1 //: The goal of layers is to make programs more easy to understand and more
  2 //: malleable, easy to rewrite in radical ways without accidentally breaking
  3 //: some corner case. Tests further both goals. They help understandability by
  4 //: letting one make small changes and get feedback. What if I wrote this line
  5 //: like so? What if I removed this function call, is it really necessary?
  6 //: Just try it, see if the tests pass. Want to explore rewriting this bit in
  7 //: this way? Tests put many refactorings on a firmer footing.
  8 //:
  9 //: But the usual way we write tests seems incomplete. Refactorings tend to
 10 //: work in the small, but don't help with changes to function boundaries. If
 11 //: you want to extract a new function you have to manually test-drive it to
 12 //: create tests for it. If you want to inline a function its tests are no
 13 //: longer valid. In both cases you end up having to reorganize code as well as
 14 //: tests, an error-prone activity.
 15 //:
 16 //: In response, this layer introduces the notion of *domain-driven* testing.
 17 //: We focus on the domain of inputs the whole program needs to handle rather
 18 //: than the correctness of individual functions. All tests invoke the program
 19 //: in a single way: by calling run() with some input. As the program operates
 20 //: on the input, it traces out a list of _facts_ deduced about the domain:
 21 //:   trace("label") << "fact 1: " << val;
 22 //:
 23 //: Tests can now check these facts:
 24 //:   :(scenario foo)
 25 //:   34  # call run() with this input
 26 //:   +label: fact 1: 34  # 'run' should have deduced this fact
 27 //:   -label: fact 1: 35  # the trace should not contain such a fact
 28 //:
 29 //: Since we never call anything but the run() function directly, we never have
 30 //: to rewrite the tests when we reorganize the internals of the program. We
 31 //: just have to make sure our rewrite deduces the same facts about the domain,
 32 //: and that's something we're going to have to do anyway.
 33 //:
 34 //: To avoid the combinatorial explosion of integration tests, each layer
 35 //: mainly logs facts to the trace with a common *label*. All tests in a layer
 36 //: tend to check facts with this label. Validating the facts logged with a
 37 //: specific label is like calling functions of that layer directly.
 38 //:
 39 //: To build robust tests, trace facts about your domain rather than details of
 40 //: how you computed them.
 41 //:
 42 //: More details: http://akkartik.name/blog/tracing-tests
 43 //:
 44 //: ---
 45 //:
 46 //: Between layers and domain-driven testing, programming starts to look like a
 47 //: fundamentally different activity. Instead of a) superficial, b) local rules
 48 //: on c) code [like say http://blog.bbv.ch/2013/06/05/clean-code-cheat-sheet],
 49 //: we allow programmers to engage with the a) deep, b) global structure of the
 50 //: c) domain. If you can systematically track discontinuities in the domain,
 51 //: you don't care if the code used gotos as long as it passed the tests. If
 52 //: tests become more robust to run it becomes easier to try out radically
 53 //: different implementations for the same program. If code is super-easy to
 54 //: rewrite, it becomes less important what indentation style it uses, or that
 55 //: the objects are appropriately encapsulated, or that the functions are
 56 //: referentially transparent.
 57 //:
 58 //: Instead of plumbing, programming becomes building and gradually refining a
 59 //: map of the environment the program must operate under. Whether a program is
 60 //: 'correct' at a given point in time is a red herring; what matters is
 61 //: avoiding regression by monotonically nailing down the more 'eventful' parts
 62 //: of the terrain. It helps readers new and old, and rewards curiosity, to
 63 //: organize large programs in self-similar hierarchies of example scenarios
 64 //: colocated with the code that makes them work.
 65 //:
 66 //:   "Programming properly should be regarded as an activity by which
 67 //:   programmers form a mental model, rather than as production of a program."
 68 //:   -- Peter Naur (http://alistair.cockburn.us/ASD+book+extract%3A+%22Naur,+Ehn,+Musashi%22)
 69 
 70 :(before "End Types")
 71 struct trace_line {
 72   int depth;  // optional field just to help browse traces later
 73   string label;
 74   string contents;
 75   trace_line(string l, string c) :depth(0), label(l), contents(c) {}
 76   trace_line(int d, string l, string c) :depth(d), label(l), contents(c) {}
 77 };
 78 
 79 //: Support for tracing an entire run.
 80 //: Traces can have a lot of overhead, so only turn them on when asked.
 81 :(before "End Commandline Options(*arg)")
 82 else if (is_equal(*arg, "--trace")) {
 83   Save_trace = true;
 84 }
 85 :(before "End Commandline Parsing")
 86 if (Save_trace) {
 87   cerr << "initializing trace\n";
 88   Trace_stream = new trace_stream;
 89 }
 90 :(code)
 91 void cleanup_main() {
 92   if (!Trace_stream) return;
 93   if (Save_trace)
 94     Trace_stream->save();
 95   delete Trace_stream;
 96   Trace_stream = NULL;
 97 }
 98 :(before "End One-time Setup")
 99 atexit(cleanup_main);
100 
101 :(before "End Types")
102 // Pre-define some global constants that trace_stream needs to know about.
103 // Since they're in the Types section, they'll be included in any cleaved
104 // compilation units. So no extern linkage.
105 const int Max_depth = 9999;
106 const int Error_depth = 0;  // definitely always print errors
107 const int App_depth = 2;  // temporarily where all Mu code will trace to
108 
109 struct trace_stream {
110   vector<trace_line> past_lines;
111   // accumulator for current line
112   ostringstream* curr_stream;
113   string curr_label;
114   int curr_depth;
115   int callstack_depth;
116   int collect_depth;
117   ofstream null_stream;  // never opens a file, so writes silently fail
118   trace_stream() :curr_stream(NULL), curr_depth(Max_depth), callstack_depth(0), collect_depth(Max_depth) {}
119   ~trace_stream() { if (curr_stream) delete curr_stream; }
120 
121   ostream& stream(string label) {
122     return stream(Max_depth, label);
123   }
124 
125   ostream& stream(int depth, string label) {
126     if (depth > collect_depth) return null_stream;
127     curr_stream = new ostringstream;
128     curr_label = label;
129     curr_depth = depth;
130     return *curr_stream;
131   }
132 
133   void save() {
134     cerr << "saving trace to 'last_run'\n";
135     ofstream fout("last_run");
136     fout << readable_contents("");
137     fout.close();
138   }
139 
140   // be sure to call this before messing with curr_stream or curr_label
141   void newline();
142   // useful for debugging
143   string readable_contents(string label);  // empty label = show everything
144 };
145 
146 :(code)
147 void trace_stream::newline() {
148   if (!curr_stream) return;
149   string curr_contents = curr_stream->str();
150   if (!curr_contents.empty()) {
151     past_lines.push_back(trace_line(curr_depth, trim(curr_label), curr_contents));  // preserve indent in contents
152     if ((!Hide_errors && curr_label == "error")
153         || Dump_trace
154         || (!Dump_label.empty() && curr_label == Dump_label))
155       cerr << curr_label << ": " << curr_contents << '\n';
156   }
157   delete curr_stream;
158   curr_stream = NULL;
159   curr_label.clear();
160   curr_depth = Max_depth;
161 }
162 
163 string trace_stream::readable_contents(string label) {
164   ostringstream output;
165   label = trim(label);
166   for (vector<trace_line>::iterator p = past_lines.begin();  p != past_lines.end();  ++p)
167     if (label.empty() || label == p->label)
168       output << std::setw(4) << p->depth << ' ' << p->label << ": " << p->contents << '\n';
169   return output.str();
170 }
171 
172 :(before "End Globals")
173 trace_stream* Trace_stream = NULL;
174 int Trace_errors = 0;  // used only when Trace_stream is NULL
175 
176 :(before "End Globals")
177 bool Hide_errors = false;  // if set, don't print even error trace lines to screen
178 bool Dump_trace = false;  // if set, print trace lines to screen
179 string Dump_label = "";  // if set, print trace lines matching a single label to screen
180 :(before "End Reset")
181 Hide_errors = false;
182 Dump_trace = false;  // toggle this to print traces to screen as they are emitted
183 Dump_label = "";
184 
185 :(before "End Includes")
186 #define CLEAR_TRACE  delete Trace_stream, Trace_stream = new trace_stream;
187 
188 // Top-level helper. IMPORTANT: can't nest
189 #define trace(...)  !Trace_stream ? cerr /*print nothing*/ : Trace_stream->stream(__VA_ARGS__)
190 
191 // Just for debugging; 'git log' should never show any calls to 'dbg'.
192 #define dbg trace(0, "a")
193 #define DUMP(label)  if (Trace_stream) cerr << Trace_stream->readable_contents(label);
194 
195 // Errors are a special layer.
196 #define raise  (!Trace_stream ? (scroll_to_bottom_and_close_console(),++Trace_errors,cerr) /*do print*/ : Trace_stream->stream(Error_depth, "error"))
197 // If we aren't yet sure how to deal with some corner case, use assert_for_now
198 // to indicate that it isn't an inviolable invariant.
199 #define assert_for_now assert
200 
201 //: Automatically close the console in some situations.
202 :(before "End One-time Setup")
203 atexit(scroll_to_bottom_and_close_console);
204 :(code)
205 void scroll_to_bottom_and_close_console() {
206   if (!tb_is_active()) return;
207   // leave the screen in a relatively clean state
208   tb_set_cursor(tb_width()-1, tb_height()-1);
209   cout << "\r\n";
210   tb_shutdown();
211 }
212 
213 // Inside tests, fail any tests that displayed (unexpected) errors.
214 // Expected errors in tests should always be hidden and silently checked for.
215 :(before "End Test Teardown")
216 if (Passed && !Hide_errors && trace_contains_errors()) {
217   Passed = false;
218 }
219 :(code)
220 bool trace_contains_errors() {
221   return Trace_errors > 0 || trace_count("error") > 0;
222 }
223 
224 :(before "End Types")
225 struct end {};
226 :(code)
227 ostream& operator<<(ostream& os, end /*unused*/) {
228   if (Trace_stream) Trace_stream->newline();
229   return os;
230 }
231 
232 :(before "End Globals")
233 bool Save_trace = false;  // if set, write out trace to disk
234 
235 // Trace_stream is a resource, lease_tracer uses RAII to manage it.
236 :(before "End Types")
237 struct lease_tracer {
238   lease_tracer();
239   ~lease_tracer();
240 };
241 :(code)
242 lease_tracer::lease_tracer() { Trace_stream = new trace_stream; }
243 lease_tracer::~lease_tracer() {
244   if (Save_trace) Trace_stream->save();
245   delete Trace_stream, Trace_stream = NULL;
246 }
247 :(before "End Includes")
248 #define START_TRACING_UNTIL_END_OF_SCOPE  lease_tracer leased_tracer;
249 :(before "End Test Setup")
250 START_TRACING_UNTIL_END_OF_SCOPE
251 
252 :(before "End Includes")
253 #define CHECK_TRACE_CONTENTS(...)  check_trace_contents(__FUNCTION__, __FILE__, __LINE__, __VA_ARGS__)
254 
255 #define CHECK_TRACE_CONTAINS_ERRORS()  CHECK(trace_contains_errors())
256 #define CHECK_TRACE_DOESNT_CONTAIN_ERRORS() \
257   if (Passed && trace_contains_errors()) { \
258     cerr << "\nF - " << __FUNCTION__ << "(" << __FILE__ << ":" << __LINE__ << "): unexpected errors\n"; \
259     DUMP("error"); \
260     Passed = false; \
261     return; \
262   }
263 
264 #define CHECK_TRACE_COUNT(label, count) \
265   if (Passed && trace_count(label) != (count)) { \
266     cerr << "\nF - " << __FUNCTION__ << "(" << __FILE__ << ":" << __LINE__ << "): trace_count of " << label << " should be " << count << '\n'; \
267     cerr << "  got " << trace_count(label) << '\n';  /* multiple eval */ \
268     DUMP(label); \
269     Passed = false; \
270     return;  /* Currently we stop at the very first failure. */ \
271   }
272 
273 #define CHECK_TRACE_DOESNT_CONTAIN(...)  CHECK(trace_doesnt_contain(__VA_ARGS__))
274 
275 :(code)
276 bool check_trace_contents(string FUNCTION, string FILE, int LINE, string expected) {
277   if (!Passed) return false;
278   if (!Trace_stream) return false;
279   vector<string> expected_lines = split(expected, "^D");
280   int curr_expected_line = 0;
281   while<
# new data structure: a slice is an open interval of addresses [start, end)
# that includes 'start' but not 'end'

== code
#   instruction                     effective address                                                   register    displacement    immediate
# . op          subop               mod             rm32          base        index         scale       r32
# . 1-3 bytes   3 bits              2 bits          3 bits        3 bits      3 bits        2 bits      2 bits      0/1/2/4 bytes   0/1/2/4 bytes

slice-empty?:  # s: (addr slice) -> result/eax: boolean
    # . prologue
    55/push-ebp
    89/copy                         3/mod/direct    5/rm32/ebp    .           .             .           4/r32/esp   .               .                 # copy esp to ebp
    # . save registers
    51/push-ecx
    # ecx = s
    8b/copy                         1/mod/*+disp8   5/rm32/ebp    .           .             .           1/r32/ecx   8/disp8         .                 # copy *(ebp+8) to ecx
    # if (s->start >= s->end) return true
    # . eax = s->start
    8b/copy                         0/mod/indirect  1/rm32/ecx    .           .             .           0/r32/eax   .               .                 # copy *ecx to eax
    # . if (eax >= s->end) return true
    3b/compare                      1/mod/*+disp8   1/rm32/ecx    .           .             .           0/r32/eax   4/disp8         .                 # compare eax with *(ecx+4)
    b8/copy-to-eax  1/imm32/true
    73/jump-if-addr>=  $slice-empty?:end/disp8
    b8/copy-to-eax  0/imm32/false
$slice-empty?:end:
    # . restore registers
    59/pop-to-ecx
    # . epilogue
    89/copy                         3/mod/direct    4/rm32/esp    .           .             .           5/r32/ebp   .               .                 # copy ebp to esp
    5d/pop-to-ebp
    c3/return

test-slice-empty-true:
    # . prologue
    55/push-ebp
    89/copy                         3/mod/direct    5/rm32/ebp    .           .             .           4/r32/esp   .               .                 # copy esp to ebp
    # var slice/ecx: slice = {34, 34}
    68/push  34/imm32/end
    68/push  34/imm32/start
    89/copy                         3/mod/direct    1/rm32/ecx    .           .             .           4/r32/esp   .               .                 # copy esp to ecx
    # slice-empty?(slice)
    # . . push args
    51/push-ecx
    # . . call
    e8/call  slice-empty?/disp32
    # . . discard args
    81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               4/imm32           # add to esp
    # check-ints-equal(eax, 1, msg)
    # . . push args
    68/push  "F - test-slice-empty-true"/imm32
    68/push  1/imm32
    50/push-eax
    # . . call
    e8/call  check-ints-equal/disp32
    # . . discard args
    81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               0xc/imm32         # add to esp
    # . epilogue
    89/copy                         3/mod/direct    4/rm32/esp    .           .             .           5/r32/ebp   .               .                 # copy ebp to esp
    5d/pop-to-ebp
    c3/return

test-slice-empty-false:
    # . prologue
    55/push-ebp
    89/copy                         3/mod/direct    5/rm32/ebp    .           .             .           4/r32/esp   .               .                 # copy esp to ebp
    # var slice/ecx: slice = {32, 34}
    68/push  34/imm32/end
    68/push  32/imm32/start
    89/copy                         3/mod/direct    1/rm32/ecx    .           .             .           4/r32/esp   .               .                 # copy esp to ecx
    # slice-empty?(slice)
    # . . push args
    51/push-ecx
    # . . call
    e8/call  slice-empty?/disp32
    # . . discard args
    81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               4/imm32           # add to esp
    # check-ints-equal(eax, 0, msg)
    # . . push args
    68/push  "F - test-slice-empty-false"/imm32
    68/push  0/imm32
    50/push-eax
    # . . call
    e8/call  check-ints-equal/disp32
    # . . discard args
    81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               0xc/imm32         # add to esp
    # . epilogue
    89/copy                         3/mod/direct    4/rm32/esp    .           .             .           5/r32/ebp   .               .                 # copy ebp to esp
    5d/pop-to-ebp
    c3/return

test-slice-empty-if-start-greater-than-end:
    # . prologue
    55/push-ebp
    89/copy                         3/mod/direct    5/rm32/ebp    .           .             .           4/r32/esp   .               .                 # copy esp to ebp
    # var slice/ecx: slice = {34, 32}
    68/push  32/imm32/end
    68/push  34/imm32/start
    89/copy                         3/mod/direct    1/rm32/ecx    .           .             .           4/r32/esp   .               .                 # copy esp to ecx
    # slice-empty?(slice)
    # . . push args
    51/push-ecx
    # . . call
    e8/call  slice-empty?/disp32
    # . . discard args
    81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               4/imm32           # add to esp
    # check-ints-equal(eax, 1, msg)
    # . . push args
    68/push  "F - test-slice-empty-if-start-greater-than-end"/imm32
    68/push  1/imm32
    50/push-eax
    # . . call
    e8/call  check-ints-equal/disp32
    # . . discard args
    81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               0xc/imm32         # add to esp
    # . epilogue
    89/copy                         3/mod/direct    4/rm32/esp    .           .             .           5/r32/ebp   .               .                 # copy ebp to esp
    5d/pop-to-ebp
    c3/return

slice-equal?:  # s: (addr slice), p: (addr array byte) -> result/eax: boolean
    # pseudocode:
    #   if (p == 0) return (s == 0)
    #   currs = s->start
    #   maxs = s->end
    #   if (maxs - currs != p->size) return false
    #   currp = p->data
    #   while currs < maxs
    #     if (*currs != *currp) return false
    #     ++currs
    #     ++currp
    #   return true
    #
    # registers:
    #   currs: edx
    #   maxs: esi
    #   currp: ebx
    #   *currs: eax
    #   *currp: ecx
    #
    # . prologue
    55/push-ebp
    89/copy                         3/mod/direct    5/rm32/ebp    .           .             .           4/r32/esp   .               .                 # copy esp to ebp
    # . save registers
    51/push-ecx
    52/push-edx
    53/push-ebx
    56/push-esi
    # esi = s
    8b/copy                         1/mod/*+disp8   5/rm32/ebp    .           .             .           6/r32/esi   8/disp8         .                 # copy *(ebp+8) to esi
    # var currs/edx: (addr byte) = s->start
    8b/copy                         0/mod/indirect  6/rm32/esi    .           .             .           2/r32/edx   .               .                 # copy *esi to edx
    # var maxs/esi: (addr byte) = s->end
    8b/copy                         1/mod/*+disp8   6/rm32/esi    .           .             .           6/r32/esi   4/disp8         .                 # copy *(esi+4) to esi
    # var ssize/eax: int = maxs - currs
    89/copy                         3/mod/direct    0/rm32/eax    .           .             .           6/r32/esi   .               .                 # copy esi to eax
    29/subtract                     3/mod/direct    0/rm32/eax    .           .             .           2/r32/edx   .               .                 # subtract edx from eax
    # ebx = p
    8b/copy                         1/mod/*+disp8   5/rm32/ebp    .           .             .           3/r32/ebx   0xc/disp8       .                 # copy *(ebp+12) to ebx
    # if (p != 0) goto next check
    81          7/subop/compare     3/mod/direct    3/rm32/ebx    .           .             .           .           .               0/imm32           # compare ebx
    75/jump-if-!=  $slice-equal?:nonnull-string/disp8
$slice-equal?:null-string:
    # return s->start == s->end
    3d/compare-eax-and  0/imm32
    74/jump-if-=  $slice-equal?:true/disp8
    eb/jump  $slice-equal?:false/disp8
$slice-equal?:nonnull-string:
    # if (ssize != p->size) return false
    39/compare                      0/mod/indirect  3/rm32/ebx    .           .             .           0/r32/eax   .               .                 # compare *ebx and eax
    75/jump-if-!=  $slice-equal?:false/disp8
    # var currp/ebx: (addr byte) = p->data
    81          0/subop/add         3/mod/direct    3/rm32/ebx    .           .             .           .           .               4/imm32           # add to ebx
    # var c1/eax: byte = 0
    31/xor                          3/mod/direct    0/rm32/eax    .           .             .           0/r32/eax   .               .                 # clear eax
    # var c2/ecx: byte = 0
    31/xor                          3/mod/direct    1/rm32/ecx    .           .             .           1/r32/ecx   .               .                 # clear ecx
$slice-equal?:loop:
    # if (currs >= maxs) return true
    39/compare                      3/mod/direct    2/rm32/edx    .           .             .           6/r32/esi   .               .                 # compare edx with esi
    73/jump-if-addr>=  $slice-equal?:true/disp8
    # c1 = *currp
    8a/copy-byte                    0/mod/indirect  3/rm32/ebx    .           .             .           0/r32/AL    .               .                 # copy byte at *ebx to AL
    # c2 = *currs
    8a/copy-byte                    0/mod/indirect  2/rm32/edx    .           .             .           1/r32/CL    .               .                 # copy byte at *edx to CL
    # if (c1 != c2) return false
    39/compare                      3/mod/direct    0/rm32/eax    .           .             .           1/r32/ecx   .               .                 # compare eax and ecx
    75/jump-if-!=  $slice-equal?:false/disp8
    # ++currp
    43/increment-ebx
    # ++currs
    42/increment-edx
    eb/jump $slice-equal?:loop/disp8
$slice-equal?:false:
    b8/copy-to-eax  0/imm32
    eb/jump  $slice-equal?:end/disp8
$slice-equal?:true:
    b8/copy-to-eax  1/imm32
$slice-equal?:end:
    # . restore registers
    5e/pop-to-esi
    5b/pop-to-ebx
    5a/pop-to-edx
    59/pop-to-ecx
    # . epilogue
    89/copy                         3/mod/direct    4/rm32/esp    .           .             .           5/r32/ebp   .               .                 # copy ebp to esp
    5d/pop-to-ebp
    c3/return

test-slice-equal:
    # - slice-equal?(slice("Abc"), "Abc") == 1
    # . prologue
    55/push-ebp
    89/copy                         3/mod/direct    5/rm32/ebp    .           .             .           4/r32/esp   .               .                 # copy esp to ebp
    # (eax..ecx) = "Abc"
    b8/copy-to-eax  "Abc"/imm32
    8b/copy                         0/mod/indirect  0/rm32/eax    .           .             .           1/r32/ecx   .               .                 # copy *eax to ecx
    8d/copy-address                 1/mod/*+disp8   4/rm32/sib    0/base/eax  1/index/ecx   .           1/r32/ecx   4/disp8         .                 # copy eax+ecx+4 to ecx
    05/add-to-eax  4/imm32
    # var slice/ecx: slice = {eax, ecx}
    51/push-ecx
    50/push-eax
    89/copy                         3/mod/direct    1/rm32/ecx    .           .             .           4/r32/esp   .               .                 # copy esp to ecx
    # eax = slice-equal?(ecx, "Abc")
    # . . push args
    68/push  "Abc"/imm32
    51/push-ecx
    # . . call
    e8/call  slice-equal?/disp32
    # . . discard args
    81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               8/imm32           # add to esp
    # check-ints-equal(eax, 1, msg)
    # . . push args
    68/push  "F - test-slice-equal"/imm32
    68/push  1/imm32
    50/push-eax
    # . . call
    e8/call  check-ints-equal/disp32
    # . . discard args
    81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               0xc/imm32         # add to esp
    # . epilogue
    89/copy                         3/mod/direct    4/rm32/esp    .           .             .           5/r32/ebp   .               .                 # copy ebp to esp
    5d/pop-to-ebp
    c3/return

test-slice-equal-false:
    # - slice-equal?(slice("bcd"), "Abc") == 0
    # . prologue
    55/push-ebp
    89/copy                         3/mod/direct    5/rm32/ebp    .           .             .           4/r32/esp   .               .                 # copy esp to ebp
    # (eax..ecx) = "bcd"
    b8/copy-to-eax  "bcd"/imm32
    8b/copy                         0/mod/indirect  0/rm32/eax    .           .             .           1/r32/ecx   .               .                 # copy *eax to ecx
    8d/copy-address                 1/mod/*+disp8   4/rm32/sib    0/base/eax  1/index/ecx   .           1/r32/ecx   4/disp8         .                 # copy eax+ecx+4 to ecx
    05/add-to-eax  4/imm32
    # var slice/ecx: slice = {eax, ecx}
    51/push-ecx
    50/push-eax
    89/copy                         3/mod/direct    1/rm32/ecx    .           .             .           4/r32/esp   .               .                 # copy esp to ecx
    # eax = slice-equal?(ecx, "Abc")
    # . . push args
    68/push  "Abc"/imm32
    51/push-ecx
    # . . call
    e8/call  slice-equal?/disp32
    # . . discard args
    81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               8/imm32           # add to esp
    # check-ints-equal(eax, 0, msg)
    # . . push args
    68/push  "F - test-slice-equal-false"/imm32
    68/push  0/imm32
    50/push-eax
    # . . call
    e8/call  check-ints-equal/disp32
    # . . discard args
    81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               0xc/imm32         # add to esp
    # . epilogue
    89/copy                         3/mod/direct    4/rm32/esp    .           .             .           5/r32/ebp   .               .                 # copy ebp to esp
    5d/pop-to-ebp
    c3/return

test-slice-equal-too-long:
    # - slice-equal?(slice("Abcd"), "Abc") == 0
    # . prologue
    55/push-ebp
    89/copy                         3/mod/direct    5/rm32/ebp    .           .             .           4/r32/esp   .               .                 # copy esp to ebp
    # (eax..ecx) = "Abcd"
    b8/copy-to-eax  "Abcd"/imm32
    8b/copy                         0/mod/indirect  0/rm32/eax    .           .             .           1/r32/ecx   .               .                 # copy *eax to ecx
    8d/copy-address                 1/mod/*+disp8   4/rm32/sib    0/base/eax  1/index/ecx   .           1/r32/ecx   4/disp8         .                 # copy eax+ecx+4 to ecx
    05/add-to-eax  4/imm32
    # var slice/ecx: slice = {eax, ecx}
    51/push-ecx
    50/push-eax
    89/copy                         3/mod/direct    1/rm32/ecx    .           .             .           4/r32/esp   .               .                 # copy esp to ecx
    # eax = slice-equal?(ecx, "Abc")
    # . . push args
    68/push  "Abc"/imm32
    51/push-ecx
    # . . call
    e8/call  slice-equal?/disp32
    # . . discard args
    81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               8/imm32           # add to esp
    # check-ints-equal(eax, 0, msg)
    # . . push args
    68/push  "F - test-slice-equal-too-long"/imm32
    68/push  0/imm32
    50/push-eax
    # . . call
    e8/call  check-ints-equal/disp32
    # . . discard args
    81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               0xc/imm32         # add to esp
    # . epilogue
    89/copy                         3/mod/direct    4/rm32/esp    .           .             .           5/r32/ebp   .               .                 # copy ebp to esp
    5d/pop-to-ebp
    c3/return

test-slice-equal-too-short:
    # - slice-equal?(slice("A"), "Abc") == 0
    # . prologue
    55/push-ebp
    89/copy                         3/mod/direct    5/rm32/ebp    .           .             .           4/r32/esp   .               .                 # copy esp to ebp
    # (eax..ecx) = "A"
    b8/copy-to-eax  "A"/imm32
    8b/copy                         0/mod/indirect  0/rm32/eax    .           .             .           1/r32/ecx   .               .                 # copy *eax to ecx
    8d/copy-address                 1/mod/*+disp8   4/rm32/sib    0/base/eax  1/index/ecx   .           1/r32/ecx   4/disp8         .                 # copy eax+ecx+4 to ecx
    05/add-to-eax  4/imm32
    # var slice/ecx: slice = {eax, ecx}
    51/push-ecx
    50/push-eax
    89/copy                         3/mod/direct    1/rm32/ecx    .           .             .           4/r32/esp   .               .                 # copy esp to ecx
    # eax = slice-equal?(ecx, "Abc")
    # . . push args
    68/push  "Abc"/imm32
    51/push-ecx
    # . . call
    e8/call  slice-equal?/disp32
    # . . discard args
    81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               8/imm32           # add to esp
    # check-ints-equal(eax, 0, msg)
    # . . push args
    68/push  "F - test-slice-equal-too-short"/imm32
    68/push  0/imm32
    50/push-eax
    # . . call
    e8/call  check-ints-equal/disp32
    # . . discard args
    81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               0xc/imm32         # add to esp
    # . epilogue
    89/copy                         3/mod/direct    4/rm32/esp    .           .             .           5/r32/ebp   .               .                 # copy ebp to esp
    5d/pop-to-ebp
    c3/return

test-slice-equal-empty:
    # - slice-equal?(slice(""), "Abc") == 0
    # . prologue
    55/push-ebp
    89/copy                         3/mod/direct    5/rm32/ebp    .           .             .           4/r32/esp   .               .                 # copy esp to ebp
    # var slice/ecx: slice
    68/push  0/imm32/end
    68/push  0/imm32/start
    89/copy                         3/mod/direct    1/rm32/ecx    .           .             .           4/r32/esp   .               .                 # copy esp to ecx
    # eax = slice-equal?(ecx, "Abc")
    # . . push args
    68/push  "Abc"/imm32
    51/push-ecx
    # . . call
    e8/call  slice-equal?/disp32
    # . . discard args
    81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               8/imm32           # add to esp
    # check-ints-equal(eax, 0, msg)
    # . . push args
    68/push  "F - test-slice-equal-empty"/imm32
    68/push  0/imm32
    50/push-eax
    # . . call
    e8/call  check-ints-equal/disp32
    # . . discard args
    81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               0xc/imm32         # add to esp
    # . epilogue
    89/copy                         3/mod/direct    4/rm32/esp    .           .             .           5/r32/ebp   .               .                 # copy ebp to esp
    5d/pop-to-ebp
    c3/return

test-slice-equal-with-empty:
    # - slice-equal?(slice("Ab"), "") == 0
    # . prologue
    55/push-ebp
    89/copy                         3/mod/direct    5/rm32/ebp    .           .             .           4/r32/esp   .               .                 # copy esp to ebp
    # (eax..ecx) = "Ab"
    b8/copy-to-eax  "Ab"/imm32
    8b/copy                         0/mod/indirect  0/rm32/eax    .           .             .           1/r32/ecx   .               .                 # copy *eax to ecx
    8d/copy-address                 1/mod/*+disp8   4/rm32/sib    0/base/eax  1/index/ecx   .           1/r32/ecx   4/disp8         .                 # copy eax+ecx+4 to ecx
    05/add-to-eax  4/imm32
    # var slice/ecx: slice = {eax, ecx}
    51/push-ecx
    50/push-eax
    89/copy                         3/mod/direct    1/rm32/ecx    .           .             .           4/r32/esp   .               .                 # copy esp to ecx
    # eax = slice-equal?(ecx, "")
    # . . push args
    68/push  ""/imm32
    51/push-ecx
    # . . call
    e8/call  slice-equal?/disp32
    # . . discard args
    81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               8/imm32           # add to esp
    # check-ints-equal(eax, 0, msg)
    # . . push args
    68/push  "F - test-slice-equal-with-empty"/imm32
    68/push  0/imm32
    50/push-eax
    # . . call
    e8/call  check-ints-equal/disp32
    # . . discard args
    81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               0xc/imm32         # add to esp
    # . epilogue
    89/copy                         3/mod/direct    4/rm32/esp    .           .             .           5/r32/ebp   .               .                 # copy ebp to esp
    5d/pop-to-ebp
    c3/return

test-slice-equal-empty-with-empty:
    # - slice-equal?(slice(""), "") == 1
    # . prologue
    55/push-ebp
    89/copy                         3/mod/direct    5/rm32/ebp    .           .             .           4/r32/esp   .               .                 # copy esp to ebp
    # var slice/ecx: slice
    68/push  0/imm32/end
    68/push  0/imm32/start
    89/copy                         3/mod/direct    1/rm32/ecx    .           .             .           4/r32/esp   .               .                 # copy esp to ecx
    # eax = slice-equal?(ecx, "")
    # . . push args
    68/push  ""/imm32
    51/push-ecx
    # . . call
    e8/call  slice-equal?/disp32
    # . . discard args
    81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               8/i