First Commit

Projects/02_ClassroomTimer/CMakeLists.txt

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+cmake_minimum_required(VERSION 3.16)
+project(ClassroomTimer VERSION 1.0 LANGUAGES CXX)
+set(CMAKE_AUTOMOC ON)
+set(CMAKE_AUTOUIC ON)
+set(CMAKE_CXX_STANDARD 14)
+set(CMAKE_CXX_STANDARD_REQUIRED ON)
+set(CMAKE_CXX_EXTENSIONS OFF)
+find_package(QT NAMES Qt6 Qt5 REQUIRED COMPONENTS Widgets)
+find_package(Qt${QT_VERSION_MAJOR} REQUIRED COMPONENTS Widgets)
+if(QT_VERSION_MAJOR EQUAL 5 AND Qt5Core_VERSION VERSION_LESS 5.14.2)
+    message(FATAL_ERROR "Qt 5.14.2 or newer is required.")
+endif()
+if(QT_VERSION_MAJOR EQUAL 6)
+    set(CMAKE_CXX_STANDARD 17)
+endif()
+if(MSVC)
+    add_compile_options(/utf-8)
+else()
+    add_compile_options(-Wall -Wextra -Wpedantic)
+endif()
+add_executable(ClassroomTimer WIN32 main.cpp appearance.h mainwindow.cpp mainwindow.h countdown.cpp countdown.h mainwindow.ui)
+target_link_libraries(ClassroomTimer PRIVATE Qt${QT_VERSION_MAJOR}::Widgets)
+option(BUILD_TEACHING_TESTS "Build teaching project tests" OFF)
+if(BUILD_TEACHING_TESTS)
+    enable_testing()
+    find_package(Qt${QT_VERSION_MAJOR} REQUIRED COMPONENTS Test)
+    add_executable(test_ClassroomTimer tests/test_ClassroomTimer.cpp mainwindow.cpp mainwindow.h
+                   countdown.cpp countdown.h mainwindow.ui)
+    target_include_directories(test_ClassroomTimer PRIVATE ${CMAKE_CURRENT_SOURCE_DIR})
+    target_link_libraries(test_ClassroomTimer PRIVATE Qt${QT_VERSION_MAJOR}::Widgets Qt${QT_VERSION_MAJOR}::Test)
+    add_test(NAME ClassroomTimer COMMAND test_ClassroomTimer -platform offscreen)
+endif()
+

Projects/02_ClassroomTimer/ClassroomTimer.pro

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+QT += widgets
+CONFIG += c++14
+greaterThan(QT_MAJOR_VERSION, 5): CONFIG += c++17
+TEMPLATE = app
+TARGET = ClassroomTimer
+SOURCES += main.cpp mainwindow.cpp countdown.cpp
+HEADERS += mainwindow.h countdown.h
+FORMS += mainwindow.ui
+msvc: QMAKE_CXXFLAGS += /utf-8
+

Projects/02_ClassroomTimer/README.md

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+# 项目二：课堂计时器
+
+适合第3—4章讲解信号槽、定时器、状态变化和数值输入。可用于限时练习、分组讨论与课堂展示。
+
+## 功能与操作
+
+时长范围为 0 到 23:59:59，但零时长不能开始。默认时长为 5 分钟。
+
+- 开始：从设置的时长开始计时。
+- 暂停：保存此刻的剩余时间。
+- 继续：从保存的剩余时间接着计时。
+- 复位：停止本轮计时，并恢复到设置的完整时长。
+- 重新开始：到时后开始新的一轮。
+- 全屏显示：便于投影；按 Esc 退出全屏。
+- 到时提示：显示“时间到”，并可播放一次系统提示音。能否听到提示音取决于系统声音设置。
+
+运行中和暂停时，时长输入框均被锁定；先复位，再修改时长。
+
+## 课堂任务
+
+先连接开始按钮和 QTimer，让学生观察 timeout 信号重复到达。随后故意安排一次较慢的界面处理，讨论“每次 timeout 减 100 毫秒”为什么可能不准确。
+
+QTimer 在这个项目中每隔约 100 毫秒请求刷新显示。实际剩余时间由 QElapsedTimer 提供的经过时间计算，不依赖刷新次数。即使某次刷新较晚，下一次仍按实际经过的时间计算。
+
+讲解模型时可先使用确定的数值：总时长 10 秒，在第 2.5 秒暂停，还剩 7.5 秒；暂停 1 分钟后继续，剩余时间仍从 7.5 秒开始。
+
+## 核心数据
+
+Countdown 保存四项信息：完整时长、当前计时片段开始时的剩余量、该片段的开始时刻，以及状态。
+
+运行时：
+剩余毫秒 = max(0, 片段开始时的剩余毫秒 − 本片段已过去的毫秒)。
+
+暂停时先算出剩余毫秒并保存，再切换到 Paused。继续时只记录新的片段开始时刻，不恢复完整时长。
+
+界面显示秒数采用向上取整。还剩 1 毫秒时显示 1 秒，真正到时才显示 0，避免“已经显示零但还没结束”的现象。
+
+## 状态与操作
+
+| 当前状态 | 开始按钮 | 暂停按钮 | 时长输入 |
+|---|---|---|---|
+| Ready | 开始，零时长除外 | 不可用 | 可修改 |
+| Running | 不可用 | 暂停 | 锁定 |
+| Paused | 继续 | 不可用 | 锁定 |
+| Finished | 重新开始 | 不可用 | 可修改 |
+
+refreshDisplay 根据同一个状态统一设置按钮，避免在多个槽函数中分别修改后产生矛盾。
+
+## 学生练习
+
+1. 加入 1、3、5 分钟快捷设置按钮，并遵守运行中不能改变时长的规则。
+2. 最后 10 秒改变数字颜色，到时和复位后恢复正确颜色。
+3. 增加本轮标题，例如“独立练习”。标题变化不应重新开始计时。
+
+## 验收用例
+
+- 设置 1 秒并开始：到时显示 00:00:00，暂停按钮不可用。
+- 运行时连续触发开始操作：不会重新计算起点。
+- 暂停后等待：剩余时间保持不变；继续后接着减少。
+- 运行或暂停时点击复位：回到原设置时长，并允许修改。
+- 设置零时长：不能开始。
+- 模型两次更新之间跨过截止时间：剩余量直接归零，不出现负数。
+
+自动化测试通过传入固定的毫秒数检查计时规则；另有真实按钮测试确认计时模型与界面的连接。
+

Projects/02_ClassroomTimer/appearance.h

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+#pragma once
+#include <QApplication>
+#include <QFont>
+#include <QStyleFactory>
+
+inline void applyAppearance(QApplication &app)
+{
+    app.setStyle(QStyleFactory::create(QStringLiteral("Fusion")));
+    app.setFont(QFont(QStringLiteral("Microsoft YaHei UI"), 11));
+    app.setStyleSheet(QStringLiteral(
+        "QMainWindow { background: #f5f7fb; }"
+        "QLabel { color: #23364c; }"
+        "QLabel#titleLabel { font-size: 27px; font-weight: bold; color: #173b63; }"
+        "QLabel#subtitleLabel, QLabel#helpLabel { color: #52657a; }"
+        "QGroupBox { background: white; border: 1px solid #d6e0eb;"
+        " border-radius: 8px; margin-top: 12px; padding: 18px 12px 12px; }"
+        "QGroupBox::title { subcontrol-origin: margin; left: 12px; padding: 0 6px; }"
+        "QLineEdit, QSpinBox, QComboBox { min-height: 32px; padding: 3px 8px; }"
+        "QLineEdit, QSpinBox, QComboBox, QPlainTextEdit, QListWidget"
+        " { background: white; color: #23364c; }"
+        "QPushButton { min-height: 34px; padding: 4px 14px; }"
+        "QPushButton#convertButton, QPushButton#startButton, QPushButton#drawButton,"
+        " QPushButton#applyButton, QPushButton#groupsButton { background: #255c93;"
+        " color: white; border: 1px solid #255c93; border-radius: 5px; }"
+        "QPushButton:disabled, QPushButton#convertButton:disabled,"
+        " QPushButton#startButton:disabled, QPushButton#drawButton:disabled,"
+        " QPushButton#applyButton:disabled, QPushButton#groupsButton:disabled"
+        " { color: #8995a3; background: #e6ebf1; border-color: #d6e0eb; }"
+        "QLabel#statusLabel { color: #185376; }"
+        "QLineEdit#resultEdit { font-size: 23px; min-height: 45px; color: #175e53; }"
+        "QLabel#timeLabel { font: bold 76px 'Consolas'; color: #173b63; }"
+        "QProgressBar { border: 1px solid #d6e0eb; border-radius: 6px; height: 14px; }"
+        "QProgressBar::chunk { background: #2b8a7d; border-radius: 5px; }"));
+}

Projects/02_ClassroomTimer/countdown.cpp

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+#include "countdown.h"
+
+Countdown::Countdown(qint64 durationMs)
+    : m_duration(qMax<qint64>(0, durationMs)), m_remainingAtStart(m_duration)
+{
+}
+
+bool Countdown::setDuration(qint64 durationMs)
+{
+    if (m_state == State::Running || m_state == State::Paused || durationMs < 0)
+        return false;
+    m_duration = durationMs;
+    reset();
+    return true;
+}
+
+void Countdown::start(qint64 nowMs)
+{
+    if (m_state == State::Running || m_duration <= 0)
+        return;
+    if (m_state != State::Paused)
+        m_remainingAtStart = m_duration;
+    m_segmentStarted = nowMs;
+    m_state = State::Running;
+}
+
+qint64 Countdown::remaining(qint64 nowMs) const
+{
+    if (m_state == State::Finished)
+        return 0;
+    if (m_state != State::Running)
+        return m_remainingAtStart;
+    const qint64 elapsed = qMax<qint64>(0, nowMs - m_segmentStarted);
+    return qMax<qint64>(0, m_remainingAtStart - elapsed);
+}
+
+void Countdown::update(qint64 nowMs)
+{
+    if (m_state == State::Running && remaining(nowMs) == 0) {
+        m_remainingAtStart = 0;
+        m_state = State::Finished;
+    }
+}
+
+void Countdown::pause(qint64 nowMs)
+{
+    update(nowMs);
+    if (m_state != State::Running)
+        return;
+    // 先保存这一刻的剩余时间，再切换状态，暂停期间不继续扣减。
+    m_remainingAtStart = remaining(nowMs);
+    m_state = State::Paused;
+}
+
+void Countdown::reset()
+{
+    m_remainingAtStart = m_duration;
+    m_segmentStarted = 0;
+    m_state = State::Ready;
+}
+

Projects/02_ClassroomTimer/countdown.h

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+#pragma once
+#include <QtGlobal>
+
+// 界面负责取得当前时间，模型只负责计算；测试可传入确定的毫秒数。
+class Countdown {
+public:
+    enum class State { Ready, Running, Paused, Finished };
+    explicit Countdown(qint64 durationMs = 300000);
+    bool setDuration(qint64 durationMs);
+    void start(qint64 nowMs);
+    void pause(qint64 nowMs);
+    void reset();
+    void update(qint64 nowMs);
+    qint64 remaining(qint64 nowMs) const;
+    qint64 duration() const { return m_duration; }
+    State state() const { return m_state; }
+private:
+    qint64 m_duration;
+    qint64 m_remainingAtStart;
+    qint64 m_segmentStarted = 0;
+    State m_state = State::Ready;
+};
+

Projects/02_ClassroomTimer/main.cpp

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+#include "mainwindow.h"
+#include "appearance.h"
+#include <QApplication>
+#include <QFont>
+#include <QStyleFactory>
+
+int main(int argc, char *argv[])
+{
+#if QT_VERSION < QT_VERSION_CHECK(6, 0, 0)
+    QApplication::setAttribute(Qt::AA_EnableHighDpiScaling);
+    QApplication::setAttribute(Qt::AA_UseHighDpiPixmaps);
+#endif
+    QApplication app(argc, argv);
+    applyAppearance(app);
+    MainWindow window;
+    window.show();
+    return app.exec();
+}
+

Projects/02_ClassroomTimer/mainwindow.cpp

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+#include "mainwindow.h"
+#include "ui_mainwindow.h"
+#include <QApplication>
+#include <QShortcut>
+
+MainWindow::MainWindow(QWidget *parent)
+    : QMainWindow(parent), ui(new Ui::MainWindow)
+{
+    ui->setupUi(this);
+    m_clock.start();
+    m_refreshTimer.setInterval(100);
+    connect(&m_refreshTimer, &QTimer::timeout, this, &MainWindow::refreshDisplay);
+    for (QSpinBox *spin : {ui->hoursSpin, ui->minutesSpin, ui->secondsSpin})
+        connect(spin, static_cast<void (QSpinBox::*)(int)>(&QSpinBox::valueChanged),
+                this, &MainWindow::durationChanged);
+    connect(ui->startButton, &QPushButton::clicked, this, [this] {
+        m_countdown.start(m_clock.elapsed());
+        refreshDisplay();
+    });
+    connect(ui->pauseButton, &QPushButton::clicked, this, [this] {
+        const auto previousState = m_countdown.state();
+        m_countdown.pause(m_clock.elapsed());
+        if (previousState == Countdown::State::Running
+                && m_countdown.state() == Countdown::State::Finished
+                && ui->soundCheck->isChecked())
+            QApplication::beep();
+        refreshDisplay();
+    });
+    connect(ui->resetButton, &QPushButton::clicked, this, [this] {
+        m_countdown.reset();
+        refreshDisplay();
+    });
+    connect(ui->fullscreenButton, &QPushButton::clicked, this, [this] {
+        if (isFullScreen()) showNormal(); else showFullScreen();
+        ui->fullscreenButton->setText(isFullScreen() ? tr("退出全屏") : tr("全屏显示"));
+    });
+    auto *escape = new QShortcut(QKeySequence(Qt::Key_Escape), this);
+    connect(escape, &QShortcut::activated, this, [this] {
+        if (isFullScreen()) {
+            showNormal();
+            ui->fullscreenButton->setText(tr("全屏显示"));
+        }
+    });
+    durationChanged();
+}
+
+MainWindow::~MainWindow() { delete ui; }
+
+void MainWindow::durationChanged()
+{
+    const qint64 seconds = ui->hoursSpin->value() * 3600
+        + ui->minutesSpin->value() * 60 + ui->secondsSpin->value();
+    m_countdown.setDuration(seconds * 1000);
+    refreshDisplay();
+}
+
+void MainWindow::refreshDisplay()
+{
+    const qint64 now = m_clock.elapsed();
+    const auto previousState = m_countdown.state();
+    m_countdown.update(now);
+    const auto state = m_countdown.state();
+    const bool running = state == Countdown::State::Running;
+    const bool paused = state == Countdown::State::Paused;
+    if (running && !m_refreshTimer.isActive()) m_refreshTimer.start();
+    if (!running) m_refreshTimer.stop();
+    const qint64 remaining = m_countdown.remaining(now);
+    // 向上取整：还剩 1 毫秒时显示 1 秒，真正到时才显示零。
+    const qint64 seconds = (remaining + 999) / 1000;
+    ui->timeLabel->setText(QStringLiteral("%1:%2:%3")
+        .arg(seconds / 3600, 2, 10, QLatin1Char('0'))
+        .arg((seconds / 60) % 60, 2, 10, QLatin1Char('0'))
+        .arg(seconds % 60, 2, 10, QLatin1Char('0')));
+    ui->progressBar->setValue(m_countdown.duration() == 0 ? 0
+        : static_cast<int>(remaining * 1000 / m_countdown.duration()));
+    ui->durationGroup->setEnabled(!running && !paused);
+    ui->startButton->setEnabled(!running && m_countdown.duration() > 0);
+    ui->pauseButton->setEnabled(running);
+    ui->startButton->setText(paused ? tr("继续") :
+        state == Countdown::State::Finished ? tr("重新开始") : tr("开始"));
+    if (running) ui->statusLabel->setText(tr("正在计时"));
+    else if (paused) ui->statusLabel->setText(tr("已暂停 · 点击“继续”接着计时"));
+    else if (state == Countdown::State::Finished)
+        ui->statusLabel->setText(tr("时间到！本轮计时已结束。"));
+    else ui->statusLabel->setText(m_countdown.duration() > 0
+        ? tr("准备就绪 · 点击“开始”") : tr("请先设置大于 0 的时长。"));
+    if (previousState == Countdown::State::Running && state == Countdown::State::Finished
+            && ui->soundCheck->isChecked())
+        QApplication::beep();
+}
+

Projects/02_ClassroomTimer/mainwindow.h

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+#pragma once
+#include <QMainWindow>
+#include <QElapsedTimer>
+#include <QTimer>
+#include "countdown.h"
+namespace Ui { class MainWindow; }
+
+class MainWindow : public QMainWindow {
+    Q_OBJECT
+public:
+    explicit MainWindow(QWidget *parent = nullptr);
+    ~MainWindow() override;
+private:
+    Ui::MainWindow *ui;
+    Countdown m_countdown;
+    QElapsedTimer m_clock;
+    QTimer m_refreshTimer;
+    void durationChanged();
+    void refreshDisplay();
+};
+

Projects/02_ClassroomTimer/mainwindow.ui

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+<?xml version="1.0" encoding="UTF-8"?>
+<ui version="4.0">
+ <class>MainWindow</class>
+ <widget class="QMainWindow" name="MainWindow">
+  <property name="windowTitle">
+   <string>课堂计时器</string>
+  </property>
+  <property name="geometry">
+   <rect>
+    <x>0</x>
+    <y>0</y>
+    <width>820</width>
+    <height>650</height>
+   </rect>
+  </property>
+  <widget class="QWidget" name="centralwidget">
+   <layout class="QVBoxLayout" name="rootLayout">
+    <property name="spacing">
+     <number>12</number>
+    </property>
+    <property name="leftMargin">
+     <number>24</number>
+    </property>
+    <property name="topMargin">
+     <number>24</number>
+    </property>
+    <property name="rightMargin">
+     <number>24</number>
+    </property>
+    <property name="bottomMargin">
+     <number>24</number>
+    </property>
+    <item>
+     <widget class="QLabel" name="titleLabel">
+      <property name="text">
+       <string>课堂计时器</string>
+      </property>
+      <property name="textFormat">
+       <enum>Qt::PlainText</enum>
+      </property>
+     </widget>
+    </item>
+    <item>
+     <widget class="QLabel" name="subtitleLabel">
+      <property name="text">
+       <string>用于课堂练习、分组讨论与限时展示。</string>
+      </property>
+      <property name="textFormat">
+       <enum>Qt::PlainText</enum>
+      </property>
+      <property name="wordWrap">
+       <bool>true</bool>
+      </property>
+     </widget>
+    </item>
+    <item>
+     <widget class="QGroupBox" name="durationGroup">
+      <property name="title">
+       <string>设置时长</string>
+      </property>
+      <layout class="QGridLayout" name="durationLayout">
+       <property name="spacing">
+        <number>12</number>
+       </property>
+       <item row="0" column="0">
+        <widget class="QLabel" name="hoursSpinLabel">
+         <property name="text">
+          <string>小时</string>
+         </property>
+         <property name="textFormat">
+          <enum>Qt::PlainText</enum>
+         </property>
+        </widget>
+       </item>
+       <item row="1" column="0">
+        <widget class="QSpinBox" name="hoursSpin">
+         <property name="maximum">
+          <number>23</number>
+         </property>
+         <property name="value">
+          <number>0</number>
+         </property>
+        </widget>
+       </item>
+       <item row="0" column="1">
+        <widget class="QLabel" name="minutesSpinLabel">
+         <property name="text">
+          <string>分钟</string>
+         </property>
+         <property name="textFormat">
+          <enum>Qt::PlainText</enum>
+         </property>
+        </widget>
+       </item>
+       <item row="1" column="1">
+        <widget class="QSpinBox" name="minutesSpin">
+         <property name="maximum">
+          <number>59</number>
+         </property>
+         <property name="value">
+          <number>5</number>
+         </property>
+        </widget>
+       </item>
+       <item row="0" column="2">
+        <widget class="QLabel" name="secondsSpinLabel">
+         <property name="text">
+          <string>秒</string>
+         </property>
+         <property name="textFormat">
+          <enum>Qt::PlainText</enum>
+         </property>
+        </widget>
+       </item>
+       <item row="1" column="2">
+        <widget class="QSpinBox" name="secondsSpin">
+         <property name="maximum">
+          <number>59</number>
+         </property>
+         <property name="value">
+          <number>0</number>
+         </property>
+        </widget>
+       </item>
+      </layout>
+     </widget>
+    </item>
+    <item>
+     <widget class="QLabel" name="timeLabel">
+      <property name="text">
+       <string>00:05:00</string>
+      </property>
+      <property name="textFormat">
+       <enum>Qt::PlainText</enum>
+      </property>
+      <property name="alignment">
+       <set>Qt::AlignCenter</set>
+      </property>
+      <property name="minimumSize">
+       <size>
+        <width>0</width>
+        <height>135</height>
+       </size>
+      </property>
+     </widget>
+    </item>
+    <item>
+     <widget class="QProgressBar" name="progressBar">
+      <property name="maximum">
+       <number>1000</number>
+      </property>
+      <property name="value">
+       <number>1000</number>
+      </property>
+      <property name="textVisible">
+       <bool>false</bool>
+      </property>
+     </widget>
+    </item>
+    <item>
+     <widget class="QLabel" name="statusLabel">
+      <property name="text">
+       <string>准备就绪</string>
+      </property>
+      <property name="textFormat">
+       <enum>Qt::PlainText</enum>
+      </property>
+      <property name="alignment">
+       <set>Qt::AlignCenter</set>
+      </property>
+      <property name="minimumSize">
+       <size>
+        <width>0</width>
+        <height>45</height>
+       </size>
+      </property>
+     </widget>
+    </item>
+    <item>
+     <layout class="QHBoxLayout" name="timerActions">
+      <property name="spacing">
+       <number>12</number>
+      </property>
+      <item>
+       <widget class="QPushButton" name="startButton">
+        <property name="text">
+         <string>开始</string>
+        </property>
+       </widget>
+      </item>
+      <item>
+       <widget class="QPushButton" name="pauseButton">
+        <property name="text">
+         <string>暂停</string>
+        </property>
+       </widget>
+      </item>
+      <item>
+       <widget class="QPushButton" name="resetButton">
+        <property name="text">
+         <string>复位</string>
+        </property>
+       </widget>
+      </item>
+      <item>
+       <widget class="QPushButton" name="fullscreenButton">
+        <property name="text">
+         <string>全屏显示</string>
+        </property>
+       </widget>
+      </item>
+     </layout>
+    </item>
+    <item>
+     <widget class="QCheckBox" name="soundCheck">
+      <property name="text">
+       <string>到时播放系统提示音</string>
+      </property>
+      <property name="checked">
+       <bool>true</bool>
+      </property>
+     </widget>
+    </item>
+    <item>
+     <widget class="QLabel" name="helpLabel">
+      <property name="text">
+       <string>计时中和暂停时锁定时长；点击“复位”后可重新设置。全屏时按 Esc 返回。</string>
+      </property>
+      <property name="textFormat">
+       <enum>Qt::PlainText</enum>
+      </property>
+      <property name="wordWrap">
+       <bool>true</bool>
+      </property>
+     </widget>
+    </item>
+   </layout>
+  </widget>
+ </widget>
+ <resources />
+ <connections />
+</ui>

Projects/02_ClassroomTimer/tests/test_ClassroomTimer.cpp

@@ -0,0 +1,100 @@
+#include <QtTest>
+#include <QSpinBox>
+#include <QPushButton>
+#include <QLabel>
+#include <QCheckBox>
+#include "countdown.h"
+#include "mainwindow.h"
+#include <QApplication>
+#include <QDir>
+#include "appearance.h"
+
+static void savePreview(QWidget &window, const QString &fileName)
+{
+    const QString folder = QString::fromLocal8Bit(qgetenv("QT_TEACHING_SCREENSHOTS"));
+    if (folder.isEmpty()) return;
+    QDir().mkpath(folder);
+    window.show();
+    QApplication::processEvents();
+    QVERIFY(window.grab().save(QDir(folder).filePath(fileName)));
+}
+
+class TimerTest : public QObject {
+    Q_OBJECT
+private slots:
+    void initTestCase() { applyAppearance(*qApp); }
+    void pauseResumeAndDrift()
+    {
+        Countdown model(10000);
+        model.start(100);
+        model.start(500); // 重复开始不能重新计时。
+        QCOMPARE(model.remaining(2600), qint64(7500));
+        model.pause(2600);
+        QCOMPARE(model.remaining(90000), qint64(7500));
+        QVERIFY(!model.setDuration(2000));
+        model.start(100000);
+        QCOMPARE(model.remaining(102500), qint64(5000));
+        model.update(107500);
+        QVERIFY(model.state() == Countdown::State::Finished);
+        QCOMPARE(model.remaining(107500), qint64(0));
+        model.start(200000);
+        QCOMPARE(model.remaining(200000), qint64(10000));
+    }
+    void delayedRefreshAndReset()
+    {
+        Countdown model(5000);
+        model.start(0);
+        model.update(100);
+        model.update(4300);
+        QCOMPARE(model.remaining(4300), qint64(700));
+        model.update(9999);
+        QCOMPARE(model.remaining(9999), qint64(0));
+        QVERIFY(model.state() == Countdown::State::Finished);
+        model.reset();
+        QVERIFY(model.state() == Countdown::State::Ready);
+        QCOMPARE(model.remaining(9999), qint64(5000));
+    }
+    void zeroAndDeadlinePause()
+    {
+        Countdown model(0);
+        model.start(0);
+        QVERIFY(model.state() == Countdown::State::Ready);
+        QVERIFY(!model.setDuration(-1));
+        QVERIFY(model.setDuration(1000));
+        model.start(10);
+        model.pause(1010);
+        QVERIFY(model.state() == Countdown::State::Finished);
+    }
+    void uiWorkflow()
+    {
+        MainWindow w; w.show();
+        auto *start = w.findChild<QPushButton *>(QStringLiteral("startButton"));
+        auto *pause = w.findChild<QPushButton *>(QStringLiteral("pauseButton"));
+        auto *reset = w.findChild<QPushButton *>(QStringLiteral("resetButton"));
+        auto *minutes = w.findChild<QSpinBox *>(QStringLiteral("minutesSpin"));
+        auto *seconds = w.findChild<QSpinBox *>(QStringLiteral("secondsSpin"));
+        auto *time = w.findChild<QLabel *>(QStringLiteral("timeLabel"));
+        w.findChild<QCheckBox *>(QStringLiteral("soundCheck"))->setChecked(false);
+        savePreview(w, QStringLiteral("02_timer.png"));
+        minutes->setValue(0); seconds->setValue(1);
+        QTest::mouseClick(start, Qt::LeftButton);
+        QVERIFY(!minutes->isEnabled());
+        QTest::mouseClick(pause, Qt::LeftButton);
+        QCOMPARE(start->text(), QStringLiteral("继续"));
+        const QString pausedText = time->text();
+        QTest::qWait(150);
+        QCOMPARE(time->text(), pausedText);
+        QTest::mouseClick(start, Qt::LeftButton);
+        QTRY_COMPARE(time->text(), QStringLiteral("00:00:00"));
+        QVERIFY(w.findChild<QLabel *>(QStringLiteral("statusLabel"))->text().contains(QStringLiteral("时间到")));
+        QVERIFY(!pause->isEnabled());
+        QTest::mouseClick(reset, Qt::LeftButton);
+        QCOMPARE(time->text(), QStringLiteral("00:00:01"));
+        QVERIFY(minutes->isEnabled());
+        seconds->setValue(0);
+        QVERIFY(!start->isEnabled());
+    }
+};
+QTEST_MAIN(TimerTest)
+#include "test_ClassroomTimer.moc"
+

Projects/02_ClassroomTimer/tests/test_ClassroomTimer.pro

@@ -0,0 +1,11 @@
+QT += widgets testlib
+CONFIG += c++14 console testcase
+greaterThan(QT_MAJOR_VERSION, 5): CONFIG += c++17
+TEMPLATE = app
+TARGET = test_ClassroomTimer
+INCLUDEPATH += ..
+SOURCES += test_ClassroomTimer.cpp ../mainwindow.cpp ../countdown.cpp
+HEADERS += ../mainwindow.h ../countdown.h
+FORMS += ../mainwindow.ui
+msvc: QMAKE_CXXFLAGS += /utf-8
+