fix "promise: Support threshold-days in check_free_disk_space"

There was mistake, as result_max[0] is already free disk space, so there
was no need to do 1. - result_max[0]. Unfortunately tests were also
incorrectly adjusted.

slapos/promise/plugin/check_free_disk_space.py

@@ -59,7 +59,7 @@ is assumed constant and used to predict in how many days the disk would become f
         result_min[1], timep)
       delta_days = timespan.total_seconds() / (3600.*24)
       try:
-        return (-(1. - result_max[0]) / (change / delta_days), result_min[1], result_min[0], result_max[1], result_max[0], delta_days)
+        return (-result_max[0] / (change / delta_days), result_min[1], result_min[0], result_max[1], result_max[0], delta_days)
       except ZeroDivisionError as e:
         # no data
         return None

slapos/test/promise/data/disktest.sql

 BEGIN TRANSACTION;
 CREATE TABLE disk (partition text, used text, free text, mountpoint text,  date text, time text, reported integer NULL DEFAULT 0);
-INSERT INTO "disk" VALUES('/dev/sda1','157210666368','290958396032','/','2017-10-02','01:16:01',1);
+INSERT INTO "disk" VALUES('/dev/sda1','155510666368','292658396032','/','2017-10-02','01:16:01',1);
 INSERT INTO "disk" VALUES('/dev/sda1','159220666368','288948396032','/','2017-10-02','09:17:01',1);
 INSERT INTO "disk" VALUES('/dev/sda1','159237537792','288931524608','/','2017-10-02','09:18:01',1);
 INSERT INTO "disk" VALUES('/dev/sda1','159238090752','288930971648','/','2017-10-02','09:19:02',1);

slapos/test/promise/plugin/test_check_free_disk_space.py

@@ -88,7 +88,7 @@ extra_config_dict = {
     result = self.getPromiseResult(self.promise_name)
     self.assertEqual(result['result']['failed'], False)
     self.assertEqual(result['result']['message'],
-      "Disk will become full in 26.46 days (threshold: 25.00 days), checked from 2017-10-02 01:16:01 to 2017-10-02 09:17:01, 0.33 days span: OK\nDisk usage: OK")
+      "Disk will become full in 26.02 days (threshold: 25.00 days), checked from 2017-10-02 01:16:01 to 2017-10-02 09:17:01, 0.33 days span: OK\nDisk usage: OK")
 
   def test_disk_space_ok_will_full_soon(self):
     content = """from slapos.promise.plugin.check_free_disk_space import RunPromise
@@ -106,7 +106,7 @@ extra_config_dict = {
     self.assertEqual(result['result']['failed'], True)
     self.assertEqual(
       result['result']['message'],
-      "Disk will become full in 26.46 days (threshold: 30.00 days), checked from 2017-10-02 01:16:01 to 2017-10-02 09:17:01, 0.33 days span, free space dropped from 64.9% to 64.5%: ERROR\nDisk usage: OK")
+      "Disk will become full in 26.02 days (threshold: 30.00 days), checked from 2017-10-02 01:16:01 to 2017-10-02 09:17:01, 0.33 days span, free space dropped from 65.3% to 64.5%: ERROR\nDisk usage: OK")
 
   def test_disk_space_nok(self):
     content = """from slapos.promise.plugin.check_free_disk_space import RunPromise
@@ -126,7 +126,7 @@ extra_config_dict = {
     result = self.getPromiseResult(self.promise_name)
     self.assertEqual(result['result']['failed'], True)
     self.assertEqual(result['result']['message'],
-      "Disk will become full in 26.46 days (threshold: 25.00 days), checked from 2017-10-02 01:16:01 to 2017-10-02 09:17:01, 0.33 days span: OK\nFree disk space low: remaining 269.1 G (threshold: 278.0 G)")
+      "Disk will become full in 26.02 days (threshold: 25.00 days), checked from 2017-10-02 01:16:01 to 2017-10-02 09:17:01, 0.33 days span: OK\nFree disk space low: remaining 269.1 G (threshold: 278.0 G)")
 
   def test_disk_space_nok_will_full_soon(self):
     content = """from slapos.promise.plugin.check_free_disk_space import RunPromise
@@ -145,7 +145,7 @@ extra_config_dict = {
     result = self.getPromiseResult(self.promise_name)
     self.assertEqual(result['result']['failed'], True)
     self.assertEqual(result['result']['message'],
-      "Disk will become full in 26.46 days (threshold: 30.00 days), checked from 2017-10-02 01:16:01 to 2017-10-02 09:17:01, 0.33 days span, free space dropped from 64.9% to 64.5%: ERROR\nFree disk space low: remaining 269.1 G (threshold: 278.0 G)")
+      "Disk will become full in 26.02 days (threshold: 30.00 days), checked from 2017-10-02 01:16:01 to 2017-10-02 09:17:01, 0.33 days span, free space dropped from 65.3% to 64.5%: ERROR\nFree disk space low: remaining 269.1 G (threshold: 278.0 G)")
 
   def test_check_free_disk_with_unicode_string_path(self):
     # set path unicode
@@ -154,7 +154,7 @@ extra_config_dict = {
     self.launcher.run()
     result = self.getPromiseResult(self.promise_name)
     self.assertEqual(result['result']['failed'], False)
-    self.assertEqual(result['result']['message'], "Disk will become full in 26.46 days (threshold: 25.00 days), checked from 2017-10-02 01:16:01 to 2017-10-02 09:17:01, 0.33 days span: OK\nDisk usage: OK")
+    self.assertEqual(result['result']['message'], "Disk will become full in 26.02 days (threshold: 25.00 days), checked from 2017-10-02 01:16:01 to 2017-10-02 09:17:01, 0.33 days span: OK\nDisk usage: OK")
 
 if __name__ == '__main__':
   unittest.main()