fix(nim-bindings): add all-endpoints test and fix installation_name ABI

Add nim-bindings/tests/test_all_endpoints.nim which imports bindings
directly and calls every FFI proc, forcing the linker to include all
symbols. This catches link-time and runtime issues that the pingpong
example missed because unused symbols were optimised out.

Running the new test revealed an ABI mismatch in installation_name:
the Rust function used an explicit out-parameter but ReprCString has
only flat fields, so Nim emits it as a C return value.

CI now runs nimble test instead of nimble pingpong.

Author: osmaczko

.github/workflows/ci.yml

@@ -52,5 +52,5 @@ jobs:
           echo "$HOME/.nimble/bin" >> $GITHUB_PATH
       - run: nimble install -dy
         working-directory: nim-bindings
-      - run: nimble pingpong
+      - run: nimble test
         working-directory: nim-bindings

conversations/src/api.rs

@@ -56,11 +56,9 @@ pub fn create_context(name: repr_c::String) -> repr_c::Box<ContextHandle> {
 
 /// Returns the friendly name of the contexts installation.
 ///
-/// # ABI note
-/// The result is written through `out` (Nim's calling convention for large struct returns).
 #[ffi_export]
-pub fn installation_name(ctx: &ContextHandle, out: &mut repr_c::String) {
-    *out = ctx.0.installation_name().to_string().into();
+pub fn installation_name(ctx: &ContextHandle) -> repr_c::String {
+    ctx.0.installation_name().to_string().into()
 }
 
 /// Destroys a conversation store and frees its memory
@@ -74,6 +72,17 @@ pub fn destroy_context(ctx: repr_c::Box<ContextHandle>) {
     drop(ctx);
 }
 
+/// Destroys a repr_c::String and frees its memory
+///
+/// # Safety
+/// - s must be a valid pointer from an FFI function that returns repr_c::String
+/// - s must not be used after this call
+/// - s must not be freed twice
+#[ffi_export]
+pub fn destroy_string(s: repr_c::String) {
+    drop(s);
+}
+
 /// Creates an intro bundle for sharing with other users
 ///
 /// # Returns

nim-bindings/conversations_example.nimble nim-bindings/bindings.nimblenim-bindings/conversations_example.nimble renamed to nim-bindings/bindings.nimble

@@ -24,3 +24,7 @@ before build:
 task pingpong, "Run pingpong example":
   buildRust()
   exec "nim c -r --path:src --passL:../target/release/liblibchat.a --passL:-lm examples/pingpong.nim"
+
+task test, "Run comprehensive all-endpoints test":
+  buildRust()
+  exec "nim c -r --path:src --passL:../target/release/liblibchat.a --passL:-lm tests/test_all_endpoints.nim"

nim-bindings/src/bindings.nim

@@ -84,6 +84,11 @@ proc installation_name*(ctx: ContextHandle): ReprCString {.importc.}
 ## - handle must not be used after this call
 proc destroy_context*(ctx: ContextHandle) {.importc.}
 
+## Free a ReprCString returned by any of the FFI functions
+## - s must be a valid pointer from an FFI function that returns repr_c::String
+## - s must not be used after this call
+proc destroy_string*(s: var ReprCString) {.importc.}
+
 ## Creates an intro bundle for sharing with other users
 ## Returns: CreateIntroResult struct - check error_code field (0 = success, negative = error)
 ## The result must be freed with destroy_intro_result()

nim-bindings/src/libchat.nim

@@ -24,7 +24,8 @@ proc newConversationsContext*(name: string): LibChat =
 proc getInstallationName*(ctx: LibChat): string =
   if ctx.handle == nil:
     return ""
-  let name = installation_name(ctx.handle)
+  var name = installation_name(ctx.handle)
+  defer: destroy_string(name)
   result = $name
 
 ## Destroy the context and free resources

nim-bindings/tests/test_all_endpoints.nim

@@ -0,0 +1,258 @@
+# Comprehensive test for all FFI procs declared in bindings.nim.
+#
+# Design intent: By importing `bindings` directly and calling every importc
+# proc at least once, the linker is forced to include ALL symbol references.
+# This prevents link-time optimizations from stripping unused symbols and
+# catches both link-time crashes (missing symbols) and runtime crashes
+# (wrong ABI, segfaults on use).
+
+import bindings
+
+# ---------------------------------------------------------------------------
+# Assertion helper
+# ---------------------------------------------------------------------------
+
+proc check(cond: bool, msg: string) =
+  if not cond:
+    echo "FAIL: ", msg
+    quit(1)
+  echo "OK:   ", msg
+
+# ---------------------------------------------------------------------------
+# Section 1: Helper proc coverage
+# ---------------------------------------------------------------------------
+
+proc testHelperProcs() =
+  echo "\n--- testHelperProcs ---"
+
+  # toSlice(string) — non-empty and empty branches
+  let s = "hello"
+  let sl = toSlice(s)
+  check(sl.len == 5, "toSlice(string): correct len")
+  check(sl.`ptr` != nil, "toSlice(non-empty string): non-nil ptr")
+
+  let emptySl = toSlice("")
+  check(emptySl.len == 0, "toSlice(empty string): len == 0")
+  check(emptySl.`ptr` == nil, "toSlice(empty string): ptr == nil")
+
+  # toSlice(seq[byte]) — non-empty and empty branches
+  let b: seq[byte] = @[0x61'u8, 0x62'u8, 0x63'u8]
+  let bSl = toSlice(b)
+  check(bSl.len == 3, "toSlice(seq[byte]): correct len")
+  check(bSl.`ptr` != nil, "toSlice(non-empty seq[byte]): non-nil ptr")
+
+  let emptyBSl = toSlice(newSeq[byte](0))
+  check(emptyBSl.len == 0, "toSlice(empty seq[byte]): len == 0")
+  check(emptyBSl.`ptr` == nil, "toSlice(empty seq[byte]): ptr == nil")
+
+  # toReprCString(string) and $(ReprCString) round-trip
+  let name = "testname"
+  let rcs = toReprCString(name)
+  check(rcs.len == csize_t(name.len), "toReprCString: correct len")
+  check(rcs.cap == 0, "toReprCString: cap == 0 (prevents Rust dealloc of Nim memory)")
+  check(rcs.`ptr` != nil, "toReprCString: non-nil ptr")
+  check($rcs == name, "$(ReprCString): round-trips to original string")
+
+  let emptyRcs = toReprCString("")
+  check(emptyRcs.len == 0, "toReprCString(empty): len == 0")
+  check($emptyRcs == "", "$(empty ReprCString): returns empty string")
+
+  # toBytes(string)
+  let bs = toBytes("abc")
+  check(bs.len == 3, "toBytes: correct length")
+  check(bs[0] == 0x61'u8, "toBytes: correct first byte")
+
+  let emptyBs = toBytes("")
+  check(emptyBs.len == 0, "toBytes(empty): empty seq")
+
+# ---------------------------------------------------------------------------
+# Section 2: create_context / installation_name / destroy_context
+# ---------------------------------------------------------------------------
+
+proc testContextLifecycle() =
+  echo "\n--- testContextLifecycle ---"
+
+  let ctx = create_context(toReprCString("lifecycle-test"))
+  check(ctx != nil, "create_context: returns non-nil handle")
+
+  var iname = installation_name(ctx)
+  defer: destroy_string(iname)
+  let inameStr = $iname
+  check(inameStr.len > 0, "installation_name: returns non-empty name")
+  echo "  installation name: ", inameStr
+
+  destroy_context(ctx)
+  echo "  destroy_context: no crash"
+
+# ---------------------------------------------------------------------------
+# Section 3: Full two-party conversation flow
+# ---------------------------------------------------------------------------
+# Exercises: create_intro_bundle, create_new_private_convo, handle_payload,
+# send_content, and all four destroy_* procs.
+# VecPayload helpers ([], len, items) are also exercised here.
+
+proc testFullConversationFlow() =
+  echo "\n--- testFullConversationFlow ---"
+
+  let aliceCtx = create_context(toReprCString("alice"))
+  check(aliceCtx != nil, "Alice: create_context non-nil")
+
+  let bobCtx = create_context(toReprCString("bob"))
+  check(bobCtx != nil, "Bob: create_context non-nil")
+
+  # --- create_intro_bundle ---
+  var bobIntroRes = create_intro_bundle(bobCtx)
+  check(bobIntroRes.error_code == ErrNone,
+        "create_intro_bundle: error_code == ErrNone")
+  check(bobIntroRes.intro_bytes.len > 0,
+        "create_intro_bundle: intro_bytes non-empty")
+
+  # toSeq(VecUint8)
+  let introBytes = toSeq(bobIntroRes.intro_bytes)
+  check(introBytes.len > 0, "toSeq(VecUint8): produces non-empty seq")
+
+  # destroy_intro_result
+  destroy_intro_result(bobIntroRes)
+  echo "  destroy_intro_result: no crash"
+
+  # --- create_new_private_convo ---
+  var convoRes = create_new_private_convo(
+    aliceCtx,
+    toSlice(introBytes),
+    toSlice("Hello, Bob!")
+  )
+  check(convoRes.error_code == ErrNone,
+        "create_new_private_convo: error_code == ErrNone")
+
+  let aliceConvoId = $convoRes.convo_id
+  check(aliceConvoId.len > 0, "create_new_private_convo: convo_id non-empty")
+  echo "  Alice-Bob convo_id: ", aliceConvoId
+
+  # len(VecPayload)
+  let numPayloads = len(convoRes.payloads)
+  check(numPayloads > 0, "len(VecPayload): > 0 payloads in new convo")
+
+  # [](VecPayload, int): subscript access
+  let firstPayload = convoRes.payloads[0]
+  check(firstPayload.data.len > 0, "VecPayload[0].data: non-empty")
+  check(firstPayload.address.len > 0, "VecPayload[0].address: non-empty")
+  echo "  first payload address: ", $firstPayload.address
+
+  # items(VecPayload): collect bytes before destroy
+  var payloadDatas: seq[seq[byte]] = @[]
+  var iterCount = 0
+  for p in convoRes.payloads:
+    payloadDatas.add(toSeq(p.data))
+    inc iterCount
+  check(iterCount == numPayloads,
+        "items(VecPayload): iterator yields all payloads")
+
+  # destroy_convo_result
+  destroy_convo_result(convoRes)
+  echo "  destroy_convo_result: no crash"
+
+  # --- handle_payload ---
+  var bobSawContent = false
+  var bobConvoId = ""
+  for pData in payloadDatas:
+    var hp = handle_payload(bobCtx, toSlice(pData))
+    check(hp.error_code == ErrNone, "handle_payload: error_code == ErrNone")
+
+    let content = toSeq(hp.content)
+    if content.len > 0:
+      bobConvoId = $hp.convo_id
+      check(bobConvoId.len > 0,
+            "handle_payload: convo_id non-empty when content present")
+      if not bobSawContent:
+        check(hp.is_new_convo,
+              "handle_payload: is_new_convo == true on first contact")
+      bobSawContent = true
+      echo "  Bob received content in convo: ", bobConvoId
+
+    destroy_handle_payload_result(hp)
+
+  check(bobSawContent, "handle_payload: Bob received Alice's opening message")
+  echo "  destroy_handle_payload_result: no crash"
+
+  # --- send_content ---
+  var sendRes = send_content(
+    aliceCtx,
+    toReprCString(aliceConvoId),
+    toSlice("How are you, Bob?")
+  )
+  check(sendRes.error_code == ErrNone,
+        "send_content: error_code == ErrNone for valid convo_id")
+  check(len(sendRes.payloads) > 0,
+        "send_content: returns at least one payload")
+
+  var sendPayloadDatas: seq[seq[byte]] = @[]
+  for p in sendRes.payloads:
+    sendPayloadDatas.add(toSeq(p.data))
+
+  # destroy_send_content_result
+  destroy_send_content_result(sendRes)
+  echo "  destroy_send_content_result: no crash"
+
+  # Bob handles follow-up payloads
+  for pData in sendPayloadDatas:
+    var hp2 = handle_payload(bobCtx, toSlice(pData))
+    check(hp2.error_code == ErrNone,
+          "handle_payload: Bob handles send_content payload without error")
+    destroy_handle_payload_result(hp2)
+
+  destroy_context(aliceCtx)
+  destroy_context(bobCtx)
+  echo "  both contexts destroyed: no crash"
+
+# ---------------------------------------------------------------------------
+# Section 4: Error-case coverage
+# ---------------------------------------------------------------------------
+# Exercises destroy_* on error results (empty/null Vecs) to confirm they
+# do not crash.
+
+proc testErrorCases() =
+  echo "\n--- testErrorCases ---"
+
+  let ctx = create_context(toReprCString("error-tester"))
+  check(ctx != nil, "error-tester: create_context non-nil")
+
+  # send_content with a nonexistent convo_id must fail
+  var badSend = send_content(
+    ctx,
+    toReprCString("00000000-0000-0000-0000-nonexistent"),
+    toSlice("payload")
+  )
+  check(badSend.error_code != ErrNone,
+        "send_content(bad convo_id): error_code != ErrNone")
+  echo "  send_content(bad convo_id) error_code: ", badSend.error_code
+  # Destroy error result to confirm destroy handles empty VecPayload
+  destroy_send_content_result(badSend)
+  echo "  destroy_send_content_result(error result): no crash"
+
+  # create_new_private_convo with garbage bytes must fail with ErrBadIntro
+  let badIntro: seq[byte] = @[0xDE'u8, 0xAD'u8, 0xBE'u8, 0xEF'u8]
+  var badConvo = create_new_private_convo(
+    ctx,
+    toSlice(badIntro),
+    toSlice("content")
+  )
+  check(badConvo.error_code == ErrBadIntro,
+        "create_new_private_convo(bad intro): error_code == ErrBadIntro")
+  destroy_convo_result(badConvo)
+  echo "  destroy_convo_result(error result): no crash"
+
+  destroy_context(ctx)
+
+# ---------------------------------------------------------------------------
+# Entry point
+# ---------------------------------------------------------------------------
+
+when isMainModule:
+  echo "=== test_all_endpoints: begin ==="
+
+  testHelperProcs()
+  testContextLifecycle()
+  testFullConversationFlow()
+  testErrorCases()
+
+  echo "\n=== ALL TESTS PASSED ==="