Andrew Kesterson
9845e77a5c
Closes groups A, C, D, E, F, H and J of TODO.md section 4, plus RESTORE and RENUMBER, and closes section 6 -- all seventeen reference defects. Seven of those turned out to have been fixed or never ported and nobody had written it down; the audit records the evidence for each. Two of the seventeen were real. math_plus mutated its left operand when the operand was mutable, so A# + 1 could modify A#; it was gated on FOR/NEXT coverage because NEXT relied on the mutation, so tests/for_next.c came first and NEXT now writes the counter back itself. And the binary operators summed both numeric fields of their right operand, which no BASIC program can reach -- that one needed a test written against the value API. Writing the tests turned up eight defects nobody had listed. Seven are fixed: IF A = 2 THEN was a parse error; only == worked IF ... AND ... was a parse error, because a condition parsed as one relation IF A = 1 OR B = 2 THEN was silently always false, and so was IF A THEN EXIT before any NEXT restarted the program and exhausted the variable pool READ never found a DATA line above it, and swallowed the lines between PRINT 2 + 2 at the prompt was filed as program text instead of answering a short read discarded its bytes, so COPY produced empty files every verb taking an argument list said "peek() returned nil token!" on none The eighth is not fixed and cannot be quietly: a FOR whose step overshoots runs its body one extra time, and FOR I = 1 TO 1 runs it zero times. The two errors cancel for a step of 1, which is why neither was noticed. Correcting them changes the expected output of a checked-in acceptance file, and tests/reference/README.md forbids editing one to suit this interpreter. It is tests/for_semantics.c in AKBASIC_KNOWN_FAILING_TESTS, asserting the correct contract, and TODO.md items 19 and 20. Sprites are real libakgl actors with a renderfunc of their own, because akgl_actor_render draws every sprite square and an actor has no per-axis scale. Both are filed upstream. SPRSAV takes an image file, an SSHAPE handle or a 63-element integer array -- a string here cannot hold a zero byte. Verbs that need hardware that does not exist are refused by name with the reason rather than faked: SYS, HEADER, COLLECT, BACKUP, BOOT, FILTER, and DIRECTORY, which is refused for a missing libakstdlib wrapper filed upstream. 94 tests in the default build, 93 with SDL, 94 under ASan and UBSan, doxygen clean. The Go acceptance corpus stayed green throughout. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
104 lines
3.7 KiB
C
104 lines
3.7 KiB
C
/**
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* @file for_semantics.c
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* @brief Known-failing. Asserts what FOR/NEXT *should* do, which is not what it does.
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*
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* Registered in `AKBASIC_KNOWN_FAILING_TESTS`, so CTest expects it to fail. When
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* it starts passing, CTest reports "unexpectedly passed" and that is the cue to
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* move it into `AKBASIC_TESTS` along with the fix.
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*
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* Two defects, both found while writing tests/for_next.c and both recorded in
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* TODO.md section 6. Neither is the Go reference's fault alone -- the port
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* reproduced them faithfully -- and neither can be fixed without moving a golden
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* file, which is why they are written down rather than quietly corrected.
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*
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* **1. The body runs once with the overshot value.** The loop condition is
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* tested against the counter *before* the increment, so the increment's result
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* reaches the body before anything checks it against the limit.
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* `FOR I = 1 TO 9 STEP 3` runs its body with 1, 4, 7 and then 10.
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*
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* **2. The counter does not survive the loop.** It lives in the environment the
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* loop pushed, which pops when the loop ends, so reading it afterwards finds a
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* fresh variable holding zero. A C128 leaves the counter at the value that ended
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* the loop, and plenty of published listings read it afterwards.
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*
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* They are related but not the same fix: the first is an ordering bug in
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* akbasic_cmd_next(), and the second is a scoping decision about where a loop
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* counter is created.
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*/
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#include <string.h>
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#include <akbasic/error.h>
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#include <akbasic/runtime.h>
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#include "harness.h"
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#include "testutil.h"
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/** @brief Run a program to completion in RUN mode, from a string. */
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static akerr_ErrorContext AKERR_NOIGNORE *run_program(const char *source)
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{
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PREPARE_ERROR(errctx);
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PASS(errctx, harness_start(NULL));
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PASS(errctx, akbasic_runtime_load(&HARNESS_RUNTIME, source));
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PASS(errctx, akbasic_runtime_start(&HARNESS_RUNTIME, AKBASIC_MODE_RUN));
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PASS(errctx, akbasic_runtime_run(&HARNESS_RUNTIME, 0));
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SUCCEED_RETURN(errctx);
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}
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/** @brief A step that overshoots the limit must not run the body again. */
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static void test_step_does_not_overshoot(void)
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{
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TEST_REQUIRE_OK(run_program("10 FOR I# = 1 TO 9 STEP 3\n"
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"20 PRINT I#\n"
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"30 NEXT I#\n"));
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/* Today: "1\n4\n7\n10\n" -- the body runs with 10, which is past the limit. */
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TEST_REQUIRE_STR(HARNESS_OUTPUT, "1\n4\n7\n");
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harness_stop();
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TEST_REQUIRE_OK(run_program("10 FOR I# = 1 TO 2 STEP 100\n"
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"20 PRINT I#\n"
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"30 NEXT I#\n"));
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/* Today: "1\n101\n". */
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TEST_REQUIRE_STR(HARNESS_OUTPUT, "1\n");
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harness_stop();
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}
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/** @brief The loop counter is readable after the loop, holding where it stopped. */
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static void test_counter_survives_the_loop(void)
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{
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TEST_REQUIRE_OK(run_program("10 FOR I# = 1 TO 4\n"
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"20 NEXT I#\n"
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"30 PRINT I#\n"));
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/* Today: "0\n" -- the loop's environment took the variable with it. */
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TEST_REQUIRE_STR(HARNESS_OUTPUT, "5\n");
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harness_stop();
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}
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/**
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* @brief A loop whose limit equals its start still runs its body once.
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*
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* `FOR I = 1 TO 1` executes the body one time on every BASIC there has ever
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* been. Here the entry test treats "the counter has reached the limit" as
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* "do not enter", so the body is skipped entirely -- and
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* tests/reference/language/flowcontrol/forloopwaitingforcommand.bas pins that,
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* which is why this cannot simply be corrected.
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*/
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static void test_single_iteration_loop(void)
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{
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TEST_REQUIRE_OK(run_program("10 FOR I# = 1 TO 1\n"
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"20 PRINT \"ONCE\"\n"
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"30 NEXT I#\n"));
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/* Today: "" -- the body never runs. */
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TEST_REQUIRE_STR(HARNESS_OUTPUT, "ONCE\n");
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harness_stop();
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}
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int main(void)
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{
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test_step_does_not_overshoot();
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test_counter_survives_the_loop();
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test_single_iteration_loop();
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return akbasic_test_failures;
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}
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