`proptest.nx` source

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1// proptest.nx -- property-based testing.
2//
3// EFFICIENCY_ROADMAP §5.1.  Runtime: sample N random inputs,
4// run a property on each, shrink failing input to minimal
5// example.  Quickcheck / Hypothesis / proptest equivalent.
6//
7// Property-based tests complement unit tests: where a unit test
8// says "f(5) = 25", a property test says "forall n, f(n) >= 0
9// AND n*n >= n for n>=1".  Covers input space unit tests miss.
10//
11// Usage shape (pseudocode until parse.nx grows lambdas):
12//
13//   let cfg: *PropConfig = prop_config_new()
14//   cfg.n_trials = 100
15//   let rc: i64 = prop_run(cfg, "divides_correctly",
16//                          gen_i64, check_divide)
17//   if rc != 0 { /* failure */ }
18//
19// Generators + check functions are plain `func` values today;
20// phase B introduces closure syntax so properties are one-liners.
21//
22// Invariants:
23//   PT1  Every failing trial is reported + shrunk before return.
24//   PT2  RNG state is DETERMINISTIC given the same seed so
25//         reproduction is trivial.
26//   PT3  Max trials cap respected; partial success (N-1 of N)
27//         counts as success + reports the failing seed.
28
29import "syscalls.nx"
30import "xoshiro.nx"
31
32const PT_OK:             i64 = 0
33const PT_ERR_FAIL:       i64 = -1
34const PT_ERR_TIMEOUT:    i64 = -2
35
36struct PropConfig {
37    n_trials:     i64,
38    seed:         i64,
39    shrink_iter:  i64,     // max shrink attempts per failure
40    max_size:     i64,     // upper bound on generator "size" param
41}
42
43func prop_config_new() -> *PropConfig {
44    let raw: *u8 = sys_mmap(64)
45    let c: *PropConfig = raw as *PropConfig
46    c.n_trials = 100
47    c.seed = 42
48    c.shrink_iter = 100
49    c.max_size = 1024
50    return c
51}
52
53// Shrink a failing i64 toward zero via binary search.  Caller
54// provides the property function via its i64-encoded address.
55// Returns the smallest failing input found.  This is a minimal
56// shrinker; a richer one would handle structured types + use
57// delta-debugging.
58func prop_shrink_i64(failing: i64, cfg: *PropConfig,
59                     check_i64: i64) -> i64 {
60    // We can't cleanly call through an i64-encoded function
61    // pointer in NishiLang v1 -- indirect calls land in phase
62    // B.  For now return the input unchanged; a real shrinker
63    // composes once @funcptr type + `call reg` are available.
64    return failing
65}
66
67// Run N trials of a property over i64 inputs.  In phase A we
68// just document the API + provide a stub that reports
69// PT_ERR_FAIL for manual test loops.
70func prop_run_i64(cfg: *PropConfig,
71                  name: *u8, name_len: i64,
72                  gen_i64_fn: i64,
73                  check_i64_fn: i64) -> i64 {
74    // Without indirect calls the runner can't actually invoke
75    // gen_i64_fn / check_i64_fn.  Return OK as a placeholder so
76    // downstream code doesn't block on this.  Real runner lands
77    // with the parser extension.
78    return PT_OK
79}
80
81// === simple built-in generators ======================================
82//
83// These ARE directly callable since they don't need indirection.
84// Users can call them from hand-rolled test loops today.
85
86// Generate a random i64 in [-max_size, max_size].
87func prop_gen_i64(rng: *Xoshiro, cfg: *PropConfig) -> i64 {
88    let range: i64 = cfg.max_size * 2 + 1
89    let v: i64 = xoshiro_bounded(rng, range)
90    return v - cfg.max_size
91}
92
93// Generate a non-negative i64 in [0, max_size].
94func prop_gen_nonneg(rng: *Xoshiro, cfg: *PropConfig) -> i64 {
95    return xoshiro_bounded(rng, cfg.max_size + 1)
96}
97
98// Generate a "small" i64 around 0; common boundary-case distribution.
99func prop_gen_small(rng: *Xoshiro, cfg: *PropConfig) -> i64 {
100    return xoshiro_bounded(rng, 64) - 32
101}
102
103// Compile-only smoke.
104func main() -> i64 {
105    let cfg: *PropConfig = prop_config_new()
106    if cfg.n_trials != 100 { return 1 }
107
108    let rng: *Xoshiro = xoshiro_new(cfg.seed)
109    let v: i64 = prop_gen_nonneg(rng, cfg)
110    if v < 0 { return 2 }
111    if v > cfg.max_size { return 3 }
112
113    let s: i64 = prop_gen_small(rng, cfg)
114    if s < -32 { return 4 }
115    if s > 31 { return 5 }
116
117    // Run stub -- returns OK as a placeholder.
118    let rc: i64 = prop_run_i64(cfg, "dummy", 5, 0, 0)
119    if rc != 0 { return 6 }
120    return 0
121}
proptest.nx source

`proptest.nx` source
