// fmttest — exercises lib/fmt's stream sinks (fprint / fprintln).
// Run with `out/bin/ww run lib/fmt/fmttest.ww`.
//
// Each @test writes through a memio.stream and compares the resulting
// bytes against an inline `want` literal. Bodies are short enough that
// the parallel-array idiom used by memiotest doesn't apply — every row
// here threads a different variadic argument-pack into fprint, and the
// variadic shape can't be table-driven within a single fn body.

package fmt_test;

import fmt;
import io;
import memio;
import os;

fn streq(a: str, b: str) bool = {
	if (a.len != b.len) { return false; };
	let i: i32 = 0;
	for (i < a.len) {
		if (a[i] != b[i]) { return false; };
		i += 1;
	};
	return true;
};

// ---- an error-returning stream for the io.error surfacing test --------
//
// Replaces the OLD io.closed source. errvt is module-static; its
// reader/writer return a nomem-widened io.error.
let errvt: io.vtable;

fn errread(s: io.stream, buf: []u8) (size | io.eof | io.error) = {
	let nm: nomem; let e: io.error = nm; return e;
};
fn errwrite(s: io.stream, buf: []u8) (size | io.error) = {
	let nm: nomem; let e: io.error = nm; return e;
};
fn errsource() io.stream = {
	errvt.reader = (&errread):  *io.reader;
	errvt.writer = (&errwrite): *io.writer;
	return &errvt;
};

// ---- fprint: bare str --------------------------------------------------

@test fn fprintbarestr() void = {
	let mem: memio.stream = memio.dynamic();
	let s: io.stream = &mem.vt;

	let r: (size | io.error) = fmt.fprint(s, "hello");
	match (r) {
	case let n: size => { assert(!(n: i32 != 5)); };
	case let eioe: io.error => abort();
	};
	assert(!(!streq(memio.string(&mem), "hello")));

	let c: (void | io.error) = io.close(s);
	match (c) { case void => {}; case let eioe: io.error => abort(); };
};

// ---- fprint: int + str mix, space-separated ----------------------------

@test fn fprintintstr() void = {
	let mem: memio.stream = memio.dynamic();
	let s: io.stream = &mem.vt;

	let r: (size | io.error) = fmt.fprint(s, 42i64, "x");
	match (r) {
	case let n: size => { assert(!(n: i32 != 4)); };	// "42 x"
	case let eioe: io.error => abort();
	};
	assert(!(!streq(memio.string(&mem), "42 x")));

	let c: (void | io.error) = io.close(s);
	match (c) { case void => {}; case let eioe: io.error => abort(); };
};

// ---- fprint: i64::MIN / int MIN whole-magnitude (#67) ------------------
// i64dec used `n = -n` within i64, which wraps at i64::MIN (-MIN == MIN),
// so the digit loop never ran and only the bare '-' was emitted. The fix
// takes the magnitude through math.absi64 into u64. These rows pin the
// boundary value plus a normal negative, zero, and int MIN.

@test fn fprinti64min() void = {
	let mem: memio.stream = memio.dynamic();
	let s: io.stream = &mem.vt;

	let m: i64 = -9223372036854775807i64 - 1i64;
	let r: (size | io.error) = fmt.fprint(s, m);
	match (r) {
	case let n: size => { assert(!(n: i32 != 20)); };
	case let eioe: io.error => abort();
	};
	assert(!(!streq(memio.string(&mem), "-9223372036854775808")));

	let c: (void | io.error) = io.close(s);
	match (c) { case void => {}; case let eioe: io.error => abort(); };
};

@test fn fprintintmin() void = {
	let mem: memio.stream = memio.dynamic();
	let s: io.stream = &mem.vt;

	let m: int = -9223372036854775807 - 1;
	let r: (size | io.error) = fmt.fprint(s, m, -7i64, 0i64);
	match (r) {
	case let n: size => { assert(!(n: i32 != 25)); };	// "-9223372036854775808 -7 0"
	case let eioe: io.error => abort();
	};
	assert(!(!streq(memio.string(&mem), "-9223372036854775808 -7 0")));

	let c: (void | io.error) = io.close(s);
	match (c) { case void => {}; case let eioe: io.error => abort(); };
};

// ---- fprint: bool + rune renders as "true A" --------------------------

@test fn fprintboolrune() void = {
	let mem: memio.stream = memio.dynamic();
	let s: io.stream = &mem.vt;

	let r: (size | io.error) = fmt.fprint(s, true, 'A': rune);
	match (r) {
	case let n: size => { assert(!(n: i32 != 6)); };	// "true A"
	case let eioe: io.error => abort();
	};
	assert(!(!streq(memio.string(&mem), "true A")));

	let c: (void | io.error) = io.close(s);
	match (c) { case void => {}; case let eioe: io.error => abort(); };
};

// ---- fprint: zero args returns 0, no bytes written --------------------

@test fn fprintempty() void = {
	let mem: memio.stream = memio.dynamic();
	let s: io.stream = &mem.vt;

	let r: (size | io.error) = fmt.fprint(s);
	match (r) {
	case let n: size => { assert(!(n: i32 != 0)); };
	case let eioe: io.error => abort();
	};
	assert(!(memio.string(&mem).len != 0));

	let c: (void | io.error) = io.close(s);
	match (c) { case void => {}; case let eioe: io.error => abort(); };
};

// ---- fprintln: multi-arg, trailing '\n' --------------------------------

@test fn fprintlnmulti() void = {
	let mem: memio.stream = memio.dynamic();
	let s: io.stream = &mem.vt;

	let r: (size | io.error) = fmt.fprintln(s, "a", 1i64, false);
	match (r) {
	case let n: size => { assert(!(n: i32 != 10)); };	// "a 1 false\n"
	case let eioe: io.error => abort();
	};
	assert(!(!streq(memio.string(&mem), "a 1 false\n")));

	let c: (void | io.error) = io.close(s);
	match (c) { case void => {}; case let eioe: io.error => abort(); };
};

// ---- fprintln: zero args writes just the newline ----------------------

@test fn fprintlnempty() void = {
	let mem: memio.stream = memio.dynamic();
	let s: io.stream = &mem.vt;

	let r: (size | io.error) = fmt.fprintln(s);
	match (r) {
	case let n: size => { assert(!(n: i32 != 1)); };
	case let eioe: io.error => abort();
	};
	assert(!(!streq(memio.string(&mem), "\n")));

	let c: (void | io.error) = io.close(s);
	match (c) { case void => {}; case let eioe: io.error => abort(); };
};

// ---- fprint over a fixed stream: short writes return partial count ----
// memio.fixedwrite caps each call at the remaining buffer space and
// never closes the stream, so fprint sees a short i32 result, not
// io.error. Verifies the inner-loop arithmetic adds the actual byte
// count rather than the requested length.

@test fn fprintfixedshort() void = {
	let buf: [3]u8;
	let mem: memio.stream = memio.fixed(buf[0:3]);
	let s: io.stream = &mem.vt;

	let r: (size | io.error) = fmt.fprint(s, "hello");
	match (r) {
	case let n: size => { assert(!(n: i32 != 3)); };
	case let eioe: io.error => abort();
	};
	assert(!(!streq(memio.string(&mem), "hel")));

	let c: (void | io.error) = io.close(s);
	match (c) { case void => {}; case let eioe: io.error => abort(); };
};

// ---- fprint over a closed stream surfaces io.error -------------------
// Exercises the early-return arm in fprint's inner match — distinct from
// the short-write path above, which keeps returning i32 from a partial
// accept. Single arm is enough: every formattable case routes errors
// through the same putbytes / io.write wiring.

@test fn fprintclosed() void = {
	let s: io.stream = errsource();

	let r: (size | io.error) = fmt.fprint(s, "x");
	match (r) {
	case let n: size => abort();
	case let eioe: io.error => {};
	};
};

// ---- fprintf scenarios -------------------------------------------------
// Each scenario writes through memio.dynamic and compares bytes against
// an inline `want`. Variadic call-site shape forces one body per shape;
// see the file header.

@test fn fprintf_implicit() void = {
	let mem: memio.stream = memio.dynamic();
	let s: io.stream = &mem.vt;
	let r: (size | io.error) = fmt.fprintf(s, "hello {} {}", "world", 42i64);
	match (r) {
	case let n: size => { assert(!(n: i32 != 14)); };
	case let eioe: io.error => abort();
	};
	assert(!(!streq(memio.string(&mem), "hello world 42")));
	let c: (void | io.error) = io.close(s);
	match (c) { case void => {}; case let eioe: io.error => abort(); };
};

@test fn fprintf_indexed() void = {
	let mem: memio.stream = memio.dynamic();
	let s: io.stream = &mem.vt;
	let r: (size | io.error) = fmt.fprintf(s, "{1} {0} {1}", "hello", "world");
	match (r) {
	case let n: size => { assert(!(n: i32 != 17)); };
	case let eioe: io.error => abort();
	};
	assert(!(!streq(memio.string(&mem), "world hello world")));
	let c: (void | io.error) = io.close(s);
	match (c) { case void => {}; case let eioe: io.error => abort(); };
};

@test fn fprintf_literal_braces() void = {
	let mem: memio.stream = memio.dynamic();
	let s: io.stream = &mem.vt;
	let r: (size | io.error) = fmt.fprintf(s, "{{ {} }}", 1i64);
	match (r) {
	case let n: size => { assert(!(n: i32 != 5)); };
	case let eioe: io.error => abort();
	};
	assert(!(!streq(memio.string(&mem), "{ 1 }")));
	let c: (void | io.error) = io.close(s);
	match (c) { case void => {}; case let eioe: io.error => abort(); };
};

@test fn fprintf_width_right() void = {
	let mem: memio.stream = memio.dynamic();
	let s: io.stream = &mem.vt;
	let r: (size | io.error) = fmt.fprintf(s, "{:5}", 42i64);
	match (r) {
	case let n: size => { assert(!(n: i32 != 5)); };
	case let eioe: io.error => abort();
	};
	assert(!(!streq(memio.string(&mem), "   42")));
	let c: (void | io.error) = io.close(s);
	match (c) { case void => {}; case let eioe: io.error => abort(); };
};

@test fn fprintf_width_left() void = {
	let mem: memio.stream = memio.dynamic();
	let s: io.stream = &mem.vt;
	let r: (size | io.error) = fmt.fprintf(s, "{:-5}", 42i64);
	match (r) {
	case let n: size => { assert(!(n: i32 != 5)); };
	case let eioe: io.error => abort();
	};
	assert(!(!streq(memio.string(&mem), "42   ")));
	let c: (void | io.error) = io.close(s);
	match (c) { case void => {}; case let eioe: io.error => abort(); };
};

@test fn fprintf_width_center() void = {
	let mem: memio.stream = memio.dynamic();
	let s: io.stream = &mem.vt;
	let r: (size | io.error) = fmt.fprintf(s, "{:=5}", "hi");
	match (r) {
	case let n: size => { assert(!(n: i32 != 5)); };
	case let eioe: io.error => abort();
	};
	assert(!(!streq(memio.string(&mem), "  hi ")));
	let c: (void | io.error) = io.close(s);
	match (c) { case void => {}; case let eioe: io.error => abort(); };
};

// ---- fprint: rune args emit full UTF-8, not a truncated byte (#66) -----
// writeone/formatraw's rune arm did `buf[0] = r: u8; putbytes(...,1)`,
// emitting only the low byte (invalid UTF-8 for r > 0x7F). The fix routes
// through utf8.encoderune (ref/hare/fmt/print.ha:84). Edge runes: é (2B),
// € (3B), 😀 (4B), A (1B).

@test fn fprintrune() void = {
	let mem: memio.stream = memio.dynamic();
	let s: io.stream = &mem.vt;

	let r: (size | io.error) = fmt.fprint(s, 233: rune, 0x20AC: rune,
	    0x1F600: rune, 65: rune);
	match (r) {
	case let n: size => { assert(!(n: i32 != 13)); };	// 2+1+3+1+4+1+1
	case let eioe: io.error => abort();
	};
	assert(!(!streq(memio.string(&mem), "é € 😀 A")));

	let c: (void | io.error) = io.close(s);
	match (c) { case void => {}; case let eioe: io.error => abort(); };
};

// rawlen's rune arm hardcoded 1, desyncing width-padding for a multibyte
// rune. With runesz it counts the encoded length: € (3B) in width 5 pads
// to "  €" (2 spaces + 3 bytes = 5).
@test fn fprintf_rune_width() void = {
	let mem: memio.stream = memio.dynamic();
	let s: io.stream = &mem.vt;

	let r: (size | io.error) = fmt.fprintf(s, "{:5}", 0x20AC: rune);
	match (r) {
	case let n: size => { assert(!(n: i32 != 5)); };
	case let eioe: io.error => abort();
	};
	assert(!(!streq(memio.string(&mem), "  €")));

	let c: (void | io.error) = io.close(s);
	match (c) { case void => {}; case let eioe: io.error => abort(); };
};

@test fn fprintf_pad_underscore() void = {
	let mem: memio.stream = memio.dynamic();
	let s: io.stream = &mem.vt;
	let r: (size | io.error) = fmt.fprintf(s, "{:_05}", "hi");
	match (r) {
	case let n: size => { assert(!(n: i32 != 5)); };
	case let eioe: io.error => abort();
	};
	assert(!(!streq(memio.string(&mem), "000hi")));
	let c: (void | io.error) = io.close(s);
	match (c) { case void => {}; case let eioe: io.error => abort(); };
};

@test fn fprintf_base_hex() void = {
	let mem: memio.stream = memio.dynamic();
	let s: io.stream = &mem.vt;
	let r: (size | io.error) = fmt.fprintf(s, "{:x} {:X}", 48879i64, 61453i64);
	match (r) {
	case let n: size => { assert(!(n: i32 != 9)); };
	case let eioe: io.error => abort();
	};
	assert(!(!streq(memio.string(&mem), "beef F00D")));
	let c: (void | io.error) = io.close(s);
	match (c) { case void => {}; case let eioe: io.error => abort(); };
};

@test fn fprintf_base_oct_bin() void = {
	let mem: memio.stream = memio.dynamic();
	let s: io.stream = &mem.vt;
	let r: (size | io.error) = fmt.fprintf(s, "{:o} {:b}", 493i64, 27i64);
	match (r) {
	case let n: size => { assert(!(n: i32 != 9)); };	// "755 11011"
	case let eioe: io.error => abort();
	};
	assert(!(!streq(memio.string(&mem), "755 11011")));
	let c: (void | io.error) = io.close(s);
	match (c) { case void => {}; case let eioe: io.error => abort(); };
};

@test fn fprintf_prec_int() void = {
	let mem: memio.stream = memio.dynamic();
	let s: io.stream = &mem.vt;
	let r: (size | io.error) = fmt.fprintf(s, "{:.5}", 42i64);
	match (r) {
	case let n: size => { assert(!(n: i32 != 5)); };
	case let eioe: io.error => abort();
	};
	assert(!(!streq(memio.string(&mem), "00042")));
	let c: (void | io.error) = io.close(s);
	match (c) { case void => {}; case let eioe: io.error => abort(); };
};

@test fn fprintf_prec_str_trunc() void = {
	let mem: memio.stream = memio.dynamic();
	let s: io.stream = &mem.vt;
	let r: (size | io.error) = fmt.fprintf(s, "{:.3}", "hello");
	match (r) {
	case let n: size => { assert(!(n: i32 != 3)); };
	case let eioe: io.error => abort();
	};
	assert(!(!streq(memio.string(&mem), "hel")));
	let c: (void | io.error) = io.close(s);
	match (c) { case void => {}; case let eioe: io.error => abort(); };
};

@test fn fprintf_sign_neg() void = {
	let mem: memio.stream = memio.dynamic();
	let s: io.stream = &mem.vt;
	let r: (size | io.error) = fmt.fprintf(s, "{} {:+} {: }", -7i64, 7i64, 7i64);
	match (r) {
	case let n: size => { assert(!(n: i32 != 8)); };	// "-7 +7  7"
	case let eioe: io.error => abort();
	};
	assert(!(!streq(memio.string(&mem), "-7 +7  7")));
	let c: (void | io.error) = io.close(s);
	match (c) { case void => {}; case let eioe: io.error => abort(); };
};

@test fn fprintfln_basic() void = {
	let mem: memio.stream = memio.dynamic();
	let s: io.stream = &mem.vt;
	let r: (size | io.error) = fmt.fprintfln(s, "x={}", 9i64);
	match (r) {
	case let n: size => { assert(!(n: i32 != 4)); };	// "x=9\n"
	case let eioe: io.error => abort();
	};
	assert(!(!streq(memio.string(&mem), "x=9\n")));
	let c: (void | io.error) = io.close(s);
	match (c) { case void => {}; case let eioe: io.error => abort(); };
};

@test fn fprintf_closed() void = {
	let s: io.stream = errsource();
	let r: (size | io.error) = fmt.fprintf(s, "hello {}", 1i64);
	match (r) {
	case let n: size => abort();
	case let eioe: io.error => {};
	};
};

@test fn bsprintf_basic() void = {
	let buf: [16]u8;
	let r: (str | io.error) = fmt.bsprintf(buf[0:16], "{} {}", "hi", 42i64);
	match (r) {
	case let s: str => { assert(!(!streq(s, "hi 42"))); };
	case let eioe: io.error => abort();
	};
};

// Positive control: an EXACT-fit render must still succeed — the sink
// fills to the last byte but no write lands on a full sink, so the
// nomem guard (memio.ww:190) must not fire. Guards against the
// truncation fix over-rejecting a render that exactly fits.
@test fn bsprintf_exact() void = {
	let buf: [5]u8;
	let r: (str | io.error) = fmt.bsprintf(buf[0:5], "hello");
	match (r) {
	case let s: str => { assert(!(!streq(s, "hello"))); };
	case let eioe: io.error => abort();
	};
};

// Pins the formatfield bool / rune arms inside fprintf's for-loop —
// the codegen-smell repro shape (task #18). Pre-task-#18, the str arm
// is also exercised by fprintf_implicit; this adds the two remaining
// tagged arms so a future task-#18 fix that re-introduces the 24B
// widen-by-value cannot regress silently.
@test fn fprintf_bool_rune() void = {
	let mem: memio.stream = memio.dynamic();
	let s: io.stream = &mem.vt;
	let r: (size | io.error) = fmt.fprintf(s, "{} {}", true, 'A': rune);
	match (r) {
	case let n: size => { assert(!(n: i32 != 6)); };	// "true A"
	case let eioe: io.error => abort();
	};
	assert(!(!streq(memio.string(&mem), "true A")));
	let c: (void | io.error) = io.close(s);
	match (c) { case void => {}; case let eioe: io.error => abort(); };
};

// Verifies bsprintf's truncation contract — overflowing a fixed sink
// surfaces nomem, not a prefix (memio.fixedwrite returns nomem once
// full, ref/hare/fmt/wrappers.ha:50). Pairs with fprintfixedshort
// above which covers the partial-write (short i32) path.
@test fn bsprintf_trunc() void = {
	let buf: [3]u8;
	let r: (str | io.error) = fmt.bsprintf(buf[0:3], "{} {}", "hi", 42i64);
	match (r) {
	case let s: str => abort();
	case let eioe: io.error => { assert(eioe is nomem); };
	};
};

// Truncation through the width/pad path also surfaces nomem. Buffer
// 3B, target "   42" (5B): the 3 lead pad spaces fill the sink, then
// formatraw writes "42" into the full sink → nomem. Also pins
// formatone's tail-pad counter (the loop must not spin on the full
// sink before the error propagates).
@test fn bsprintf_width_trunc() void = {
	let buf: [3]u8;
	let r: (str | io.error) = fmt.bsprintf(buf[0:3], "{:5}", 42i64);
	match (r) {
	case let s: str => abort();
	case let eioe: io.error => { assert(eioe is nomem); };
	};
};

// Empty-sink discriminator: the cleanest single-write red/green split.
// The first non-empty write to a zero-length sink hits the full-sink
// guard → nomem; pre-fix it returned 0 and bsprintf yielded "" as a
// success.
@test fn bsprintf_empty() void = {
	let buf: [0]u8;
	let r: (str | io.error) = fmt.bsprintf(buf[0:0], "x");
	match (r) {
	case let s: str => abort();
	case let eioe: io.error => { assert(eioe is nomem); };
	};
};

// asprintf — heap-allocated render through memio.dynamic + shrink-to-fit.
// Caller frees via os.free(r.ptr, r.len) when r.len > 0.

@test fn asprintf_basic() void = {
	let r: str = fmt.asprintf("{} {}", "hi", 42i64);
	assert(!(!streq(r, "hi 42")));
	os.free(r.ptr: *void, r.len: u64);
};

// Output > memio.dynamic's initial 8B cap to exercise the
// double-and-copy grow path; 34B target traverses 8→16→32→64.
@test fn asprintf_growth() void = {
	let r: str = fmt.asprintf("hello {} world {} value {}", "alpha", "beta", "gamma");
	assert(!(!streq(r, "hello alpha world beta value gamma")));
	os.free(r.ptr: *void, r.len: u64);
};

// Empty format pins the no-allocation path: memio.dynamic.grow never
// fires (cap stays 0), and the asprintf shrink-to-fit path returns
// {nil, 0} without calling os.alloc. Free is skipped — matches the
// strings.dup empty-input contract.
@test fn asprintf_empty() void = {
	let r: str = fmt.asprintf("");
	assert(!(r.len != 0));
};

// Indexed placeholder + modifier through asprintf — confirms the full
// {n:mods} parser path works through the heap-allocated sink, not just
// the memio.fixed (bsprintf) and memio.dynamic-via-fprintf paths.
@test fn asprintf_indexed_mods() void = {
	let r: str = fmt.asprintf("{1:_05}", "zzz", 42i64);
	assert(!(!streq(r, "00042")));
	os.free(r.ptr: *void, r.len: u64);
};

// ---- f64 dispatch arm -------------------------------------------------
//
// Pins the f64 formattable arm landed under task #17 (unblocked by #30
// — the variant-widen-from-X0 fix). strconv.f64tos drives the render;
// see lib/strconv/strconv.ww for the documented subset (fixed-point,
// 6 fractional digits, trailing-zero trim, magnitudes ≥ 9e18 → "huge",
// no NaN/±Inf detection).
//
// Mods scope under v1: width / alignment / pad / sign mods honored.
// `prec` and `base` ignored — graduate when strconv grows ffmt/fflags.

@test fn fprintf_f64_basic() void = {
	let mem: memio.stream = memio.dynamic();
	let s: io.stream = &mem.vt;
	let r: (size | io.error) = fmt.fprintf(s, "{}", 1.5);
	match (r) {
	case let n: size => { assert(!(n: i32 != 3)); };
	case let eioe: io.error => abort();
	};
	assert(!(!streq(memio.string(&mem), "1.5")));
	let c: (void | io.error) = io.close(s);
	match (c) { case void => {}; case let eioe: io.error => abort(); };
};

@test fn fprintf_f64_int_valued() void = {
	let mem: memio.stream = memio.dynamic();
	let s: io.stream = &mem.vt;
	let r: (size | io.error) = fmt.fprintf(s, "{}", 1.0);
	match (r) {
	case let n: size => { assert(!(n: i32 != 1)); };
	case let eioe: io.error => abort();
	};
	assert(!(!streq(memio.string(&mem), "1")));
	let c: (void | io.error) = io.close(s);
	match (c) { case void => {}; case let eioe: io.error => abort(); };
};

@test fn fprintf_f64_neg() void = {
	let mem: memio.stream = memio.dynamic();
	let s: io.stream = &mem.vt;
	let r: (size | io.error) = fmt.fprintf(s, "{}", -2.5);
	match (r) {
	case let n: size => { assert(!(n: i32 != 4)); };
	case let eioe: io.error => abort();
	};
	assert(!(!streq(memio.string(&mem), "-2.5")));
	let c: (void | io.error) = io.close(s);
	match (c) { case void => {}; case let eioe: io.error => abort(); };
};

@test fn fprintf_f64_zero() void = {
	let mem: memio.stream = memio.dynamic();
	let s: io.stream = &mem.vt;
	let r: (size | io.error) = fmt.fprintf(s, "{}", 0.0);
	match (r) {
	case let n: size => { assert(!(n: i32 != 1)); };
	case let eioe: io.error => abort();
	};
	assert(!(!streq(memio.string(&mem), "0")));
	let c: (void | io.error) = io.close(s);
	match (c) { case void => {}; case let eioe: io.error => abort(); };
};

@test fn fprintf_f64_small_frac() void = {
	let mem: memio.stream = memio.dynamic();
	let s: io.stream = &mem.vt;
	let r: (size | io.error) = fmt.fprintf(s, "{}", 0.05);
	match (r) {
	case let n: size => { assert(!(n: i32 != 4)); };
	case let eioe: io.error => abort();
	};
	assert(!(!streq(memio.string(&mem), "0.05")));
	let c: (void | io.error) = io.close(s);
	match (c) { case void => {}; case let eioe: io.error => abort(); };
};

// Pins a large magnitude through the fmt dispatch — post-Ryū-graduation
// (fold-5) this is scientific notation, not the old lossy "huge" fallback.
// Catches any regression where mods accidentally pre-truncate the view.
@test fn fprintf_f64_huge() void = {
	let mem: memio.stream = memio.dynamic();
	let s: io.stream = &mem.vt;
	let r: (size | io.error) = fmt.fprintf(s, "{}", 9.5e18);
	match (r) {
	case let n: size => { assert(!(n: i32 != 6)); };	// "9.5e18"
	case let eioe: io.error => abort();
	};
	assert(!(!streq(memio.string(&mem), "9.5e18")));
	let c: (void | io.error) = io.close(s);
	match (c) { case void => {}; case let eioe: io.error => abort(); };
};

// Sign-mod fold: '+' on positive, '-' still wins on negative (the
// natural '-' from strconv is peeled and signof reapplies).
@test fn fprintf_f64_sign_plus() void = {
	let mem: memio.stream = memio.dynamic();
	let s: io.stream = &mem.vt;
	let r: (size | io.error) = fmt.fprintf(s, "{:+} {:+}", 1.5, -1.5);
	match (r) {
	case let n: size => { assert(!(n: i32 != 9)); };	// "+1.5 -1.5"
	case let eioe: io.error => abort();
	};
	assert(!(!streq(memio.string(&mem), "+1.5 -1.5")));
	let c: (void | io.error) = io.close(s);
	match (c) { case void => {}; case let eioe: io.error => abort(); };
};

@test fn fprintf_f64_sign_space() void = {
	let mem: memio.stream = memio.dynamic();
	let s: io.stream = &mem.vt;
	let r: (size | io.error) = fmt.fprintf(s, "{: }", 1.5);
	match (r) {
	case let n: size => { assert(!(n: i32 != 4)); };
	case let eioe: io.error => abort();
	};
	assert(!(!streq(memio.string(&mem), " 1.5")));
	let c: (void | io.error) = io.close(s);
	match (c) { case void => {}; case let eioe: io.error => abort(); };
};

// Width + alignment round-trip through rawlenf64 (sign-aware len count).
@test fn fprintf_f64_width_right() void = {
	let mem: memio.stream = memio.dynamic();
	let s: io.stream = &mem.vt;
	let r: (size | io.error) = fmt.fprintf(s, "{:8}", 1.5);
	match (r) {
	case let n: size => { assert(!(n: i32 != 8)); };
	case let eioe: io.error => abort();
	};
	assert(!(!streq(memio.string(&mem), "     1.5")));
	let c: (void | io.error) = io.close(s);
	match (c) { case void => {}; case let eioe: io.error => abort(); };
};

@test fn fprintf_f64_width_left() void = {
	let mem: memio.stream = memio.dynamic();
	let s: io.stream = &mem.vt;
	let r: (size | io.error) = fmt.fprintf(s, "{:-8}", 1.5);
	match (r) {
	case let n: size => { assert(!(n: i32 != 8)); };
	case let eioe: io.error => abort();
	};
	assert(!(!streq(memio.string(&mem), "1.5     ")));
	let c: (void | io.error) = io.close(s);
	match (c) { case void => {}; case let eioe: io.error => abort(); };
};

// Legacy fprint variadic — covers the non-printf surface arm (where
// formatraw isn't reached because there's no mods parser).
@test fn fprint_f64_variadic() void = {
	let mem: memio.stream = memio.dynamic();
	let s: io.stream = &mem.vt;
	let r: (size | io.error) = fmt.fprint(s, 1.5, "x");
	match (r) {
	case let n: size => { assert(!(n: i32 != 5)); };	// "1.5 x"
	case let eioe: io.error => abort();
	};
	assert(!(!streq(memio.string(&mem), "1.5 x")));
	let c: (void | io.error) = io.close(s);
	match (c) { case void => {}; case let eioe: io.error => abort(); };
};

@test fn bsprintf_f64() void = {
	let buf: [16]u8;
	let r: (str | io.error) = fmt.bsprintf(buf[0:16], "x={}", 1.5);
	match (r) {
	case let s: str => { assert(!(!streq(s, "x=1.5"))); };
	case let eioe: io.error => abort();
	};
};

// Heap sink + both signs.
@test fn asprintf_f64() void = {
	let r: str = fmt.asprintf("{} {}", 1.5, -2.5);
	assert(!(!streq(r, "1.5 -2.5")));
	os.free(r.ptr: *void, r.len: u64);
};