about summary refs log tree commit diff stats
path: root/003trace.cc
blob: af707354c7af45561b189639d9aeaedc75f1bff4 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
//: The goal of layers is to make programs more easy to understand and more
//: malleable, easy to rewrite in radical ways without accidentally breaking
//: some corner case. Tests further both goals. They help understandability by
//: letting one make small changes and get feedback. What if I wrote this line
//: like so? What if I removed this function call, is it really necessary?
//: Just try it, see if the tests pass. Want to explore rewriting this bit in
//: this way? Tests put many refactorings on a firmer footing.
//:
//: But the usual way we write tests seems incomplete. Refactorings tend to
//: work in the small, but don't help with changes to function boundaries. If
//: you want to extract a new function you have to manually test-drive it to
//: create tests for it. If you want to inline a function its tests are no
//: longer valid. In both cases you end up having to reorganize code as well as
//: tests, an error-prone activity.
//:
//: In response, this layer introduces the notion of domain-driven *white-box*
//: testing. We focus on the domain of inputs the whole program needs to
//: handle rather than the correctness of individual functions. All white-box
//: tests (we call them 'scenarios') invoke the program in a single way: by
//: calling run() with some input. As the program operates on the input, it
//: traces out a list of _facts_ deduced about the domain:
//:   trace("label") << "fact 1: " << val;
//:
//: Scenarios can now check these facts:
//:   :(scenario foo)
//:   34  # call run() with this input
//:   +label: fact 1: 34  # 'run' should have deduced this fact
//:   -label: fact 1: 35  # the trace should not contain such a fact
//:
//: Since we never call anything but the run() function directly, we never have
//: to rewrite the scenarios when we reorganize the internals of the program. We
//: just have to make sure our rewrite deduces the same facts about the domain,
//: and that's something we're going to have to do anyway.
//:
//: To avoid the combinatorial explosion of integration tests, each layer
//: mainly logs facts to the trace with a common *label*. All scenarios in a
//: layer tend to check facts with this label. Validating the facts logged
//: with a specific label is like calling functions of that layer directly.
//:
//: To build robust scenarios, trace facts about your domain rather than details of
//: how you computed them.
//:
//: More details: http://akkartik.name/blog/tracing-tests
//:
//: ---
//:
//: Between layers and domain-driven testing, programming starts to look like a
//: fundamentally different activity. Instead of focusing on a) superficial,
//: b) local rules on c) code [like say http://blog.bbv.ch/2013/06/05/clean-code-cheat-sheet],
//: we allow programmers to engage with the a) deep, b) global structure of
//: the c) domain. If you can systematically track discontinuities in the
//: domain, you don't care if the code used gotos as long as it passed all
//: scenarios. If scenarios become more robust to run, it becomes easier to
//: try out radically different implementations for the same program. If code
//: is super-easy to rewrite, it becomes less important what indentation style
//: it uses, or that the objects are appropriately encapsulated, or that the
//: functions are referentially transparent.
//:
//: Instead of plumbing, programming becomes building and gradually refining a
//: map of the environment the program must operate under. Whether a program
//: is 'correct' at a given point in time is a red herring; what matters is
//: avoiding regression by monotonically nailing down the more 'eventful'
//: parts of the terrain. It helps readers new and old, and rewards curiosity,
//: to organize large programs in self-similar hierarchies of example scenarios
//: colocated with the code that makes them work.
//:
//:   "Programming properly should be regarded as an activity by which
//:   programmers form a mental model, rather than as production of a program."
//:   -- Peter Naur (http://alistair.cockburn.us/ASD+book+extract%3A+%22Naur,+Ehn,+Musashi%22)

//:: == Core data structures

:(before "End Globals")
trace_stream* Trace_stream = NULL;

:(before "End Types")
struct trace_stream {
  vector<trace_line> past_lines;
  // End trace_stream Fields

  trace_stream() {
    // End trace_stream Constructor
  }
  ~trace_stream() {
    // End trace_stream Destructor
  }
  // End trace_stream Methods
};

//:: == Adding to the trace

//: Top-level method is trace() which can be used like an ostream. Usage:
//:   trace(depth, label) << ... << end();
//: Don't forget the 'end()' to actually append to the trace.
:(before "End Includes")
// No brackets around the expansion so that it prints nothing if Trace_stream
// isn't initialized.
#define trace(...)  !Trace_stream ? cerr : Trace_stream->stream(__VA_ARGS__)

:(before "End trace_stream Fields")
// accumulator for current trace_line
ostringstream* curr_stream;
string curr_label;
int curr_depth;
// other stuff
int collect_depth;  // avoid tracing lower levels for speed
ofstream null_stream;  // never opened, so writes to it silently fail

//: Some constants.
:(before "struct trace_stream")  // include constants in all cleaved compilation units
const int Max_depth = 9999;
:(before "End trace_stream Constructor")
curr_stream = NULL;
curr_depth = Max_depth;
collect_depth = Max_depth;

:(before "struct trace_stream")
struct trace_line {
  string contents;
  string label;
  int depth;  // 0 is 'sea level'; positive integers are progressively 'deeper' and lower level
  trace_line(string c, string l) {
    contents = c;
    label = l;
    depth = 0;
  }
  trace_line(string c, string l, int d) {
    contents = c;
    label = l;
    depth = d;
  }
};

//: Starting a new trace line.
:(before "End trace_stream Methods")
ostream& stream(string label) {
  return stream(Max_depth, label);
}

ostream& stream(int depth, string label) {
  if (depth > collect_depth) return null_stream;
  curr_stream = new ostringstream;
  curr_label = label;
  curr_depth = depth;
  return *curr_stream;
}

//: End of a trace line; append it to the trace.
:(before "End Types")
struct end {};
:(code)
ostream& operator<<(ostream& os, end /*unused*/) {
  if (Trace_stream) Trace_stream->newline();
  return os;
}

:(before "End trace_stream Methods")
void newline();
:(code)
void trace_stream::newline() {
  if (!curr_stream) return;
  string curr_contents = curr_stream->str();
  if (!curr_contents.empty()) {
    past_lines.push_back(trace_line(curr_contents, trim(curr_label), curr_depth));  // preserve indent in contents
    // maybe incrementally dump trace
    trace_line& t = past_lines.back();
    if (should_incrementally_print_trace()) {
      cerr       << std::setw(4) << t.depth << ' ' << t.label << ": " << t.contents << '\n';
    }
    // End trace Commit
  }

  // clean up
  delete curr_stream;
  curr_stream = NULL;
  curr_label.clear();
  curr_depth = Max_depth;
}

//:: == Initializing the trace in scenarios

:(before "End Includes")
#define START_TRACING_UNTIL_END_OF_SCOPE  lease_tracer leased_tracer;
:(before "End Test Setup")
START_TRACING_UNTIL_END_OF_SCOPE

//: Trace_stream is a resource, lease_tracer uses RAII to manage it.
:(before "End Types")
struct lease_tracer {
  lease_tracer();
  ~lease_tracer();
};
:(code)
lease_tracer::lease_tracer() { Trace_stream = new trace_stream; }
lease_tracer::~lease_tracer() {
  delete Trace_stream;
  Trace_stream = NULL;
}

//:: == Errors using traces

:(before "End Includes")
#define raise  (!Trace_stream ? (scroll_to_bottom_and_close_console(),++Trace_errors,cerr) /*do print*/ : Trace_stream->stream(Error_depth, "error"))

//: Print errors to the screen by default.
:(before "struct trace_stream")  // include constants in all cleaved compilation units
const int Error_depth = 0;
:(before "End Globals")
int Hide_errors = false;  // if set, don't print errors to screen
:(before "End Reset")
Hide_errors = false;
:(code)
bool trace_stream::should_incrementally_print_trace() {
  if (!Hide_errors && curr_depth == Error_depth) return true;
  // End Incremental Trace Print Conditions
  return false;
}
:(before "End trace_stream Methods")
bool should_incrementally_print_trace();

:(before "End Globals")
int Trace_errors = 0;  // used only when Trace_stream is NULL

// Fail scenarios that displayed (unexpected) errors.
// Expected errors should always be hidden and silently checked for.
:(before "End Test Teardown")
if (Passed && !Hide_errors && trace_contains_errors()) {
  Passed = false;
}
:(code)
bool trace_contains_errors() {
  return Trace_errors > 0 || trace_count("error") > 0;
}

:(before "End Includes")
// If we aren't yet sure how to deal with some corner case, use assert_for_now
// to indicate that it isn't an inviolable invariant.
#define assert_for_now assert
#define raise_for_now raise

//: Automatically close the console in some situations.
:(before "End One-time Setup")
atexit(scroll_to_bottom_and_close_console);
:(code)
void scroll_to_bottom_and_close_console() {
  if (!tb_is_active()) return;
  // leave the screen in a relatively clean state
  tb_set_cursor(tb_width()-1, tb_height()-1);
  cout << "\r\n";
  tb_shutdown();
}
:(before "End Includes")
#include "termbox/termbox.h"

//:: == Other assertions on traces
//: Primitives:
//:   - CHECK_TRACE_CONTENTS(lines)
//:     Assert that the trace contains the given lines (separated by newlines)
//:     in order. There can be other intervening lines between them.
//:   - CHECK_TRACE_DOESNT_CONTAIN(line)
//:   - CHECK_TRACE_DOESNT_CONTAIN(label, contents)
//:     Assert that the trace doesn't contain the given (single) line.
//:   - CHECK_TRACE_COUNT(label, count)
//:     Assert that the trace contains exactly 'count' lines with the given
//:     'label'.
//:   - CHECK_TRACE_CONTAINS_ERRORS()
//:   - CHECK_TRACE_DOESNT_CONTAIN_ERRORS()
//:   - trace_count_prefix(label, prefix)
//:     Count the number of trace lines with the given 'label' that start with
//:     the given 'prefix'.

:(before "End Includes")
#define CHECK_TRACE_CONTENTS(...)  check_trace_contents(__FUNCTION__, __FILE__, __LINE__, __VA_ARGS__)

#define CHECK_TRACE_DOESNT_CONTAIN(...)  CHECK(trace_doesnt_contain(__VA_ARGS__))

#define CHECK_TRACE_COUNT(label, count) \
  if (Passed && trace_count(label) != (count)) { \
    cerr << "\nF - " << __FUNCTION__ << "(" << __FILE__ << ":" << __LINE__ << "): trace_count of " << label << " should be " << count << '\n'; \
    cerr << "  got " << trace_count(label) << '\n';  /* multiple eval */ \
    DUMP(label); \
    Passed = false; \
    return;  /* Currently we stop at the very first failure. */ \
  }

#define CHECK_TRACE_CONTAINS_ERRORS()  CHECK(trace_contains_errors())
#define CHECK_TRACE_DOESNT_CONTAIN_ERRORS() \
  if (Passed && trace_contains_errors()) { \
    cerr << "\nF - " << __FUNCTION__ << "(" << __FILE__ << ":" << __LINE__ << "): unexpected errors\n"; \
    DUMP("error"); \
    Passed = false; \
    return; \
  }

// Allow scenarios to ignore trace lines generated during setup.
#define CLEAR_TRACE  delete Trace_stream, Trace_stream = new trace_stream

:(code)
bool check_trace_contents(string FUNCTION, string FILE, int LINE, string expected) {
  if (!Passed) return false;
  if (!Trace_stream) return false;
  vector<string> expected_lines = split(expected, "");
  int curr_expected_line = 0;
  while (curr_expected_line < SIZE(expected_lines) && expected_lines.at(curr_expected_line).empty())
    ++curr_expected_line;
  if (curr_expected_line == SIZE(expected_lines)) return true;
  string label, contents;
  split_label_contents(expected_lines.at(curr_expected_line), &label, &contents);
  for (vector<trace_line>::iterator p = Trace_stream->past_lines.begin();  p != Trace_stream->past_lines.end();  ++p) {
    if (label != p->label) continue;
    if (contents != trim(p->contents)) continue;
    ++curr_expected_line;
    while (curr_expected_line < SIZE(expected_lines) && expected_lines.at(curr_expected_line).empty())
      ++curr_expected_line;
    if (curr_expected_line == SIZE(expected_lines)) return true;
    split_label_contents(expected_lines.at(curr_expected_line), &label, &contents);
  }

  if (line_exists_anywhere(label, contents)) {
    cerr << "\nF - " << FUNCTION << "(" << FILE << ":" << LINE << "): line [" << label << ": " << contents << "] out of order in trace:\n";
    DUMP("");
  }
  else {
    cerr << "\nF - " << FUNCTION << "(" << FILE << ":" << LINE << "): missing [" << contents << "] in trace:\n";
    DUMP(label);
  }
  Passed = false;
  return false;
}

bool trace_doesnt_contain(string expected) {
  vector<string> tmp = split_first(expected, ": ");
  if (SIZE(tmp) == 1) {
    raise << expected << ": missing label or contents in trace line\n" << end();
    assert(false);
  }
  return trace_count(tmp.at(0), tmp.at(1)) == 0;
}

int trace_count(string label) {
  return trace_count(label, "");
}

int trace_count(string label, string line) {
  if (!Trace_stream) return 0;
  long result = 0;
  for (vector<trace_line>::iterator p = Trace_stream->past_lines.begin();  p != Trace_stream->past_lines.end();  ++p) {
    if (label == p->label) {
      if (line == "" || trim(line) == trim(p->contents))
        ++result;
    }
  }
  return result;
}

int trace_count_prefix(string label, string prefix) {
  if (!Trace_stream) return 0;
  long result = 0;
  for (vector<trace_line>::iterator p = Trace_stream->past_lines.begin();  p != Trace_stream->past_lines.end();  ++p) {
    if (label == p->label) {
      if (starts_with(trim(p->contents), trim(prefix)))
        ++result;
    }
  }
  return result;
}

void split_label_contents(const string& s, string* label, string* contents) {
  static const string delim(": ");
  size_t pos = s.find(delim);
  if (pos == string::npos) {
    *label = "";
    *contents = trim(s);
  }
  else {
    *label = trim(s.substr(0, pos));
    *contents = trim(s.substr(pos+SIZE(delim)));
  }
}

bool line_exists_anywhere(const string& label, const string& contents) {
  for (vector<trace_line>::iterator p = Trace_stream->past_lines.begin();  p != Trace_stream->past_lines.end();  ++p) {
    if (label != p->label) continue;
    if (contents == trim(p->contents)) return true;
  }
  return false;
}

vector<string> split(string s, string delim) {
  vector<string> result;
  size_t begin=0, end=s.find(delim);
  while (true) {
    if (end == string::npos) {
      result.push_back(string(s, begin, string::npos));
      break;
    }
    result.push_back(string(s, begin, end-begin));
    begin = end+SIZE(delim);
    end = s.find(delim, begin);
  }
  return result;
}

vector<string> split_first(string s, string delim) {
  vector<string> result;
  size_t end=s.find(delim);
  result.push_back(string(s, 0, end));
  if (end != string::npos)
    result.push_back(string(s, end+SIZE(delim), string::npos));
  return result;
}

//:: == Helpers for debugging using traces

:(before "End Includes")
// To debug why a scenario is failing, dump its trace using '?'.
#define DUMP(label)  if (Trace_stream) cerr << Trace_stream->readable_contents(label);

// To add temporary prints to the trace, use 'dbg'.
// `git log` should never show any calls to 'dbg'.
#define dbg trace(0, "a")

//: Dump the entire trace to file where it can be browsed offline.
//: Dump the trace as it happens; that way you get something even if the
//: program crashes.

:(before "End Globals")
ofstream Trace_file;
:(before "End Commandline Options(*arg)")
else if (is_equal(*arg, "--trace")) {
  Trace_stream = new trace_stream;
  cerr << "saving trace to 'last_run'\n";
  Trace_file.open("last_run");
  // Add a dummy line up top; otherwise the `browse_trace` tool currently has
  // no way to expand any lines above an error.
  Trace_file << "   0 dummy: start\n";
}
:(before "End trace Commit")
if (Trace_file) {
  Trace_file << std::setw(4) << t.depth << ' ' << t.label << ": " << t.contents << '\n';
}
:(before "End One-time Setup")
atexit(cleanup_main);
:(code)
void cleanup_main() {
  if (Trace_file) Trace_file.close();
  // End cleanup_main
}

:(before "End trace_stream Methods")
string readable_contents(string label) {
  string trim(const string& s);  // prototype
  ostringstream output;
  label = trim(label);
  for (vector<trace_line>::iterator p = past_lines.begin();  p != past_lines.end();  ++p)
    if (label.empty() || label == p->label)
      output << std::setw(4) << p->depth << ' ' << p->label << ": " << p->contents << '\n';
  return output.str();
}

//: Print traces to the screen as they happen.
//: Particularly useful when juggling multiple trace streams, like when
//: debugging sandboxes.
:(before "End Globals")
bool Dump_trace = false;
:(before "End Commandline Options(*arg)")
else if (is_equal(*arg, "--dump")) {
  Dump_trace = true;
}
:(before "End Incremental Trace Print Conditions")
if (Dump_trace) return true;

//: Miscellaneous helpers.

:(code)
string trim(const string& s) {
  string::const_iterator first = s.begin();
  while (first != s.end() && isspace(*first))
    ++first;
  if (first == s.end()) return "";

  string::const_iterator last = --s.end();
  while (last != s.begin() && isspace(*last))
    --last;
  ++last;
  return string(first, last);
}

:(before "End Includes")
#include <vector>
using std::vector;
#include <list>
using std::list;
#include <set>
using std::set;

#include <sstream>
using std::istringstream;
using std::ostringstream;

#include <fstream>
using std::ifstream;
using std::ofstream;