everything is in place
+    let config_after = ProjectConfig::load(tmp.path()).unwrap();
+    assert!(config_after.libraries.contains_key("button"));
+    let board_pins = config_after.pins.get("uno").unwrap();
+    assert!(board_pins.assignments.contains_key("button_signal"));
+
+    // Files exist
+    assert!(tmp.path().join("lib/drivers/button/button.h").exists());
+    assert!(tmp.path().join("lib/drivers/button/button_digital.h").exists());
+    assert!(tmp.path().join("lib/drivers/button/button_mock.h").exists());
+    assert!(tmp.path().join("lib/drivers/button/button_sim.h").exists());
+    assert!(tmp.path().join("test/test_button.cpp").exists());
+    assert!(tmp.path().join("test/test_button_app.cpp").exists());
+    assert!(tmp.path().join("lib/app/btn_flow_app.h").exists());
+}
+
+#[test]
+fn test_button_config_records_template_name() {
+    let tmp = extract_button("tmpl_name");
+    let config = ProjectConfig::load(tmp.path()).unwrap();
+    assert_eq!(config.project.template.as_str(), "button");
+}
+
+#[test]
+fn test_button_audit_clean_after_full_setup() {
+    let tmp = extract_button("audit_btn");
+
+    let meta = library::find_library("button").unwrap();
+    library::extract_library("button", tmp.path()).unwrap();
+
+    let mut config = ProjectConfig::load(tmp.path()).unwrap();
+    config.libraries.insert("button".to_string(), meta.version.clone());
+    config.save(tmp.path()).unwrap();
+
+    let dir_str = tmp.path().to_string_lossy().to_string();
+    commands::pin::assign_pin(
+        "button_signal", "2",
+        Some("input"),
+        None,
+        Some(&dir_str),
+    ).unwrap();
+
+    // Audit should pass cleanly
+    commands::pin::audit_pins(None, false, Some(&dir_str)).unwrap();
+}
+
+// ==========================================================================
+// Helper: walk all files in a directory tree
+// ==========================================================================
+
+fn walkdir(root: &std::path::Path) -> Vec<std::path::PathBuf> {
+    let mut files = Vec::new();
+    fn walk(dir: &std::path::Path, out: &mut Vec<std::path::PathBuf>) {
+        if let Ok(entries) = fs::read_dir(dir) {
+            for entry in entries.flatten() {
+                let path = entry.path();
+                if path.is_dir() {
+                    walk(&path, out);
+                } else if path.is_file() {
+                    out.push(path);
+                }
+            }
+        }
+    }
+    walk(root, &mut files);
+    files
+}