Merge pull request #482 from koic/elicitation_enum_schema

Add `MCP::Elicitation::EnumSchema` builders for SEP-1330

test/mcp/elicitation/enum_schema_test.rb

@@ -0,0 +1,143 @@
+# frozen_string_literal: true
+
+require "test_helper"
+
+module MCP
+  module Elicitation
+    class EnumSchemaTest < ActiveSupport::TestCase
+      test "untitled_single_select returns string + enum schema" do
+        schema = EnumSchema.untitled_single_select(values: ["red", "green", "blue"])
+
+        assert_equal({ type: "string", enum: ["red", "green", "blue"] }, schema.to_h)
+      end
+
+      test "untitled_single_select preserves default value" do
+        schema = EnumSchema.untitled_single_select(values: ["red", "green"], default: "red")
+
+        assert_equal "red", schema.to_h[:default]
+      end
+
+      test "titled_single_select returns string + oneOf schema" do
+        schema = EnumSchema.titled_single_select(
+          options: [
+            { value: "small", title: "Small" },
+            { value: "large", title: "Large" },
+          ],
+        )
+
+        assert_equal(
+          {
+            type: "string",
+            oneOf: [
+              { const: "small", title: "Small" },
+              { const: "large", title: "Large" },
+            ],
+          },
+          schema.to_h,
+        )
+      end
+
+      test "untitled_multi_select returns array + items.enum schema" do
+        schema = EnumSchema.untitled_multi_select(values: ["a", "b", "c"])
+
+        assert_equal(
+          { type: "array", items: { type: "string", enum: ["a", "b", "c"] } },
+          schema.to_h,
+        )
+      end
+
+      test "untitled_multi_select preserves default array" do
+        schema = EnumSchema.untitled_multi_select(values: ["a", "b"], default: ["a"])
+
+        assert_equal ["a"], schema.to_h[:default]
+      end
+
+      test "titled_multi_select returns array + items.anyOf schema" do
+        schema = EnumSchema.titled_multi_select(
+          options: [
+            { value: "us", title: "United States" },
+            { value: "jp", title: "Japan" },
+          ],
+        )
+
+        assert_equal(
+          {
+            type: "array",
+            items: {
+              anyOf: [
+                { const: "us", title: "United States" },
+                { const: "jp", title: "Japan" },
+              ],
+            },
+          },
+          schema.to_h,
+        )
+      end
+
+      test "legacy_titled returns enum + enumNames" do
+        schema = EnumSchema.legacy_titled(
+          values: ["s", "m", "l"],
+          value_titles: ["Small", "Medium", "Large"],
+        )
+
+        assert_equal(
+          {
+            type: "string",
+            enum: ["s", "m", "l"],
+            enumNames: ["Small", "Medium", "Large"],
+          },
+          schema.to_h,
+        )
+      end
+
+      test "title and description are included when provided" do
+        schema = EnumSchema.untitled_single_select(
+          values: ["a"],
+          title: "Color",
+          description: "Pick a color",
+        )
+
+        assert_equal "Color", schema.to_h[:title]
+        assert_equal "Pick a color", schema.to_h[:description]
+      end
+
+      test "raises ArgumentError when values array is empty" do
+        assert_raises(ArgumentError) do
+          EnumSchema.untitled_single_select(values: [])
+        end
+      end
+
+      test "raises ArgumentError when titled options miss :value" do
+        assert_raises(ArgumentError) do
+          EnumSchema.titled_single_select(options: [{ title: "missing value" }])
+        end
+      end
+
+      test "raises ArgumentError when titled options miss :title" do
+        assert_raises(ArgumentError) do
+          EnumSchema.titled_single_select(options: [{ value: "v" }])
+        end
+      end
+
+      test "raises ArgumentError when legacy value_titles length differs" do
+        assert_raises(ArgumentError) do
+          EnumSchema.legacy_titled(values: ["a", "b"], value_titles: ["A"])
+        end
+      end
+
+      test "preserves an empty-string default value" do
+        # Regression for `unless @default.nil?`: empty-but-non-nil defaults must still survive `to_h`
+        # (the guard distinguishes nil from "absent vs supplied", not truthy vs falsey).
+        schema = EnumSchema.untitled_single_select(values: ["", "yes", "no"], default: "")
+
+        assert_equal "", schema.to_h[:default]
+      end
+
+      test "preserves an empty-array default for multi-select" do
+        schema = EnumSchema.untitled_multi_select(values: ["a", "b"], default: [])
+
+        assert_equal [], schema.to_h[:default]
+      end
+    end
+  end
+end