1
00:00:00,480 --> 00:00:03,480
foreign

2
00:00:10,099 --> 00:00:15,680
it's my pleasure to introduce Peter from

3
00:00:13,440 --> 00:00:19,380
the Australian energy Market operator

4
00:00:15,680 --> 00:00:23,779
with 6qa tall QA tools that'll make your

5
00:00:19,380 --> 00:00:23,779
python code better take it away Peter

6
00:00:24,720 --> 00:00:27,619
thank you and welcome

7
00:00:27,720 --> 00:00:31,980
who's this talk for

8
00:00:29,880 --> 00:00:34,739
the Amo team in this case study right

9
00:00:31,980 --> 00:00:36,960
critical Enterprise code that executes

10
00:00:34,739 --> 00:00:41,340
on a lock lockdown serves in the cool

11
00:00:36,960 --> 00:00:43,620
room we are very very conservative

12
00:00:41,340 --> 00:00:47,040
I'll be advocating you spend about 45

13
00:00:43,620 --> 00:00:49,500
percent of your Dev Budget on code QA

14
00:00:47,040 --> 00:00:51,420
this may not be for you but we'll

15
00:00:49,500 --> 00:00:54,539
proceed anyway

16
00:00:51,420 --> 00:00:56,340
before I start I have a question and the

17
00:00:54,539 --> 00:00:59,399
question is a question

18
00:00:56,340 --> 00:01:01,680
what is the hardest question for a coder

19
00:00:59,399 --> 00:01:03,899
to answer

20
00:01:01,680 --> 00:01:05,880
give some thought to that although

21
00:01:03,899 --> 00:01:09,860
scroll through the next few slides and

22
00:01:05,880 --> 00:01:09,860
we'll talk about that more in a moment

23
00:01:10,080 --> 00:01:14,280
first of all can you spot the bug in

24
00:01:12,180 --> 00:01:16,020
this code

25
00:01:14,280 --> 00:01:18,299
probably not a fair question because you

26
00:01:16,020 --> 00:01:21,540
haven't seen the context but you can see

27
00:01:18,299 --> 00:01:25,100
that it opens a text file it

28
00:01:21,540 --> 00:01:28,500
iterates over it it pulls out gosh

29
00:01:25,100 --> 00:01:30,540
column number six it adds the value to a

30
00:01:28,500 --> 00:01:32,820
list it sorts it and it prints it out

31
00:01:30,540 --> 00:01:36,240
what's the whole point of that well

32
00:01:32,820 --> 00:01:38,939
here's the underlying data this is a

33
00:01:36,240 --> 00:01:40,920
typical Market data that we deal with at

34
00:01:38,939 --> 00:01:44,640
work it's available on the public

35
00:01:40,920 --> 00:01:47,460
internet and it shows the generation in

36
00:01:44,640 --> 00:01:50,040
megawatts against each generator in the

37
00:01:47,460 --> 00:01:51,899
nem at a point in time the point in time

38
00:01:50,040 --> 00:01:55,259
we do this every five minutes

39
00:01:51,899 --> 00:01:58,380
The Columns of Interest are f

40
00:01:55,259 --> 00:02:01,200
a value we call do it or dispatch unit

41
00:01:58,380 --> 00:02:05,579
ID we call a generator A dispatch unit

42
00:02:01,200 --> 00:02:07,560
and column G scada value which is the

43
00:02:05,579 --> 00:02:09,239
megawatts of that unit is producing at

44
00:02:07,560 --> 00:02:11,520
that point in time

45
00:02:09,239 --> 00:02:14,160
you can often reverse engineer where the

46
00:02:11,520 --> 00:02:16,400
unit is in the country by looking at the

47
00:02:14,160 --> 00:02:16,400
name

48
00:02:16,459 --> 00:02:22,379
c-a-p-t-l underscore WF for example on

49
00:02:19,800 --> 00:02:25,200
row whatever it is six is Capitol Hill

50
00:02:22,379 --> 00:02:27,300
Wind Farm outside Canberra

51
00:02:25,200 --> 00:02:30,200
eyeballing the data you can see the

52
00:02:27,300 --> 00:02:33,360
lowest value is around about negative

53
00:02:30,200 --> 00:02:35,819
0.02 and the highest value is around

54
00:02:33,360 --> 00:02:37,440
about 620

55
00:02:35,819 --> 00:02:39,599
back to our code

56
00:02:37,440 --> 00:02:42,000
it opens the file

57
00:02:39,599 --> 00:02:44,400
it iterates that it pulls out column six

58
00:02:42,000 --> 00:02:46,019
it adds it to It List It sorts it and it

59
00:02:44,400 --> 00:02:47,879
prints out what we think going to be the

60
00:02:46,019 --> 00:02:49,500
first value and the last value the

61
00:02:47,879 --> 00:02:52,620
minimum megawatts and the maximum

62
00:02:49,500 --> 00:02:54,739
megawatts and we get this

63
00:02:52,620 --> 00:02:58,379
minus

64
00:02:54,739 --> 00:03:00,120
0.0015 and 97.

65
00:02:58,379 --> 00:03:02,580
the answer's wrong

66
00:03:00,120 --> 00:03:04,379
so where's the bug

67
00:03:02,580 --> 00:03:06,120
this is perhaps the worst sort of bug

68
00:03:04,379 --> 00:03:07,739
you can get because it executes it

69
00:03:06,120 --> 00:03:09,900
produces a number but the number's

70
00:03:07,739 --> 00:03:12,420
absolute nonsense

71
00:03:09,900 --> 00:03:16,819
so what we need is a crutch to lean on

72
00:03:12,420 --> 00:03:16,819
to help us not make this error

73
00:03:17,840 --> 00:03:24,780
let's get a bit smart now we'll

74
00:03:20,519 --> 00:03:26,640
introduce a class structure to help us

75
00:03:24,780 --> 00:03:28,620
class structure to lean on or a

76
00:03:26,640 --> 00:03:31,920
different coding style to help us

77
00:03:28,620 --> 00:03:34,739
avoid that error down the track and of

78
00:03:31,920 --> 00:03:37,140
course the error was that we're adding

79
00:03:34,739 --> 00:03:39,060
our numeric values as a string to a list

80
00:03:37,140 --> 00:03:41,099
and sorting is a string and strings are

81
00:03:39,060 --> 00:03:43,019
numbers sort differently so we're

82
00:03:41,099 --> 00:03:44,879
getting the maximum and minimum value

83
00:03:43,019 --> 00:03:45,900
based on the fact that it's a string not

84
00:03:44,879 --> 00:03:48,299
a number

85
00:03:45,900 --> 00:03:49,860
let's inject some code that forces it to

86
00:03:48,299 --> 00:03:53,700
be a number

87
00:03:49,860 --> 00:03:57,060
so I've created a class line eight in

88
00:03:53,700 --> 00:04:00,599
the code called genval it has two

89
00:03:57,060 --> 00:04:03,420
attributes do it and scada value do the

90
00:04:00,599 --> 00:04:07,440
string scalar value is a number it has a

91
00:04:03,420 --> 00:04:09,360
Dunder LT method or a magic python

92
00:04:07,440 --> 00:04:12,659
method that will help us sort this class

93
00:04:09,360 --> 00:04:16,440
where it compares the two scada values

94
00:04:12,659 --> 00:04:19,400
it does a generation line 21 creates an

95
00:04:16,440 --> 00:04:23,699
instance of the class line 22

96
00:04:19,400 --> 00:04:25,320
sets the do it line 23 sets the value it

97
00:04:23,699 --> 00:04:27,060
sets it as a decimal so we're getting

98
00:04:25,320 --> 00:04:31,259
smarter now

99
00:04:27,060 --> 00:04:33,600
it does its sort and it prints the

100
00:04:31,259 --> 00:04:35,759
maximum and minimum value

101
00:04:33,600 --> 00:04:39,259
but it's still wrong

102
00:04:35,759 --> 00:04:43,199
like can you spot the error in this code

103
00:04:39,259 --> 00:04:45,419
again probably not a fair question but

104
00:04:43,199 --> 00:04:47,759
where we work scada value is a value

105
00:04:45,419 --> 00:04:50,220
that's used all over the organization in

106
00:04:47,759 --> 00:04:51,540
many systems and it's it's a word that

107
00:04:50,220 --> 00:04:53,759
we hold in our heads and we probably

108
00:04:51,540 --> 00:04:56,340
translate it without even thinking about

109
00:04:53,759 --> 00:04:59,400
it from one form to the other so line 11

110
00:04:56,340 --> 00:05:01,979
is scada value line

111
00:04:59,400 --> 00:05:04,259
23 where assigning it is scada

112
00:05:01,979 --> 00:05:05,880
underscore value and of course beautiful

113
00:05:04,259 --> 00:05:08,400
infinitely

114
00:05:05,880 --> 00:05:10,139
elastic permissive python will just

115
00:05:08,400 --> 00:05:12,780
swallow that and will create scada

116
00:05:10,139 --> 00:05:16,199
underscore value as an attribute on our

117
00:05:12,780 --> 00:05:18,120
class without complaining

118
00:05:16,199 --> 00:05:20,720
so we need a crutch to prevent us from

119
00:05:18,120 --> 00:05:20,720
that error

120
00:05:21,120 --> 00:05:26,460
more code

121
00:05:23,460 --> 00:05:28,320
Can you spot the area in this code

122
00:05:26,460 --> 00:05:30,900
again these are three areas that I have

123
00:05:28,320 --> 00:05:34,020
made a hundred times and there areas my

124
00:05:30,900 --> 00:05:36,360
team has made a hundred times

125
00:05:34,020 --> 00:05:38,400
the error in this one is a result of

126
00:05:36,360 --> 00:05:42,060
copying and pasting the headers from a

127
00:05:38,400 --> 00:05:44,160
CSV into my code entering some Carriage

128
00:05:42,060 --> 00:05:47,280
returns and then reformatting it so I'm

129
00:05:44,160 --> 00:05:49,860
mapping CSV columns into object

130
00:05:47,280 --> 00:05:52,139
attributes

131
00:05:49,860 --> 00:05:56,400
and invertently left a trailing comma on

132
00:05:52,139 --> 00:05:58,680
line 23. now beautiful permissive python

133
00:05:56,400 --> 00:06:00,960
will just swallow that except it will

134
00:05:58,680 --> 00:06:04,259
set our scada value to be a tuple with

135
00:06:00,960 --> 00:06:05,940
one value in it rather than the actual

136
00:06:04,259 --> 00:06:07,919
value itself

137
00:06:05,940 --> 00:06:10,080
I've changed the context of the code

138
00:06:07,919 --> 00:06:11,880
slightly it's now not looking for the

139
00:06:10,080 --> 00:06:15,300
maximum minimum values but it's trying

140
00:06:11,880 --> 00:06:16,080
to sum the generation available at that

141
00:06:15,300 --> 00:06:19,020
um

142
00:06:16,080 --> 00:06:21,960
uh time period and of course this code

143
00:06:19,020 --> 00:06:25,319
will actually blow up on line 28 because

144
00:06:21,960 --> 00:06:26,819
it's trying to add a tuple to a number

145
00:06:25,319 --> 00:06:29,580
this is

146
00:06:26,819 --> 00:06:31,139
this is a less worse error than those

147
00:06:29,580 --> 00:06:34,800
previous ones because our code won't

148
00:06:31,139 --> 00:06:37,680
execute that's a good thing

149
00:06:34,800 --> 00:06:40,259
anyway we've had three hard to spot bugs

150
00:06:37,680 --> 00:06:42,240
in Trivial code

151
00:06:40,259 --> 00:06:44,880
these bugs would never have occurred in

152
00:06:42,240 --> 00:06:47,940
a compiled language like Pascal which is

153
00:06:44,880 --> 00:06:50,280
my background or C or C sharp as the

154
00:06:47,940 --> 00:06:54,000
compiler would have caught them

155
00:06:50,280 --> 00:06:56,160
what happens when the body of code grows

156
00:06:54,000 --> 00:06:59,880
what happens when the number of code is

157
00:06:56,160 --> 00:07:01,560
on your team grows from one to n and

158
00:06:59,880 --> 00:07:04,100
what happens if you're simply having a

159
00:07:01,560 --> 00:07:04,100
bad day

160
00:07:05,759 --> 00:07:09,660
back to the question at the start of the

161
00:07:07,620 --> 00:07:12,240
talk

162
00:07:09,660 --> 00:07:14,220
what is the hardest question for a coder

163
00:07:12,240 --> 00:07:16,080
to answer

164
00:07:14,220 --> 00:07:17,400
in my experience

165
00:07:16,080 --> 00:07:19,440
it's this

166
00:07:17,400 --> 00:07:21,539
are you done

167
00:07:19,440 --> 00:07:23,639
the answer always comes with a caveat

168
00:07:21,539 --> 00:07:25,620
yes I'm done but I haven't finished the

169
00:07:23,639 --> 00:07:28,199
unit test yes I'm done but I have some

170
00:07:25,620 --> 00:07:30,419
documentation to write yes I'm done but

171
00:07:28,199 --> 00:07:32,759
oh my goodness I have to refactor this

172
00:07:30,419 --> 00:07:37,560
module over to the side

173
00:07:32,759 --> 00:07:40,080
what we want is an objective unambiguous

174
00:07:37,560 --> 00:07:41,699
definition of done

175
00:07:40,080 --> 00:07:43,860
something that we all agree to see

176
00:07:41,699 --> 00:07:44,639
something is all your team members agree

177
00:07:43,860 --> 00:07:48,620
to

178
00:07:44,639 --> 00:07:48,620
to allow this question to be answered

179
00:07:49,979 --> 00:07:53,940
about these six and they're going to

180
00:07:52,259 --> 00:07:54,720
help us answer that question are you

181
00:07:53,940 --> 00:07:57,360
done

182
00:07:54,720 --> 00:07:59,759
the tools that I saw black Pile in my

183
00:07:57,360 --> 00:08:01,620
pipe Pi test and coverage we're going to

184
00:07:59,759 --> 00:08:04,259
look at each one and look at the changes

185
00:08:01,620 --> 00:08:05,639
those tools will make to the code as you

186
00:08:04,259 --> 00:08:07,800
execute them

187
00:08:05,639 --> 00:08:09,539
I thought as the first one and it's the

188
00:08:07,800 --> 00:08:12,479
simplest this is the blurb of the

189
00:08:09,539 --> 00:08:14,639
eyesort website I saw it as a python

190
00:08:12,479 --> 00:08:16,500
utility or library to sort Imports

191
00:08:14,639 --> 00:08:18,539
alphabetically and automatically

192
00:08:16,500 --> 00:08:21,900
separate them into sections by type

193
00:08:18,539 --> 00:08:24,479
that's all a bit ho-hum you can

194
00:08:21,900 --> 00:08:26,099
implement the same behavior as I sort

195
00:08:24,479 --> 00:08:29,220
will give you with Control Alt something

196
00:08:26,099 --> 00:08:30,720
other in your IDE

197
00:08:29,220 --> 00:08:33,779
um

198
00:08:30,720 --> 00:08:35,399
it will sort your imported or get rid of

199
00:08:33,779 --> 00:08:37,979
the ones that aren't used it will

200
00:08:35,399 --> 00:08:39,779
eliminate git noise that's the main

201
00:08:37,979 --> 00:08:41,580
reason for use this you're not going to

202
00:08:39,779 --> 00:08:44,039
get any git conflicts in your import

203
00:08:41,580 --> 00:08:47,360
section when you've used this install

204
00:08:44,039 --> 00:08:47,360
use it and move on

205
00:08:47,640 --> 00:08:50,820
black takes over your life a little bit

206
00:08:49,740 --> 00:08:53,000
more

207
00:08:50,820 --> 00:08:56,399
black is the uncompromising

208
00:08:53,000 --> 00:08:58,680
uncompromising python code formator by

209
00:08:56,399 --> 00:09:01,440
using it you agree to see control over

210
00:08:58,680 --> 00:09:04,320
the minutia of hand formatting in return

211
00:09:01,440 --> 00:09:06,480
black gives you speed certainty and

212
00:09:04,320 --> 00:09:08,880
freedom from get noise that git thing

213
00:09:06,480 --> 00:09:10,980
again black will save you time and

214
00:09:08,880 --> 00:09:14,300
mental energy freeing you for more

215
00:09:10,980 --> 00:09:16,500
important matters

216
00:09:14,300 --> 00:09:20,040
let's have a look at some code before

217
00:09:16,500 --> 00:09:21,660
and after we execute black

218
00:09:20,040 --> 00:09:24,959
so our little fragment of code that

219
00:09:21,660 --> 00:09:26,640
parses that text file with the generator

220
00:09:24,959 --> 00:09:28,920
class has been run through black and

221
00:09:26,640 --> 00:09:30,660
it's done two things to it it's injected

222
00:09:28,920 --> 00:09:33,839
a blank line ahead of the class

223
00:09:30,660 --> 00:09:37,320
definition that's pep eight thing it's a

224
00:09:33,839 --> 00:09:39,959
bit ho-hum but it will solve get noise

225
00:09:37,320 --> 00:09:42,899
and it has reformatted the dunder string

226
00:09:39,959 --> 00:09:45,839
method that I've added to my class I

227
00:09:42,899 --> 00:09:48,000
started off with a long uh

228
00:09:45,839 --> 00:09:50,339
long line of code that spanned I don't

229
00:09:48,000 --> 00:09:51,779
know 80 90 characters and black has

230
00:09:50,339 --> 00:09:54,060
wrapped it for me and it's wrapped it

231
00:09:51,779 --> 00:09:56,700
for me in a consistent way

232
00:09:54,060 --> 00:09:58,140
a little bit ho-hum perhaps but again it

233
00:09:56,700 --> 00:10:00,899
will get rid of git noise and it will

234
00:09:58,140 --> 00:10:03,899
stop arguments over formatting Styles

235
00:10:00,899 --> 00:10:06,180
within your team it also allows you as

236
00:10:03,899 --> 00:10:07,980
your coding to just type any old

237
00:10:06,180 --> 00:10:10,320
nonsense run it get the thing working

238
00:10:07,980 --> 00:10:12,779
and then hit black and it's formatted

239
00:10:10,320 --> 00:10:14,040
for you so it actually it does save a

240
00:10:12,779 --> 00:10:16,320
lot of time because you don't have to

241
00:10:14,040 --> 00:10:18,360
stress over do I enter a carriage return

242
00:10:16,320 --> 00:10:20,540
here or should I be continuing on the

243
00:10:18,360 --> 00:10:20,540
line

244
00:10:20,700 --> 00:10:25,440
again black a little bit ho-hum install

245
00:10:22,860 --> 00:10:27,180
it use it move on

246
00:10:25,440 --> 00:10:28,500
piling is starting to get a bit more

247
00:10:27,180 --> 00:10:31,880
interesting

248
00:10:28,500 --> 00:10:35,160
piling has a is a python static code

249
00:10:31,880 --> 00:10:37,740
analysis tool which looks for form looks

250
00:10:35,160 --> 00:10:40,080
for programming errors it helps enforce

251
00:10:37,740 --> 00:10:43,380
coding standards it sniffs for code

252
00:10:40,080 --> 00:10:46,220
smells and it offers simple refactoring

253
00:10:43,380 --> 00:10:46,220
suggestions

254
00:10:46,320 --> 00:10:51,480
now a good ide will give you isort black

255
00:10:49,260 --> 00:10:55,260
and pilint support

256
00:10:51,480 --> 00:10:57,420
this is part charm and you can see line

257
00:10:55,260 --> 00:11:00,779
six there's a squiggly yellow line under

258
00:10:57,420 --> 00:11:04,220
my class definition if I hover the mouse

259
00:11:00,779 --> 00:11:07,260
it tells me pep 8.

260
00:11:04,220 --> 00:11:10,260
e302 expected two blank lines one found

261
00:11:07,260 --> 00:11:12,480
well that's easy to fix and it tells you

262
00:11:10,260 --> 00:11:14,640
another one class names should use camel

263
00:11:12,480 --> 00:11:16,920
case convention okay that's a little bit

264
00:11:14,640 --> 00:11:20,640
harder to fix you've got to control or

265
00:11:16,920 --> 00:11:22,620
whatever the rename is in pycharm and

266
00:11:20,640 --> 00:11:24,860
change that class name all through your

267
00:11:22,620 --> 00:11:24,860
code

268
00:11:25,459 --> 00:11:30,060
pilint will run in the IDE as I just

269
00:11:28,079 --> 00:11:33,420
showed you but also run as a batch

270
00:11:30,060 --> 00:11:35,339
script outside the IDE and we do both on

271
00:11:33,420 --> 00:11:37,980
our project pilot will give an error

272
00:11:35,339 --> 00:11:40,200
message like this it's the file name

273
00:11:37,980 --> 00:11:42,899
followed by the line number and the

274
00:11:40,200 --> 00:11:45,000
column number you can copy that to the

275
00:11:42,899 --> 00:11:46,800
clipboard and control alt something or

276
00:11:45,000 --> 00:11:49,019
other in pycharm and it'll take you to

277
00:11:46,800 --> 00:11:53,940
the exact location it gives you a

278
00:11:49,019 --> 00:11:56,279
numeric warning a message ID it gives

279
00:11:53,940 --> 00:11:58,440
you a human readable message description

280
00:11:56,279 --> 00:12:01,140
and then it gives you a text-based

281
00:11:58,440 --> 00:12:03,779
message ID also you can use that

282
00:12:01,140 --> 00:12:06,000
text-based message ID to suppress this

283
00:12:03,779 --> 00:12:08,660
form of Warning by inserting a comment

284
00:12:06,000 --> 00:12:08,660
into your code

285
00:12:10,019 --> 00:12:16,019
messages from our sample code

286
00:12:12,899 --> 00:12:19,920
the first one trailing new lines to bit

287
00:12:16,019 --> 00:12:23,160
ho-hum the second one disallowed

288
00:12:19,920 --> 00:12:25,740
trailing comma Tuple that's interesting

289
00:12:23,160 --> 00:12:28,019
that's a real bug that pilant has

290
00:12:25,740 --> 00:12:29,700
spotted for us that that absolutely

291
00:12:28,019 --> 00:12:32,160
needs to be fixed

292
00:12:29,700 --> 00:12:35,279
uh the next one redefining a built-in

293
00:12:32,160 --> 00:12:37,079
sum okay so the word sum is a python

294
00:12:35,279 --> 00:12:39,180
Library thing and I have a variable that

295
00:12:37,079 --> 00:12:42,180
clashes with that so that should be tied

296
00:12:39,180 --> 00:12:44,760
it up constant name input underscore

297
00:12:42,180 --> 00:12:48,240
file doesn't conform to uppercase naming

298
00:12:44,760 --> 00:12:51,180
style ho-hum but let's fix it missing

299
00:12:48,240 --> 00:12:54,860
doc string we have a rule on our project

300
00:12:51,180 --> 00:12:57,000
that all classes must have documentation

301
00:12:54,860 --> 00:12:58,800
pilot wants a higher level of

302
00:12:57,000 --> 00:13:01,800
documentation than that but we've wound

303
00:12:58,800 --> 00:13:04,200
that back to only requiring

304
00:13:01,800 --> 00:13:05,459
documentation for classes and there's a

305
00:13:04,200 --> 00:13:06,600
couple of other ones that are getting

306
00:13:05,459 --> 00:13:07,339
into the

307
00:13:06,600 --> 00:13:10,139
um

308
00:13:07,339 --> 00:13:12,180
uh semantic thing rather than hardcore

309
00:13:10,139 --> 00:13:14,459
bugs but we have a policy of tidying

310
00:13:12,180 --> 00:13:16,980
them up anyway because that noise could

311
00:13:14,459 --> 00:13:20,839
be hiding something like our trailing

312
00:13:16,980 --> 00:13:20,839
comma that actually matters

313
00:13:21,899 --> 00:13:27,240
progress between runs with this message

314
00:13:24,540 --> 00:13:30,740
here your code has been rated 10 out of

315
00:13:27,240 --> 00:13:30,740
10. previous run

316
00:13:31,700 --> 00:13:38,339
99.98 out of 10. it kind of gamifies the

317
00:13:35,579 --> 00:13:41,040
quality process so our team members

318
00:13:38,339 --> 00:13:45,540
collectively get this wonderful surge of

319
00:13:41,040 --> 00:13:48,540
happy hormones as our as our progress

320
00:13:45,540 --> 00:13:51,000
tracks put towards 10 out of 10 or 100

321
00:13:48,540 --> 00:13:52,980
percent

322
00:13:51,000 --> 00:13:53,940
here's a fragment of code before and

323
00:13:52,980 --> 00:13:55,800
after

324
00:13:53,940 --> 00:13:57,300
pilot

325
00:13:55,800 --> 00:14:00,180
before and after the human intervention

326
00:13:57,300 --> 00:14:02,399
to correct pylent errors again bit

327
00:14:00,180 --> 00:14:05,399
ho-hum I've changed the name of the

328
00:14:02,399 --> 00:14:08,040
input file variable to conform with pep

329
00:14:05,399 --> 00:14:11,100
8 all uppercase I've changed my class

330
00:14:08,040 --> 00:14:14,720
name to Pascal case and I've inserted a

331
00:14:11,100 --> 00:14:14,720
comma that comma a comment

332
00:14:15,120 --> 00:14:19,320
pilint allows you to write custom

333
00:14:17,100 --> 00:14:21,959
linters and we do this quite a bit on

334
00:14:19,320 --> 00:14:24,660
our project too one of our staffing

335
00:14:21,959 --> 00:14:26,820
patterns is that we rotate our power

336
00:14:24,660 --> 00:14:29,339
system engineer graduates through the

337
00:14:26,820 --> 00:14:31,860
team who all come with coding skills but

338
00:14:29,339 --> 00:14:35,579
not necessarily Enterprise type coding

339
00:14:31,860 --> 00:14:37,500
skills and during peer reviews or peer

340
00:14:35,579 --> 00:14:39,720
reviews of the code we've found

341
00:14:37,500 --> 00:14:41,639
ourselves over and over again explaining

342
00:14:39,720 --> 00:14:44,339
look please don't build up a file name

343
00:14:41,639 --> 00:14:46,680
like that use Python's pathlib or please

344
00:14:44,339 --> 00:14:49,019
don't create a python class like that

345
00:14:46,680 --> 00:14:52,079
use a data class or please don't

346
00:14:49,019 --> 00:14:55,860
concatenate strings like that use F

347
00:14:52,079 --> 00:14:58,800
string so we have a series of custom

348
00:14:55,860 --> 00:15:01,380
linters that pylin executes that

349
00:14:58,800 --> 00:15:04,019
supports the new coder towards our

350
00:15:01,380 --> 00:15:06,180
coding standards and relieves time

351
00:15:04,019 --> 00:15:08,160
during the peer review process for

352
00:15:06,180 --> 00:15:10,699
matters of architectural significance

353
00:15:08,160 --> 00:15:15,079
rather than just

354
00:15:10,699 --> 00:15:15,079
how did you concatenate a string

355
00:15:15,600 --> 00:15:19,500
after running the customer letters a

356
00:15:17,940 --> 00:15:22,860
code looks like this

357
00:15:19,500 --> 00:15:25,220
the input file now has become a python

358
00:15:22,860 --> 00:15:28,500
path object

359
00:15:25,220 --> 00:15:30,839
because it's a python path object we can

360
00:15:28,500 --> 00:15:34,680
open it as a file and iterate it using a

361
00:15:30,839 --> 00:15:37,320
slightly different tersa syntax as shown

362
00:15:34,680 --> 00:15:39,600
on line 26.

363
00:15:37,320 --> 00:15:42,600
and we've created an instance of our

364
00:15:39,600 --> 00:15:44,880
class using the new format where we're

365
00:15:42,600 --> 00:15:49,380
passing important data into the

366
00:15:44,880 --> 00:15:49,380
Constructor on line 30.

367
00:15:50,820 --> 00:15:56,279
my pie is where things start to get more

368
00:15:53,339 --> 00:15:58,320
interesting still my pie is a static

369
00:15:56,279 --> 00:16:00,600
type Checker your note your code with

370
00:15:58,320 --> 00:16:02,300
typings and my Pi will check for bugs

371
00:16:00,600 --> 00:16:05,220
caused by type

372
00:16:02,300 --> 00:16:08,579
incompatibility here are some typical my

373
00:16:05,220 --> 00:16:10,399
Pi messages function is missing a type

374
00:16:08,579 --> 00:16:15,120
annotation

375
00:16:10,399 --> 00:16:17,820
or incompatible type assignment

376
00:16:15,120 --> 00:16:19,740
some code before and after we've run it

377
00:16:17,820 --> 00:16:21,360
through mypine manually made the

378
00:16:19,740 --> 00:16:24,480
necessary changes

379
00:16:21,360 --> 00:16:28,139
our Dundas LT method has got some

380
00:16:24,480 --> 00:16:30,180
typings now so the other attribute or

381
00:16:28,139 --> 00:16:33,600
the other argument that's passed in must

382
00:16:30,180 --> 00:16:34,800
be of type gen and it must return a

383
00:16:33,600 --> 00:16:37,380
Boolean

384
00:16:34,800 --> 00:16:40,500
while we're here we've created a generic

385
00:16:37,380 --> 00:16:43,079
based list of our generators so we can

386
00:16:40,500 --> 00:16:46,639
pass this we can use this list in our

387
00:16:43,079 --> 00:16:49,320
code without having to um

388
00:16:46,639 --> 00:16:51,839
type the list

389
00:16:49,320 --> 00:16:54,120
differently all through our all through

390
00:16:51,839 --> 00:16:55,980
our coder that grows and we've created

391
00:16:54,120 --> 00:16:59,360
an instance of our list of the correct

392
00:16:55,980 --> 00:16:59,360
type down the bottom

393
00:16:59,899 --> 00:17:03,779
Pi test is a unit test framework for

394
00:17:02,759 --> 00:17:06,179
python

395
00:17:03,779 --> 00:17:08,520
High test framework makes it easy to

396
00:17:06,179 --> 00:17:10,559
write small tests while scaling to

397
00:17:08,520 --> 00:17:15,120
support unit integration regression

398
00:17:10,559 --> 00:17:17,459
testing of a full program Suite

399
00:17:15,120 --> 00:17:19,079
now to run Pi test against your code

400
00:17:17,459 --> 00:17:22,079
you're probably going to have to change

401
00:17:19,079 --> 00:17:24,179
the structure of your code this is where

402
00:17:22,079 --> 00:17:25,319
the tools really start to take over your

403
00:17:24,179 --> 00:17:28,400
life

404
00:17:25,319 --> 00:17:30,660
code was initially a large script

405
00:17:28,400 --> 00:17:33,419
execution would start at the top it

406
00:17:30,660 --> 00:17:35,039
would work through to the bottom and the

407
00:17:33,419 --> 00:17:36,539
lines at the bottom would be the entry

408
00:17:35,039 --> 00:17:40,160
point and would call the code

409
00:17:36,539 --> 00:17:43,380
procedurally one line after the other

410
00:17:40,160 --> 00:17:45,179
that is very hard to unit test code in

411
00:17:43,380 --> 00:17:46,919
that style because you don't have a

412
00:17:45,179 --> 00:17:50,280
thing that you can grasp hold of and

413
00:17:46,919 --> 00:17:52,440
pass around you can't create an instance

414
00:17:50,280 --> 00:17:55,799
of it in your unit tests and poke it

415
00:17:52,440 --> 00:17:59,160
with the testing patterns

416
00:17:55,799 --> 00:18:01,320
so we break our code from one file into

417
00:17:59,160 --> 00:18:04,740
four

418
00:18:01,320 --> 00:18:06,600
we start with a an entry point file you

419
00:18:04,740 --> 00:18:09,000
know called done dismayne in this case

420
00:18:06,600 --> 00:18:12,720
we have a file that contains the unit

421
00:18:09,000 --> 00:18:15,120
tests test underscore gen in this case

422
00:18:12,720 --> 00:18:18,000
we have a file that contains our data

423
00:18:15,120 --> 00:18:20,340
test underscore bomb a naming standard

424
00:18:18,000 --> 00:18:22,200
we use on our project bomb means

425
00:18:20,340 --> 00:18:23,880
business object model

426
00:18:22,200 --> 00:18:25,140
and then we have a file that contains

427
00:18:23,880 --> 00:18:27,539
the behavior

428
00:18:25,140 --> 00:18:29,340
gen to total

429
00:18:27,539 --> 00:18:32,039
so the pattern we use is that we

430
00:18:29,340 --> 00:18:35,960
separate data from Behavior nouns from

431
00:18:32,039 --> 00:18:35,960
verbs in our code

432
00:18:37,039 --> 00:18:42,780
our gen bomb file contains the code that

433
00:18:40,740 --> 00:18:44,780
we created earlier on in our big

434
00:18:42,780 --> 00:18:47,880
procedural script

435
00:18:44,780 --> 00:18:52,160
definition of our gen class and the

436
00:18:47,880 --> 00:18:55,260
definition of our gen list

437
00:18:52,160 --> 00:18:57,660
our Behavior has been wrapped up into a

438
00:18:55,260 --> 00:19:00,600
class called gen to total

439
00:18:57,660 --> 00:19:03,240
it has a it has a entry point called

440
00:19:00,600 --> 00:19:05,039
execute again the standard we use across

441
00:19:03,240 --> 00:19:07,440
our team if you have a class that

442
00:19:05,039 --> 00:19:09,419
contains Behavior it has a entry point

443
00:19:07,440 --> 00:19:12,299
called execute

444
00:19:09,419 --> 00:19:14,640
execute takes a single argument passed

445
00:19:12,299 --> 00:19:17,400
to the input file and it returns a

446
00:19:14,640 --> 00:19:20,520
single value of death of type decimal

447
00:19:17,400 --> 00:19:23,880
which is the sum of all the generations

448
00:19:20,520 --> 00:19:26,160
for that trading period as execute grows

449
00:19:23,880 --> 00:19:28,620
you can break it down into a number of

450
00:19:26,160 --> 00:19:30,960
methods that are private to the Gen to

451
00:19:28,620 --> 00:19:33,919
Total class you've got to do what you've

452
00:19:30,960 --> 00:19:33,919
got to do for readability

453
00:19:35,880 --> 00:19:41,400
anything remarkable here if name equals

454
00:19:38,280 --> 00:19:43,320
main create a reference to the file that

455
00:19:41,400 --> 00:19:45,780
we want to read in reality you might

456
00:19:43,320 --> 00:19:48,140
want to parameterize that somehow create

457
00:19:45,780 --> 00:19:51,179
an instance of our gender total class

458
00:19:48,140 --> 00:19:52,880
execute our gender total class grab the

459
00:19:51,179 --> 00:19:56,340
value print the value to the screen

460
00:19:52,880 --> 00:19:59,520
nothing remarkable there

461
00:19:56,340 --> 00:20:00,919
our test code looks like this using the

462
00:19:59,520 --> 00:20:03,600
pi test

463
00:20:00,919 --> 00:20:07,820
standard we have a container class

464
00:20:03,600 --> 00:20:11,340
called test gen read Pi test requires

465
00:20:07,820 --> 00:20:15,059
the first part of a class that's part of

466
00:20:11,340 --> 00:20:17,160
a test to be Capital t-e-s-t it has a

467
00:20:15,059 --> 00:20:19,260
method or a bunch of methods on it that

468
00:20:17,160 --> 00:20:22,440
can execute our test code Pi test

469
00:20:19,260 --> 00:20:25,919
requires test underscore whatever as

470
00:20:22,440 --> 00:20:31,220
part of its naming style line 21 we're

471
00:20:25,919 --> 00:20:34,380
creating an input file with known data

472
00:20:31,220 --> 00:20:36,960
that variable content contains three

473
00:20:34,380 --> 00:20:39,360
lines of text that sets up our input

474
00:20:36,960 --> 00:20:41,100
file with values that we have control

475
00:20:39,360 --> 00:20:45,179
over

476
00:20:41,100 --> 00:20:47,940
line 20 contains a pi test

477
00:20:45,179 --> 00:20:51,179
fixture called temp path

478
00:20:47,940 --> 00:20:53,700
temppath is a path to a temporary folder

479
00:20:51,179 --> 00:20:55,260
that Pi test has created for us and Pi

480
00:20:53,700 --> 00:20:57,660
test will take responsibility for

481
00:20:55,260 --> 00:20:59,700
cleaning up

482
00:20:57,660 --> 00:21:02,400
we create an instance of our gen to

483
00:20:59,700 --> 00:21:04,980
Total class and line 25 we execute and

484
00:21:02,400 --> 00:21:07,200
capture the value and then on line 28 we

485
00:21:04,980 --> 00:21:10,039
compare the value against an expected

486
00:21:07,200 --> 00:21:12,480
answer

487
00:21:10,039 --> 00:21:14,520
and our test passes

488
00:21:12,480 --> 00:21:17,940
and of course we have many many tests

489
00:21:14,520 --> 00:21:22,080
like this in a production body of code

490
00:21:17,940 --> 00:21:24,600
again to execute to work in this way we

491
00:21:22,080 --> 00:21:26,280
must refactor our code and just a

492
00:21:24,600 --> 00:21:28,679
reminder this the pattern is we have an

493
00:21:26,280 --> 00:21:31,940
entry point we have tests we have data

494
00:21:28,679 --> 00:21:31,940
and we have Behavior

495
00:21:33,179 --> 00:21:37,500
it is the last tool in the suite

496
00:21:35,460 --> 00:21:40,500
coverage is a tool for measuring code

497
00:21:37,500 --> 00:21:42,780
that is actually executed in Python

498
00:21:40,500 --> 00:21:45,120
coverage monitors the program while it

499
00:21:42,780 --> 00:21:46,620
executes noting which parts of the code

500
00:21:45,120 --> 00:21:49,559
have been run

501
00:21:46,620 --> 00:21:53,299
it produces a report listing code that

502
00:21:49,559 --> 00:21:53,299
could have been run but wasn't

503
00:21:53,460 --> 00:21:58,080
coverage report on our frag on our test

504
00:21:55,679 --> 00:22:00,059
code looks like this

505
00:21:58,080 --> 00:22:03,200
you can see we've got coverage of 93

506
00:22:00,059 --> 00:22:07,580
percent and we're missing lines 8 to 11

507
00:22:03,200 --> 00:22:07,580
of Dundas Maine

508
00:22:08,220 --> 00:22:13,679
how are we going to hit those lines

509
00:22:10,740 --> 00:22:15,900
things start getting a little trickier

510
00:22:13,679 --> 00:22:18,059
the code at the top shows the entry

511
00:22:15,900 --> 00:22:20,340
point as we coded it

512
00:22:18,059 --> 00:22:23,280
early on

513
00:22:20,340 --> 00:22:26,820
if name equals main creating reference

514
00:22:23,280 --> 00:22:29,820
to the file an instance of the reader

515
00:22:26,820 --> 00:22:31,740
executed print the answer

516
00:22:29,820 --> 00:22:34,460
we need a way of grabbing hold of that

517
00:22:31,740 --> 00:22:37,380
code in pi test and poking it

518
00:22:34,460 --> 00:22:39,780
so to achieve that we've wrapped it all

519
00:22:37,380 --> 00:22:43,200
in a method called Main

520
00:22:39,780 --> 00:22:45,480
same code is just contained in a in a

521
00:22:43,200 --> 00:22:48,080
function called Main and the entry point

522
00:22:45,480 --> 00:22:51,960
calls that function on line 14.

523
00:22:48,080 --> 00:22:53,340
this allows us to write a unit test like

524
00:22:51,960 --> 00:22:56,640
this

525
00:22:53,340 --> 00:23:01,620
we use Python's import lib

526
00:22:56,640 --> 00:23:03,780
module to import our Dundas main file as

527
00:23:01,620 --> 00:23:06,900
if it was a module

528
00:23:03,780 --> 00:23:09,020
we then use Python's mock library to

529
00:23:06,900 --> 00:23:12,299
change the name of the doneness name

530
00:23:09,020 --> 00:23:14,700
attribute on that file to Main

531
00:23:12,299 --> 00:23:18,840
we then hit the main

532
00:23:14,700 --> 00:23:20,880
method the main function in that file

533
00:23:18,840 --> 00:23:23,280
a pi test has another fixture called

534
00:23:20,880 --> 00:23:25,220
capsis which will capture anything

535
00:23:23,280 --> 00:23:29,700
that's printed to the screen

536
00:23:25,220 --> 00:23:31,919
so line 35 we're reading the contents of

537
00:23:29,700 --> 00:23:35,039
what was printed to the screen

538
00:23:31,919 --> 00:23:36,720
it gives you two outputs what was

539
00:23:35,039 --> 00:23:38,700
printed to stand it out and what was

540
00:23:36,720 --> 00:23:40,380
printed to standard error

541
00:23:38,700 --> 00:23:44,400
we checked the contents of standard

542
00:23:40,380 --> 00:23:47,120
error against our expected value and our

543
00:23:44,400 --> 00:23:47,120
test passes

544
00:23:47,760 --> 00:23:52,380
which now reports 100 percent

545
00:23:50,280 --> 00:23:53,520
coverage

546
00:23:52,380 --> 00:23:55,460
now

547
00:23:53,520 --> 00:23:59,280
there'll be a question within your team

548
00:23:55,460 --> 00:24:01,260
what level of coverage is sufficient

549
00:23:59,280 --> 00:24:03,539
when we started this

550
00:24:01,260 --> 00:24:06,179
we had our unit test and we had almost

551
00:24:03,539 --> 00:24:08,940
prod quality code we had a coverage of

552
00:24:06,179 --> 00:24:10,799
around about 95 percent

553
00:24:08,940 --> 00:24:13,500
we all pulled our efforts and spent a

554
00:24:10,799 --> 00:24:15,299
day and we got it up to 98 percent

555
00:24:13,500 --> 00:24:17,039
and then we did some soul searching how

556
00:24:15,299 --> 00:24:20,400
far do we want to take this because

557
00:24:17,039 --> 00:24:22,620
we're spending our employers money and

558
00:24:20,400 --> 00:24:25,559
to reach that extra two percent we're

559
00:24:22,620 --> 00:24:27,120
starting to spend serious money

560
00:24:25,559 --> 00:24:29,700
but

561
00:24:27,120 --> 00:24:31,799
well and so we decided to give it a go

562
00:24:29,700 --> 00:24:33,059
so we time boxed it we said by the end

563
00:24:31,799 --> 00:24:34,980
of the week if we don't have 100

564
00:24:33,059 --> 00:24:37,380
coverage we're going to back off and

565
00:24:34,980 --> 00:24:40,559
lower our quality standards

566
00:24:37,380 --> 00:24:42,120
we achieved 100 coverage there were some

567
00:24:40,559 --> 00:24:44,220
patterns we had to nut through

568
00:24:42,120 --> 00:24:45,480
particularly that how to hit an entry

569
00:24:44,220 --> 00:24:48,240
point

570
00:24:45,480 --> 00:24:50,820
but this has become our quality metric

571
00:24:48,240 --> 00:24:55,220
from that day forward code doesn't go to

572
00:24:50,820 --> 00:24:55,220
production unless it has 100 coverage

573
00:24:55,320 --> 00:25:00,720
do I have to do this really is often

574
00:24:58,320 --> 00:25:03,480
asked by the new members of our team

575
00:25:00,720 --> 00:25:07,080
this is seriously expensive

576
00:25:03,480 --> 00:25:09,419
and the answer is absolutely yes you

577
00:25:07,080 --> 00:25:11,940
have to do this for our code base

578
00:25:09,419 --> 00:25:16,919
for many reasons but one is that your

579
00:25:11,940 --> 00:25:21,059
code will last a long long time

580
00:25:16,919 --> 00:25:23,539
December 17 1999 is the birthday of the

581
00:25:21,059 --> 00:25:25,980
system we support

582
00:25:23,539 --> 00:25:30,419
23 years old and the code that was

583
00:25:25,980 --> 00:25:33,000
written prior to December 17 1999 Pascal

584
00:25:30,419 --> 00:25:36,240
code is still in production and is still

585
00:25:33,000 --> 00:25:38,700
producing value for the organization so

586
00:25:36,240 --> 00:25:43,020
we write our python code as if it's

587
00:25:38,700 --> 00:25:47,480
going to last 25 years or more

588
00:25:43,020 --> 00:25:50,760
what's the lifetime spend on QA

589
00:25:47,480 --> 00:25:54,419
aimo's amp code base the project I work

590
00:25:50,760 --> 00:25:55,679
on now has 71 000 lines of production

591
00:25:54,419 --> 00:25:59,520
source

592
00:25:55,679 --> 00:26:02,580
it has 52 000 lines of unit tests that's

593
00:25:59,520 --> 00:26:05,179
around about 40 of our code is unit

594
00:26:02,580 --> 00:26:05,179
tests

595
00:26:05,520 --> 00:26:09,840
back to this question the hardest

596
00:26:07,500 --> 00:26:12,960
question for a coda to answer

597
00:26:09,840 --> 00:26:16,080
are you done we now have

598
00:26:12,960 --> 00:26:17,880
an unambiguous objective way of

599
00:26:16,080 --> 00:26:21,299
answering that question

600
00:26:17,880 --> 00:26:25,679
I thought it's clean it's black is clean

601
00:26:21,299 --> 00:26:28,200
is clean my pie is clean you have unit

602
00:26:25,679 --> 00:26:30,360
tests and coverage is at a hundred

603
00:26:28,200 --> 00:26:32,820
percent

604
00:26:30,360 --> 00:26:35,220
we can talk about

605
00:26:32,820 --> 00:26:37,620
the cost of peer review user acceptance

606
00:26:35,220 --> 00:26:39,840
testing load testing cyber testing

607
00:26:37,620 --> 00:26:41,400
integration testing usability testing

608
00:26:39,840 --> 00:26:44,940
and all those other things you do before

609
00:26:41,400 --> 00:26:46,799
you're truly done later but this is a

610
00:26:44,940 --> 00:26:49,400
tool for the coder

611
00:26:46,799 --> 00:26:49,400
thank you

612
00:26:54,260 --> 00:26:59,779
thanks Peter we have some time for

613
00:26:57,000 --> 00:26:59,779
questions yes

614
00:27:00,539 --> 00:27:03,799
did anyone have a question

615
00:27:08,760 --> 00:27:14,220
um do you uh

616
00:27:11,159 --> 00:27:16,980
maintain the same level of checking for

617
00:27:14,220 --> 00:27:19,980
products and related issues how do we

618
00:27:16,980 --> 00:27:21,779
how do you fix those in case

619
00:27:19,980 --> 00:27:23,340
say that again if you could in case

620
00:27:21,779 --> 00:27:26,220
there is a products and related issue

621
00:27:23,340 --> 00:27:28,460
and you need to push a chance rather

622
00:27:26,220 --> 00:27:28,460
quick

623
00:27:28,500 --> 00:27:33,720
uh yes we do

624
00:27:30,299 --> 00:27:36,000
um we have a git row repo of course we

625
00:27:33,720 --> 00:27:38,580
use git flow so we have a series of

626
00:27:36,000 --> 00:27:40,440
branches we have feature branches hot

627
00:27:38,580 --> 00:27:43,500
fixes going on

628
00:27:40,440 --> 00:27:46,620
release branches if we have a prod type

629
00:27:43,500 --> 00:27:48,620
quality will create a hotfix

630
00:27:46,620 --> 00:27:51,600
we'll implement the fix

631
00:27:48,620 --> 00:27:54,299
this is absolutely a quality metric that

632
00:27:51,600 --> 00:27:56,039
everything that goes to prod has to

633
00:27:54,299 --> 00:27:58,080
has to go through

634
00:27:56,039 --> 00:27:59,760
um you think it's an overhead and it's a

635
00:27:58,080 --> 00:28:02,039
burden and it's going to cost more than

636
00:27:59,760 --> 00:28:04,200
it saves but because we have this

637
00:28:02,039 --> 00:28:07,220
we're able to implement that prod fix

638
00:28:04,200 --> 00:28:07,220
very quickly

639
00:28:09,100 --> 00:28:12,240
[Music]

640
00:28:13,500 --> 00:28:18,679
looks like we've hit our definition of

641
00:28:15,120 --> 00:28:18,679
done no questions I think so

642
00:28:23,400 --> 00:28:27,659
so much Peter it was a lovely talk thank

643
00:28:25,559 --> 00:28:30,740
you

644
00:28:27,659 --> 00:28:30,740
thank you very much