feat: add JSON-RPC client with connection check command

test/noise-rpc-test.el

@@ -0,0 +1,39 @@
+;;; noise-rpc-test.el --- Tests for noise-rpc -*- lexical-binding: t; -*-
+
+(require 'ert)
+(require 'noise-rpc)
+
+(ert-deftest noise-rpc--build-request-no-params ()
+  "Test that noise-rpc--build-request produces valid JSON-RPC 2.0 without params."
+  (let* ((body (noise-rpc--build-request "getVersion"))
+         (parsed (json-parse-string body)))
+    (should (string= "2.0" (gethash "jsonrpc" parsed)))
+    (should (string= "getVersion" (gethash "method" parsed)))
+    (should (integerp (gethash "id" parsed)))
+    (should-not (gethash "params" parsed))))
+
+(ert-deftest noise-rpc--build-request-with-params ()
+  "Test that params are included when provided."
+  (let* ((body (noise-rpc--build-request "sendMessage" :recipient "+123" :message "hi"))
+         (parsed (json-parse-string body)))
+    (should (string= "sendMessage" (gethash "method" parsed)))
+    (let ((params (gethash "params" parsed)))
+      (should params)
+      (should (string= "+123" (gethash "recipient" params)))
+      (should (string= "hi" (gethash "message" params))))))
+
+(ert-deftest noise-rpc--parse-response-success ()
+  "Test parsing a successful JSON-RPC response."
+  (let* ((raw "{\"jsonrpc\":\"2.0\",\"result\":{\"version\":\"0.13.0\"},\"id\":1}")
+         (result (noise-rpc--parse-response raw)))
+    (should result)
+    (should (string= "0.13.0" (gethash "version" result)))))
+
+(ert-deftest noise-rpc--parse-response-error ()
+  "Test parsing a JSON-RPC error raises noise-rpc-error."
+  (let ((raw "{\"jsonrpc\":\"2.0\",\"error\":{\"code\":-32000,\"message\":\"method not found\"},\"id\":1}"))
+    (should-error (noise-rpc--parse-response raw) :type 'noise-rpc-error)))
+
+(ert-deftest noise-rpc--parse-response-malformed ()
+  "Test that malformed JSON raises noise-rpc-error."
+  (should-error (noise-rpc--parse-response "not json") :type 'noise-rpc-error))