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Diffstat (limited to 'transect/003trace.cc')
| -rw-r--r-- | transect/003trace.cc | 408 |
1 files changed, 0 insertions, 408 deletions
diff --git a/transect/003trace.cc b/transect/003trace.cc deleted file mode 100644 index 3b4ae596..00000000 --- a/transect/003trace.cc +++ /dev/null @@ -1,408 +0,0 @@ -//: 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* testing. -//: We focus on the domain of inputs the whole program needs to handle rather -//: than the correctness of individual functions. All tests 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; -//: -//: Tests 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 tests 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 tests 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 tests, 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 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 the tests. If -//: tests 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) - -:(before "End Types") -struct trace_line { - int depth; // optional field just to help browse traces later - string label; - string contents; - trace_line(string l, string c) :depth(0), label(l), contents(c) {} - trace_line(int d, string l, string c) :depth(d), label(l), contents(c) {} -}; - -//: Support for tracing an entire run. -//: Traces can have a lot of overhead, so only turn them on when asked. -:(before "End Commandline Options(*arg)") -else if (is_equal(*arg, "--trace")) { - Save_trace = true; -} -:(before "End Commandline Parsing") -if (Save_trace) { - cerr << "initializing trace\n"; - Trace_stream = new trace_stream; -} -:(code) -void cleanup_main() { - if (!Trace_stream) return; - if (Save_trace) - Trace_stream->save(); - delete Trace_stream; - Trace_stream = NULL; -} -:(before "End One-time Setup") -atexit(cleanup_main); - -:(before "End Types") -// Pre-define some global constants that trace_stream needs to know about. -// Since they're in the Types section, they'll be included in any cleaved -// compilation units. So no extern linkage. -const int Max_depth = 9999; -const int Error_depth = 0; // definitely always print errors - -struct trace_stream { - vector<trace_line> past_lines; - // accumulator for current line - ostringstream* curr_stream; - string curr_label; - int curr_depth; - int collect_depth; - ofstream null_stream; // never opens a file, so writes silently fail - trace_stream() :curr_stream(NULL), curr_depth(Max_depth), collect_depth(Max_depth) {} - ~trace_stream() { if (curr_stream) delete curr_stream; } - - 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; - (*curr_stream) << std::hex; - return *curr_stream; - } - - void save() { - cerr << "saving trace to 'last_run'\n"; - ofstream fout("last_run"); - fout << readable_contents(""); - fout.close(); - } - - // be sure to call this before messing with curr_stream or curr_label - void newline(); - // useful for debugging - string readable_contents(string label); // empty label = show everything -}; - -:(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_depth, trim(curr_label), curr_contents)); // preserve indent in contents - if ((!Hide_errors && curr_depth == Error_depth) - || Dump_trace - || (!Dump_label.empty() && curr_label == Dump_label)) - cerr << curr_label << ": " << curr_contents << '\n'; - } - delete curr_stream; - curr_stream = NULL; - curr_label.clear(); - curr_depth = Max_depth; -} - -string trace_stream::readable_contents(string label) { - 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(); -} - -:(before "End Globals") -trace_stream* Trace_stream = NULL; -int Trace_errors = 0; // used only when Trace_stream is NULL - -:(before "End Globals") -bool Hide_errors = false; // if set, don't print even error trace lines to screen -bool Dump_trace = false; // if set, print trace lines to screen -string Dump_label = ""; // if set, print trace lines matching a single label to screen -:(before "End Reset") -Hide_errors = false; -Dump_trace = false; // toggle this to print traces to screen as they are emitted -Dump_label = ""; - -:(before "End Includes") -#define CLEAR_TRACE delete Trace_stream, Trace_stream = new trace_stream; - -// Top-level helper. IMPORTANT: can't nest -#define trace(...) !Trace_stream ? cerr /*print nothing*/ : Trace_stream->stream(__VA_ARGS__) - -// Just for debugging; 'git log' should never show any calls to 'dbg'. -#define dbg trace(0, "a") -#define DUMP(label) if (Trace_stream) cerr << Trace_stream->readable_contents(label); - -// Errors are a special layer. -#define raise (!Trace_stream ? (++Trace_errors,cerr) /*do print*/ : Trace_stream->stream(Error_depth, "error")) -// 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 - -// Inside tests, fail any tests that displayed (unexpected) errors. -// Expected errors in tests 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 Types") -struct end {}; -:(code) -ostream& operator<<(ostream& os, end /*unused*/) { - if (Trace_stream) Trace_stream->newline(); - return os; -} - -:(before "End Globals") -bool Save_trace = false; // if set, write out trace to disk - -// 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() { - if (Save_trace) Trace_stream->save(); - delete Trace_stream, Trace_stream = NULL; -} -:(before "End Includes") -#define START_TRACING_UNTIL_END_OF_SCOPE lease_tracer leased_tracer; -:(before "End Test Setup") -START_TRACING_UNTIL_END_OF_SCOPE - -:(before "End Includes") -#define CHECK_TRACE_CONTENTS(...) check_trace_contents(__FUNCTION__, __FILE__, __LINE__, __VA_ARGS__) - -#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; \ - } - -#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_DOESNT_CONTAIN(...) CHECK(trace_doesnt_contain(__VA_ARGS__)) - -:(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; -} - -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; -} - -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; -} - -bool trace_doesnt_contain(string label, string line) { - return trace_count(label, line) == 0; -} - -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_doesnt_contain(tmp.at(0), tmp.at(1)); -} - -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; -} - -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; |