[utest]: [signal]:Standardized function comment blocks have been added.

Added comments to the utest for the signal module, including: test purpose,
usage scenarios, dependency configurations, expected outcomes, and expected
behaviors.

Signed-off-by: Mengchen Teng <[email protected]>

Author: Tm-C-mT

src/utest/signal_tc.c

@@ -17,6 +17,115 @@
  * case 8:rt_signal_kill, kill illegal thread, return failed (unused);
  * case 9:rt_signal_kill, kill illegal signo, return -RT_EINVAL;
  *
+ *
+ * Test Case Name: [rt_signal_tc]
+ *
+ * Test Objectives:
+ * - [rt_signal_install_test]: Verify the correctness of the rt_signal_install function's
+ * - functionality. The registration of the signal handler should be completed correctly.
+ * - Include Case1 and Case2.
+ *
+ * - [rt_signal_mask_test]: Verify the correctness of the rt_signal_unmask functions's
+ * - functionality. The signal handler will only be triggered when the signal is unmasked.
+ * - Include Case3.
+ *
+ * - [rt_signal_unmask_test]: Verify the correctness of the rt_signal_mask functions's
+ * - functionality. The signal handler will not be triggered when the signal is masked.
+ * - Include Case4.
+ *
+ * - [rt_signal_kill_test]: Verify the correctness of the rt_signal_kill function's
+ * - functionality. Signals should be sent to the specified thread correctly. Include
+ * - Case7, Case8 and Case9. But Case8 is currently unused.
+ *
+ * - [rt_signal_wait_test]: Verify signal delivery to a waiting thread. Include Case5.
+ *
+ * - [rt_signal_wait_test2]: Verify timeout behavior when waiting for a signal.
+ *
+ * Test Scenarios:
+ *
+ * - [rt_signal_install_test]: When the signal signo is greater than 0 and less than RT_SIG_MAX,
+ * - the rt_signal_install function can register the signal handler normally (i.e., the return
+ * - value is not equal to SIG_ERR). However, if signo is not within the above range, the
+ * - rt_signal_install function returns SIG_ERR.
+ *
+ * - [rt_signal_mask_test]: When signo is valid, the signal handler will first be successfully
+ * - registered via rt_signal_install, where receive_sig is assigned the value of the triggered
+ * - signal signo. After successful registration, the specified signal mask is unmasked using
+ * - rt_signal_unmask, and a signal is sent to rt_thread_self via rt_thread_kill. After a 1ms
+ * - delay, the signal callback function is triggered successfully, and the value of recive_sig
+ * - equals the value of signo.
+ *
+ * - [rt_signal_unmask_test]: When signo is valid, the signal handler will first be successfully
+ * - registered via rt_signal_install, where receive_sig is assigned the value of the triggered
+ * - signal signo. After successful registration, the specified signal mask is unmasked using
+ * - rt_signal_unmask, then masked again using rt_signal_mask. A signal is then sent to rt_thread_self
+ * - via rt_thread_kill. After a 1ms delay, the signal callback function is not triggered, and the
+ * - value of recive_sig does not equal the value of signo.
+ *
+ * - [rt_signal_kill_test]: Case7(the for Loop) is the same as the loop in [rt_signal_mask_test].
+ * - Case9 Verifies that when an invalid signal is sent using rt_signal_kill, the function returns
+ * - -RT_EINVAL.
+ *
+ * - [rt_signal_wait_test]: In this test case, a new thread("sig_t1") is created to execute the
+ * - rt_signal_wait_thread function. Inside the new thread, the SIGUSR1 signal handler is
+ * - installed and unmasked. The thread then waits for the SIGUSR1 signal with a timeout of
+ * - RT_TICK_PER_SECOND ticks. Meanwhile, the main test case thread sleeps for 1ms to ensure that
+ * - "sig_t1" is waiting for the signal, and then sends the SIGUSR1 signal to "sig_t1" using
+ * - rt_thread_kill. The main thread then waits on the _received_signal semaphore, which will be
+ * - released by "sig_t1" upon receiving the signal. Finally, the test case verifies that the
+ * - recive_sig variable is set to SIGUSR1, confirming that the signal was successfully
+ * - received by the waiting thread.
+ *
+ * - [rt_signal_wait_test2]: Similar to [rt_signal_wait_test], a new thread("sig_t1") is created
+ * - to execute the rt_signal_wait_thread function. But in this case, after creating the thread,
+ * - the main test case thread sleeps for 2000ms, which is longer than the 1-second timeout
+ * - specified in rt_signal_wait_thread. After waking up, the main thread sends the SIGUSR1 signal
+ * - to "sig_t1" using rt_thread_kill. Since "sig_t1" has already timed out waiting for the signal,
+ * - it will not receive the signal. The main thread then attempts to take the _received_signal
+ * - semaphore with a timeout of 1 tick, which should fail since "sig_t1" did not receive the signal
+ * - and thus did not release the semaphore. Finally, the test case verifieds that the receive_sig
+ * - variable is not equal to SIGUSR1, confirming that the signal was not received by the waiting thread
+ * - due to the timeout.
+ *
+ * Verification Metrics:
+ *
+ * - [rt_signal_install_test]: Case 1 (i.e., the rt_signal_install inside the for loop)
+ * - will not return SIG_ERR. Case 2 (i.e., the rt_signal_install outside the for loop)
+ * - will return SIG_ERR.
+ *
+ * - [rt_signal_mask_test]: Every signo shall correctly trigger the signal handler, such
+ * - that recive_sig equals signo.
+ *
+ * - [rt_signal_unmask_test]: Every signo shall not trigger the signal handler after masking,
+ * - such that recive_sig does not equal signo.
+ *
+ * - [rt_signal_kill_test]: In Case7, every signo shall correctly trigger the signal handler,
+ * - such that recive_sig equals signo. In Case9, rt_signal_kill shall return -RT_EINVAL.
+ *
+ * - [rt_signal_wait_test]: In Case5, recive_sig shall equal SIGUSR1, indicating that the waiting
+ * - thread successfully received the signal. And main thread can take the semaphore.
+ *
+ * - [rt_signal_wait_test2]: In Case6, recive_sig shall not equal SIGUSR1, indicating that the waiting
+ * - thread did not receive the signal due to timeout. And main thread fails to take the semaphore.
+ *
+ * Dependencies:
+ * - Case1-9: Enable RT_USING_SIGNALS and RT_USING_HEAP.
+ *
+ * Expected Results:
+ * - [rt_signal_install_test]: Handlers installed successfully for all valid signals,
+ * - installation fails for invalid signal.
+ *
+ * - [rt_signal_mask_test]: Signals are received when unmasked.
+ *
+ * - [rt_signal_unmask_test]: Signals are not received when masked.
+ *
+ * - [rt_signal_kill_test]: Signals are sent and received correctly for valid cases,
+ * - errors returned for invalid cases.
+ *
+ * - [rt_signal_wait_test]: Signals are correctly received by waiting threads and semaphore
+ * - is released as expected.
+ *
+ * - [rt_signal_wait_test2]: Signals are not received after timeout and semaphore take fails.
  */
 
 #include <rtthread.h>