Fix #1930, add code coverage for null check

Fix #1930, add code coverage for null check in es.
Add CFE_ES_GenPoolCreatePoolBlock and CFE_ES_GenPoolRecyclePoolBlock to
header file

modules/es/fsw/src/cfe_es_generic_pool.h

@@ -158,6 +158,39 @@ int32 CFE_ES_GenPoolInitialize(CFE_ES_GenPoolRecord_t *PoolRecPtr, size_t StartO
  */
 int32 CFE_ES_GenPoolGetBlock(CFE_ES_GenPoolRecord_t *PoolRecPtr, size_t *BlockOffsetPtr, size_t ReqSize);
 
+/*---------------------------------------------------------------------------------------*/
+/**
+ * \brief Create a new block of the given size.
+ *
+ * \note Internal helper routine only, not part of API.
+ *
+ * \param[inout] PoolRecPtr      Pointer to pool structure
+ * \param[in]    BucketId        Bucket ID
+ * \param[in]    NewSize         Size of block
+ * \param[out]   BlockOffsetPtr  Location to output new block offset 
+ *
+ * \return #CFE_SUCCESS, or error code #CFE_ES_BUFFER_NOT_IN_POOL #CFE_ES_ERR_MEM_BLOCK_SIZE
+ *         \ref CFEReturnCodes
+ */
+int32 CFE_ES_GenPoolCreatePoolBlock(CFE_ES_GenPoolRecord_t *PoolRecPtr, uint16 BucketId, size_t NewSize, 
+                                    size_t *BlockOffsetPtr);
+
+/*---------------------------------------------------------------------------------------*/
+/**
+ * \brief Find and re-allocate a previously returned block
+ *
+ * \note Internal helper routine only, not part of API.
+ *
+ * \param[inout] PoolRecPtr      Pointer to pool structure
+ * \param[in]    BucketId        Bucket ID
+ * \param[in]    NewSize         Size of block
+ * \param[out]   BlockOffsetPtr  Location to output new block offset 
+ *
+ * \return #CFE_SUCCESS, or error code #CFE_ES_BUFFER_NOT_IN_POOL \ref CFEReturnCodes
+ */
+int32 CFE_ES_GenPoolRecyclePoolBlock(CFE_ES_GenPoolRecord_t *PoolRecPtr, uint16 BucketId, size_t NewSize,
+                                     size_t *BlockOffsetPtr);
+
 /*---------------------------------------------------------------------------------------*/
 /**
  * \brief Returns a block to the pool

modules/es/ut-coverage/es_UT.c

@@ -2457,6 +2457,16 @@ void TestGenericPool(void)
     /* Reset the structure so it will rebuild */
     Pool1.TailPosition = 0;
     CFE_UtAssert_SUCCESS(CFE_ES_GenPoolRebuild(&Pool1));
+
+    /* Branch coverage for no buffer in pool */
+    ES_ResetUnitTest();
+    UtAssert_INT32_EQ(CFE_ES_GenPoolCreatePoolBlock(&Pool1, 0, Pool1.Buckets[0].BlockSize, &Offset1),
+                      CFE_ES_BUFFER_NOT_IN_POOL);
+
+    ES_ResetUnitTest();
+    UtAssert_INT32_EQ(CFE_ES_GenPoolRecyclePoolBlock(&Pool1, 0, Pool1.Buckets[0].BlockSize, &Offset1),
+                      CFE_ES_BUFFER_NOT_IN_POOL);
+
 }
 
 void TestTask(void)