Add failing test for #1231.

tests/Baseline/spicy.types.unit.synchronize-on-gap/output

@@ -0,0 +1,20 @@
+### BTest baseline data generated by btest-diff. Do not edit. Use "btest -U/-u" to update. Requires BTest >= 0.63.
+[spicy-verbose] - state: type=sync::Xs input="A<gap>..." stream=0xXXXXXXXX offsets=0/0/1027 chunks=3 frozen=no mode=default trim=yes lah=n/a lah_token="n/a" recovering=no
+[spicy-verbose] - parsing production: Unit: sync_Xs -> xs
+[spicy] sync::Xs
+[spicy-verbose]   - state: type=sync::Xs input="A<gap>..." stream=0xXXXXXXXX offsets=0/0/1027 chunks=3 frozen=no mode=default trim=no lah=n/a lah_token="n/a" recovering=no
+[spicy-verbose]   - parsing production: While: xs  -> while(<look-ahead-found>): anon
+[spicy-verbose]     - state: type=sync::Xs input="A<gap>..." stream=0xXXXXXXXX offsets=0/0/1027 chunks=3 frozen=no mode=default trim=no lah=1 lah_token="A" recovering=no
+[spicy-verbose]     - state: type=sync::Xs input="A<gap>..." stream=0xXXXXXXXX offsets=0/0/1027 chunks=3 frozen=no mode=default trim=no lah=1 lah_token="A" recovering=no
+[spicy-verbose]     - parsing production: Ctor: anon -> /(A|B|C)/ (regexp) (container 'xs')
+[spicy-verbose]       - consuming look-ahead token
+[spicy-verbose]     - got container item
+[spicy]   failed to parse list element, will try to synchronize at next possible element
+[spicy-verbose]     - state: type=sync::Xs input="<gap>..." stream=0xXXXXXXXX offsets=0/1/1027 chunks=3 frozen=no mode=default trim=no lah=n/a lah_token="n/a" recovering=yes
+[spicy-verbose]     - state: type=sync::Xs input="C" stream=0xXXXXXXXX offsets=0/1026/1027 chunks=3 frozen=no mode=default trim=no lah=1 lah_token="C" recovering=yes
+[spicy-verbose]     - state: type=sync::Xs input="C" stream=0xXXXXXXXX offsets=0/1026/1027 chunks=3 frozen=no mode=default trim=no lah=1 lah_token="C" recovering=no
+[spicy-verbose]     - parsing production: Ctor: anon -> /(A|B|C)/ (regexp) (container 'xs')
+[spicy-verbose]       - consuming look-ahead token
+[spicy-verbose]     - got container item
+[spicy-verbose]     suspending to wait for more input for stream 0xXXXXXXXX, currently have 0
+[$xs=[b"A", b"C"]]

tests/spicy/types/unit/synchronize-on-gap.test

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+# @TEST-DOC: Validates that if a gap is encountered during recovery we can still resynchronize.
+#
+# @TEST-EXEC: spicyc -cdo sync.cc sync.spicy
+# @TEST-EXEC: spicyc -ldo sync-linker.cc sync.spicy
+# @TEST-EXEC: spicyc -Pdo sync.h sync.spicy
+# @TEST-EXEC: $(spicy-config --cxx-launcher --cxx) -o main main.cc sync.cc sync-linker.cc $(spicy-config --debug --cxxflags --ldflags)
+# @TEST-EXEC: HILTI_DEBUG=spicy:spicy-verbose ./main >output 2>&1
+# @TEST-EXEC: TEST_DIFF_CANONIFIER=${SCRIPTS}/canonify-spicy-debug btest-diff output
+
+# @TEST-START-FILE sync.spicy
+module sync;
+
+public type Xs = unit {
+        xs: (/(A|B|C)/ &synchronize)[];
+        on %synced { confirm; }
+};
+# @TEST-END-FILE
+
+# @TEST-START-FILE main.cc
+#include <hilti/rt/libhilti.h>
+
+#include "sync.h"
+
+int main() {
+    hilti::rt::init();
+
+    auto xs = hilti::rt::reference::make_value<__hlt::sync::Xs>();
+
+    hilti::rt::ValueReference<hilti::rt::Stream> stream;
+    stream->append("A");
+    stream->append(nullptr, 1024); // Gap.
+    stream->append("BC");
+
+    hlt::sync::Xs::parse2(xs, stream, {}, {});
+    std::cout << xs << '\n';
+
+    hilti::rt::done();
+}
+# @TEST-END-FILE