tests: kernel: mem_heap: Add CONFIG_MULTITHREADING=n configuration

Extended mheap_api_concept test suite to support case when
multithreading is disabled.

Signed-off-by: Krzysztof Chruscinski <krzysztof.chruscinski@nordicsemi.no>

tests/kernel/mem_heap/mheap_api_concept/prj.conf

@@ -1,3 +1,2 @@
 CONFIG_ZTEST=y
 CONFIG_HEAP_MEM_POOL_SIZE=256
-CONFIG_IRQ_OFFLOAD=y

tests/kernel/mem_heap/mheap_api_concept/src/test_mheap_api.c

@@ -176,6 +176,10 @@ void test_k_aligned_alloc(void)
  */
 void test_sys_heap_mem_pool_assign(void)
 {
+	if (!IS_ENABLED(CONFIG_MULTITHREADING)) {
+		return;
+	}
+
 	void *ptr;
 
 	k_thread_system_pool_assign(k_current_get());
@@ -201,6 +205,10 @@ void test_sys_heap_mem_pool_assign(void)
  */
 void test_malloc_in_isr(void)
 {
+	if (!IS_ENABLED(CONFIG_IRQ_OFFLOAD)) {
+		return;
+	}
+
 	irq_offload((irq_offload_routine_t)tIsr_malloc_and_free, NULL);
 }
 
@@ -216,6 +224,10 @@ void test_malloc_in_isr(void)
  */
 void test_malloc_in_thread(void)
 {
+	if (!IS_ENABLED(CONFIG_MULTITHREADING)) {
+		return;
+	}
+
 	k_tid_t tid = k_thread_create(&tdata, tstack, STACK_SIZE,
 			      thread_entry, NULL, NULL, NULL,
 			      0, 0, K_NO_WAIT);

tests/kernel/mem_heap/mheap_api_concept/src/test_mheap_concept.c

@@ -75,6 +75,10 @@ static void tmheap_handler(void *p1, void *p2, void *p3)
  */
 void test_mheap_threadsafe(void)
 {
+	if (!IS_ENABLED(CONFIG_MULTITHREADING)) {
+		return;
+	}
+
 	k_tid_t tid[THREAD_NUM];
 
 	k_sem_init(&sync_sema, 0, THREAD_NUM);

tests/kernel/mem_heap/mheap_api_concept/testcase.yaml

@@ -1,3 +1,10 @@
 tests:
   kernel.memory_heap:
     tags: kernel
+    extra_configs:
+      - CONFIG_IRQ_OFFLOAD=y
+  kernel.memory_heap_no_multithreading:
+    tags: kernel
+    platform_allow: qemu_cortex_m3 qemu_cortex_m0
+    extra_configs:
+      - CONFIG_MULTITHREADING=n