tests/thread_float: improve output and add test script

- Give the three threads the names "t1", "t2", and "t3" and print them
  on console, instead of the process ID. This makes interpretation of
  the output easier, as the process IDs depend e.g. on whether a given
  platforms requires an idle thread or not.
- Do not use the thread ID in the calculation, but the number at the
  end of the thread name. This will result in the number printed only
  depending on the precision of the (software) FPU and the printf()
  implementation, and not on which threads are created in which order
  (including the idle thread)
- Add a script to support running `make test`

tests/thread_float/main.c

@@ -19,6 +19,7 @@
  */
 
 #include <stdio.h>
+#include <string.h>
 
 #include "thread.h"
 #include "msg.h"
@@ -44,39 +45,43 @@ static void timer_cb(void *arg)
     xtimer_set(&timer, OFFSET);
 }
 
-static void *thread1(void *arg)
+static void *thread1(void *_arg)
 {
-    (void) arg;
-
+    const char *arg = _arg;
     float f, init;
 
-    printf("THREAD %" PRIkernel_pid " start\n", thread_getpid());
+    mutex_lock(&lock);
+    printf("THREAD %s start\n", arg);
+    mutex_unlock(&lock);
 
-    init = 1.0 * thread_getpid();
+    /* Use number at end of thread name, e.g. 3 for "t3", to seed the calculation */
+    init = 1.0 * (arg[strlen(arg) - 1] - '0');
     f = init;
 
     while (1) {
         for (unsigned long i = 0; i < 10000ul; i++) {
             f = f + 1.0 / f;
         }
         mutex_lock(&lock);
-        printf("T(%" PRIkernel_pid "): %f\n", thread_getpid(), (double)f);
+        printf("%s: %f\n", arg, (double)f);
         mutex_unlock(&lock);
         init += 1.0;
         f = init;
     }
     return NULL;
 }
 
-static void *thread2(void *arg)
+static void *thread2(void *_arg)
 {
-    (void) arg;
-
+    const char *arg = _arg;
     float f, init;
 
-    printf("THREAD %" PRIkernel_pid " start\n", thread_getpid());
+    mutex_lock(&lock);
+    printf("THREAD %s start\n", arg);
+    mutex_unlock(&lock);
 
-    init = 1.0 * thread_getpid();
+    /* Use number at end of thread name, e.g. 3 for "t3", to seed the calculation */
+    init = 1.0 * (arg[strlen(arg) - 1] - '0');
     f = init;
 
     while (1) {
@@ -91,15 +96,18 @@ static void *thread2(void *arg)
 
 int main(void)
 {
+    const char *t1_name = "t1";
+    const char *t2_name = "t2";
+    const char *t3_name = "t3";
     p1 = thread_create(t1_stack, sizeof(t1_stack), THREAD_PRIORITY_MAIN + 1,
                        THREAD_CREATE_WOUT_YIELD | THREAD_CREATE_STACKTEST,
-                       thread1, NULL, "nr1");
+                       thread1, (void *)t1_name, t1_name);
     p2 = thread_create(t2_stack, sizeof(t2_stack), THREAD_PRIORITY_MAIN + 1,
                        THREAD_CREATE_WOUT_YIELD | THREAD_CREATE_STACKTEST,
-                       thread2, NULL, "nr2");
+                       thread2, (void *)t2_name, t2_name);
     p3 = thread_create(t3_stack, sizeof(t3_stack), THREAD_PRIORITY_MAIN + 1,
                        THREAD_CREATE_WOUT_YIELD | THREAD_CREATE_STACKTEST,
-                       thread1, NULL, "nr3");
+                       thread1, (void *)t3_name, t3_name);
     puts("THREADS CREATED\n");
 
     timer.callback = timer_cb;

tests/thread_float/tests/01-run.py

@@ -0,0 +1,34 @@
+#!/usr/bin/env python3
+
+#  Copyright (C) 2021 Otto-von-Guericke-Universität Magdeburg
+#
+# This file is subject to the terms and conditions of the GNU Lesser
+# General Public License v2.1. See the file LICENSE in the top level
+# directory for more details.
+
+# @author      Marian Buschsieweke <marian.buschsieweke@ovgu.de>
+
+import sys
+from testrunner import run
+
+
+def testfunc(child):
+    child.expect("THREADS CREATED")
+    child.expect("")
+    child.expect("THREAD t1 start")
+    child.expect("THREAD t2 start")
+    child.expect("THREAD t3 start")
+    for _ in range(10):
+        child.expect(r"t(\d): (\d\d\d).\d+")
+        first_thread = int(child.match.group(1))
+        assert 141 == int(child.match.group(2))
+        assert (first_thread == 1) or (first_thread == 3)
+        child.expect(r"t(\d): (\d\d\d).\d+")
+        second_thread = int(child.match.group(1))
+        assert 141 == int(child.match.group(2))
+        assert (second_thread == 1) or (second_thread == 3)
+        assert first_thread != second_thread
+
+
+if __name__ == "__main__":
+    sys.exit(run(testfunc))