#410: add unit test for ICommandSystem::addWithCheck()

Confirm that the canExecute() method returns the correct value based on
the check function.

include/icommandsystem.h

@@ -285,7 +285,14 @@ class ICommandSystem: public RegisterableModule
     /// Returns true if the named command exists
     virtual bool commandExists(const std::string& name) = 0;
 
-    /// Return true if the named command is currently able to execute
+    /**
+     * @brief Check if the named command is currently runnable.
+     *
+     * This is just a signal to the UI that a command should be disabled; the
+     * command system does NOT guarantee that a command for which canExecute()
+     * returns false won't actually be invoked by a subsequent call to
+     * executeCommand().
+     */
     virtual bool canExecute(const std::string& name) const = 0;
 
 	/**

test/CommandSystem.cpp

@@ -16,7 +16,7 @@ TEST_F(CommandSystemTest, AddAndRunCommand)
     int runCount = 0;
 
     // Add a command which just logs the number of times it is called
-    EXPECT_FALSE(GlobalCommandSystem().commandExists("testRunCount"));
+    ASSERT_FALSE(GlobalCommandSystem().commandExists("testRunCount"));
     GlobalCommandSystem().addCommand("testRunCount",
                                      [&](const cmd::ArgumentList&) { ++runCount; });
     EXPECT_TRUE(GlobalCommandSystem().commandExists("testRunCount"));
@@ -28,4 +28,23 @@ TEST_F(CommandSystemTest, AddAndRunCommand)
     EXPECT_EQ(runCount, 2);
 }
 
+TEST_F(CommandSystemTest, AddCheckedCommand)
+{
+    const char* COMMAND_NAME = "testCheckedCommand";
+    bool commandEnabled = false;
+
+    // Add a command which is conditionally enabled based on our variable flag
+    ASSERT_FALSE(GlobalCommandSystem().commandExists(COMMAND_NAME));
+    GlobalCommandSystem().addWithCheck(
+        COMMAND_NAME, [](const cmd::ArgumentList&) {}, [&]() { return commandEnabled; }
+    );
+
+    // The flag should control the executability of the command
+    EXPECT_FALSE(GlobalCommandSystem().canExecute(COMMAND_NAME));
+    commandEnabled = true;
+    EXPECT_TRUE(GlobalCommandSystem().canExecute(COMMAND_NAME));
+    commandEnabled = false;
+    EXPECT_FALSE(GlobalCommandSystem().canExecute(COMMAND_NAME));
+}
+
 }