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diff --git a/usth/ICT2.7/P4L3 White-Box Testing Subtitles/22 - MC DC Coverage - lang_en_vs4.srt b/usth/ICT2.7/P4L3 White-Box Testing Subtitles/22 - MC DC Coverage - lang_en_vs4.srt deleted file mode 100644 index 1a971f9..0000000 --- a/usth/ICT2.7/P4L3 White-Box Testing Subtitles/22 - MC DC Coverage - lang_en_vs4.srt +++ /dev/null @@ -1,307 +0,0 @@ -1 -00:00:00,120 --> 00:00:03,880 -And this criterion is called Modified Condition/Decision Coverage, - -2 -00:00:03,880 --> 00:00:07,750 -also called MC/DC. This criterion is very important because - -3 -00:00:07,750 --> 00:00:10,330 -it is often required for safety critical applications. - -4 -00:00:10,330 --> 00:00:13,920 -For example, the FAA, the Federal Aviation Administration, requires - -5 -00:00:13,920 --> 00:00:15,980 -for all the software that runs on commercial - -6 -00:00:15,980 --> 00:00:19,420 -airplanes to be tested according to the Modified Condition/Decision - -7 -00:00:19,420 --> 00:00:22,015 -Coverage. So what is the key idea behind the - -8 -00:00:22,015 --> 00:00:25,270 -MC/DC criterion? It is to test only the important - -9 -00:00:25,270 --> 00:00:28,710 -combinations of conditions instead of all of them, and limit - -10 -00:00:28,710 --> 00:00:32,189 -the testing cost by excluding the other combinations. And the way - -11 -00:00:32,189 --> 00:00:34,950 -in which it works is by extending branch and decision - -12 -00:00:34,950 --> 00:00:38,860 -coverage with the requirement that each condition should affect the decision - -13 -00:00:38,860 --> 00:00:41,940 -outcome independently. So let's see what this means with an - -14 -00:00:41,940 --> 00:00:45,030 -example that will also show you how you can reduce the - -15 -00:00:45,030 --> 00:00:46,940 -number of combinations in this way. I am going to - -16 -00:00:46,940 --> 00:00:50,460 -show you an example of how MC/DC works using this predicate - -17 -00:00:50,460 --> 00:00:53,870 -which consists of three conditions. a, b, and c, which are all - -18 -00:00:53,870 --> 00:00:57,070 -in and, so the overall predicate is a and b and c. - -19 -00:00:57,070 --> 00:00:58,980 -The first thing I'm going to do is to show you how - -20 -00:00:58,980 --> 00:01:03,370 -many test cases we will need to satisfy the multiple condition coverage - -21 -00:01:03,370 --> 00:01:06,440 -for this simple predicate. Which means, how many test cases we will - -22 -00:01:06,440 --> 00:01:09,780 -need to test all the possible combinations of true and false values - -23 -00:01:09,780 --> 00:01:12,740 -for these conditions. So I'm going to populate this table. And as you - -24 -00:01:12,740 --> 00:01:15,870 -can see, at the end we have eight test cases. Each test case - -25 -00:01:15,870 --> 00:01:18,650 -tests a different combination of values for a, b, and c. - -26 -00:01:18,650 --> 00:01:21,200 -I'm also showing, for each test case, the outcome of the overall - -27 -00:01:21,200 --> 00:01:23,930 -predicate. So, for example, if we look at the first one, the - -28 -00:01:23,930 --> 00:01:27,200 -first test case, will be such that a is true, b is - -29 -00:01:27,200 --> 00:01:30,210 -true, and c is true. And therefore, the overall outcome of - -30 -00:01:30,210 --> 00:01:34,360 -the predicate is true. Now lets consider the first condition, a. As - -31 -00:01:34,360 --> 00:01:36,300 -I said a minute ago, what we want to test are the - -32 -00:01:36,300 --> 00:01:39,160 -important combination. Which are the comibatinos - -33 -00:01:39,160 --> 00:01:41,930 -in which a single condition independently - -34 -00:01:41,930 --> 00:01:45,610 -effects the outcome of the overall predicate. So if we consider a - -35 -00:01:45,610 --> 00:01:48,490 -and we look at this possible set of this cases. Let's try to - -36 -00:01:48,490 --> 00:01:51,850 -find two test cases such that the only difference between the two - -37 -00:01:51,850 --> 00:01:54,960 -test cases is the value of a, and the overall outcome of the - -38 -00:01:54,960 --> 00:01:57,790 -predicate is different. If we look at the table, we can see - -39 -00:01:57,790 --> 00:02:00,920 -that this is true for test cases one and five. If we look - -40 -00:02:00,920 --> 00:02:04,030 -at these two cases, we can see that the overall of the predicate - -41 -00:02:04,030 --> 00:02:07,420 -in the two cases is true and false, and that the only difference - -42 -00:02:07,420 --> 00:02:10,720 -between the value of the conditions in the value of a. So - -43 -00:02:10,720 --> 00:02:13,990 -these test cases satisfy exactly what we wanted. There are two test - -44 -00:02:13,990 --> 00:02:18,270 -cases in which the value of a independently decides the overall value - -45 -00:02:18,270 --> 00:02:21,380 -of the predicate. What we do, therefore, is to add these first - -46 -00:02:21,380 --> 00:02:24,740 -two test cases to our set of tests down here. Now let's - -47 -00:02:24,740 --> 00:02:27,520 -focus on b and let's try to find two test cases such - -48 -00:02:27,520 --> 00:02:30,280 -that the value of b is the only value that changes between - -49 -00:02:30,280 --> 00:02:32,450 -the two test cases, but the overall value of the predicate is - -50 -00:02:32,450 --> 00:02:34,980 -different, the same thing we did for a. And in this case, - -51 -00:02:34,980 --> 00:02:37,610 -we can see that if we select test case number one, and test - -52 -00:02:37,610 --> 00:02:40,420 -case number three, we have exactly that situation. b is true in the - -53 -00:02:40,420 --> 00:02:44,250 -first case, false in the second one, a and c don't change, but - -54 -00:02:44,250 --> 00:02:46,830 -the overall value of the predicate changes. And now you can notice - -55 -00:02:46,830 --> 00:02:50,720 -something else. That even though we selected two test cases, tested two values, - -56 -00:02:50,720 --> 00:02:53,950 -one we already had. So, we only need three test cases overall to - -57 -00:02:53,950 --> 00:02:57,730 -test a and b according to MC/DC. Now, let's look at our last - -58 -00:02:57,730 --> 00:03:00,510 -condition, c. At this point, we know the game, so we - -59 -00:03:00,510 --> 00:03:02,780 -just have to look for two test cases that satisfy our - -60 -00:03:02,780 --> 00:03:06,380 -requirements. And in this case, one and two are suitable candidates. - -61 -00:03:06,380 --> 00:03:08,820 -And once more, because we already have one, we just have to - -62 -00:03:08,820 --> 00:03:11,070 -add two to our list. So as you can see from - -63 -00:03:11,070 --> 00:03:14,730 -this example, we went from having eight test cases needed to cover - -64 -00:03:14,730 --> 00:03:18,600 -all the possible combinations of conditions to only four test cases - -65 -00:03:18,600 --> 00:03:22,880 -to satisfy the MC/DC criteria. So let's see where MC/DC stands in - -66 -00:03:22,880 --> 00:03:25,510 -our substantion hierarchy. This is what we had so far - -67 -00:03:25,510 --> 00:03:28,430 -in the hierarchy and this is where the MC/DC criterion will - -68 -00:03:28,430 --> 00:03:31,930 -stand. MC/DC criterion is stronger than branch and condition coverage. - -69 -00:03:31,930 --> 00:03:35,210 -Why? Because it requires every single condition to be true and - -70 -00:03:35,210 --> 00:03:38,400 -false. And therefore, this section was a condition coverage criteria. - -71 -00:03:38,400 --> 00:03:41,610 -And it also requires every predicate to be true and false - -72 -00:03:41,610 --> 00:03:44,425 -and therefore, this section is branch coverage. And in addition, - -73 -00:03:44,425 --> 00:03:47,790 -it's got the additional requirements that the true and false values, - -74 -00:03:47,790 --> 00:03:50,330 -all the conditions have to also decide the overall - -75 -00:03:50,330 --> 00:03:53,190 -value of the predicate. So it's stronger. Which is more - -76 -00:03:53,190 --> 00:03:56,130 -thorough than branch and condition coverage and, as usual, - -77 -00:03:56,130 --> 00:03:59,380 -also stronger than branch coverage, statement coverage, and condition coverage. |