Test examples/stdio_server.rb

Including a sanity test ensures that the example code isn't outright
wrong. This is not intended to serve as unit tests for the example
functionality.

Author: sambostock

README.md

@@ -121,6 +121,7 @@ transport.open
 
 You can run this script and then type in requests to the server at the command line.
 
+<!-- SNIPPET ID: running_stdio_server -->
 ```console
 $ ./examples/stdio_server.rb
 {"jsonrpc":"2.0","id":"1","method":"ping"}

test/integration/examples_test.rb

@@ -0,0 +1,56 @@
+# frozen_string_literal: true
+
+require "test_helper"
+
+require "open3"
+require "json"
+require "timeout"
+require "tempfile"
+require "fileutils"
+
+require "readme_test_helper"
+
+# Run tests on the files in the `examples` directory to ensure they work as expected.
+# These are not intended to be comprehensive; they are just sanity checks.
+class ExamplesTest < ActiveSupport::TestCase
+  include ReadmeTestHelper
+
+  make_my_diffs_pretty!
+
+  test "examples/stdio_server.rb example works exactly as documented in README" do
+    command_line, *input_lines = extract_readme_code_snippet("running_stdio_server", language: "console").lines(chomp: true)
+
+    command = command_line.delete_prefix("$ ")
+    stdin_data = input_lines.join("\n")
+
+    stdout, stderr, status = Open3.capture3(command, chdir: project_root, stdin_data:)
+    assert_predicate(status, :success?, "Expected #{command} to exit with success, but got exit status #{status.exitstatus}\n\nSTDOUT: #{stdout}\n\nSTDERR: #{stderr}")
+    assert_empty(stderr, "Expected no stderr in: #{stderr}")
+    refute_empty(stdout, "Expected stdout not to be empty")
+
+    assert_equal(
+      [
+        { jsonrpc: "2.0", id: "1", result: {} },
+        {
+          jsonrpc: "2.0",
+          id: "2",
+          result: {
+            tools: [
+              {
+                name: "example_tool",
+                description: "A simple example tool that adds two numbers",
+                inputSchema: { type: "object", properties: { a: { type: "number" }, b: { type: "number" } }, required: ["a", "b"] },
+              },
+              {
+                name: "echo",
+                description: "A simple example tool that echoes back its arguments",
+                inputSchema: { type: "object", properties: { message: { type: "string" } }, required: ["message"] },
+              },
+            ],
+          },
+        },
+      ],
+      stdout.lines.map { |line| JSON.parse(line, symbolize_names: true) },
+    )
+  end
+end