From d34d35de172d9f1fb961b180b5d76fbffdc1a104 Mon Sep 17 00:00:00 2001
From: "Knutsen, Daniel M 987600011" <daniel.m.knutsen@nasa.gov>
Date: Tue, 23 Jul 2024 21:59:57 +0000
Subject: [PATCH] Fix #100, Check CFE_SB_NO_MESSAGE return code

Fix #100, check cfe_sb_no_message return code from CFE_SB_ReceiveBuffer
---
 fsw/src/mm_app.c         |  2 +-
 unit-test/mm_app_tests.c | 35 +++++++++++++++++++++++++++++++++++
 2 files changed, 36 insertions(+), 1 deletion(-)

diff --git a/fsw/src/mm_app.c b/fsw/src/mm_app.c
index afc573d..80ce42e 100644
--- a/fsw/src/mm_app.c
+++ b/fsw/src/mm_app.c
@@ -91,7 +91,7 @@ void MM_AppMain(void) {
     if ((Status == CFE_SUCCESS) && (BufPtr != NULL)) {
       /* Process Software Bus message */
       MM_TaskPipe(BufPtr);
-    } else if (Status == CFE_SB_TIME_OUT) {
+    } else if (Status == CFE_SB_TIME_OUT || Status == CFE_SB_NO_MESSAGE) {
       /* No action, but also no error */
     } else {
       /*
diff --git a/unit-test/mm_app_tests.c b/unit-test/mm_app_tests.c
index 1f28abe..a4c5afc 100644
--- a/unit-test/mm_app_tests.c
+++ b/unit-test/mm_app_tests.c
@@ -47,6 +47,14 @@
 /* Function Definitions */
 /* ==================== */
 
+int32 MM_APP_TEST_CFE_ES_ExitAppHook(void *UserObj, int32 StubRetcode, uint32 CallCount,
+                                     const UT_StubContext_t *Context)
+{
+    MM_AppData.HkTlm.Payload.CmdCounter++;
+
+    return 0;
+}
+
 void MM_AppMain_Test_Nominal(void) {
   CFE_SB_Buffer_t Buf;
   CFE_SB_Buffer_t *BufPtr = &Buf;
@@ -121,6 +129,32 @@ void MM_AppMain_Test_SBTimeout(void) {
   UtAssert_STUB_COUNT(CFE_EVS_SendEvent, 1);
 }
 
+void MM_AppMain_Test_SBNoMessage(void)
+{
+    size_t         forced_Size  = 1;
+    CFE_SB_MsgId_t forced_MsgID = MM_UT_MID_1;
+
+    /* Set to exit loop after first run */
+    UT_SetDeferredRetcode(UT_KEY(CFE_ES_RunLoop), 1, true);
+
+    /* Set to generate error message CFE_SB_NO_MESSAGE */
+    UT_SetDefaultReturnValue(UT_KEY(CFE_SB_ReceiveBuffer), CFE_SB_NO_MESSAGE);
+
+    /* Set to prevent segmentation fault */
+    UT_SetDataBuffer(UT_KEY(CFE_MSG_GetMsgId), &forced_MsgID, sizeof(forced_MsgID), false);
+    UT_SetDataBuffer(UT_KEY(CFE_MSG_GetSize), &forced_Size, sizeof(forced_Size), false);
+
+    /* Used to verify completion of MM_AppMain by incrementing MM_AppData.HkPacket.CmdCounter. */
+    UT_SetHookFunction(UT_KEY(CFE_ES_ExitApp), MM_APP_TEST_CFE_ES_ExitAppHook, NULL);
+
+    /* Execute the function being tested */
+    UtAssert_VOIDCALL(MM_AppMain());
+
+    /* Verify results */
+    /* Generates 1 event message we don't care about in this test */
+    UtAssert_STUB_COUNT(CFE_EVS_SendEvent, 1);
+}
+
 void MM_AppInit_Test_Nominal(void) {
   CFE_Status_t Result;
 
@@ -271,6 +305,7 @@ void UtTest_Setup(void) {
   ADD_TEST(MM_AppMain_Test_AppInitError);
   ADD_TEST(MM_AppMain_Test_SBError);
   ADD_TEST(MM_AppMain_Test_SBTimeout);
+  ADD_TEST(MM_AppMain_Test_SBNoMessage);
   ADD_TEST(MM_AppInit_Test_Nominal);
   ADD_TEST(MM_AppInit_Test_EVSRegisterError);
   ADD_TEST(MM_AppInit_Test_SBCreatePipeError);