Add RSpec suite with WebMock: core, OAuth, pagination, and resource behavior

spec/fiken/error_spec.rb

@@ -0,0 +1,33 @@
+# frozen_string_literal: true
+
+RSpec.describe Fiken::Error do
+  describe ".from_response" do
+    it "maps known statuses to specific subclasses" do
+      {
+        400 => Fiken::BadRequest,
+        401 => Fiken::Unauthorized,
+        403 => Fiken::Forbidden,
+        404 => Fiken::NotFound,
+        422 => Fiken::UnprocessableEntity,
+        429 => Fiken::RateLimited
+      }.each do |status, klass|
+        expect(described_class.from_response(status, {})).to be_a(klass)
+      end
+    end
+
+    it "maps unknown 5xx statuses to ServerError" do
+      expect(described_class.from_response(503, "")).to be_a(Fiken::ServerError)
+    end
+
+    it "extracts a message from a JSON error body" do
+      error = described_class.from_response(400, { "message" => "Bad slug" })
+      expect(error.message).to eq("Bad slug")
+      expect(error.status).to eq(400)
+    end
+
+    it "falls back to a generic message when the body has none" do
+      error = described_class.from_response(404, "")
+      expect(error.message).to eq("Fiken API error (HTTP 404)")
+    end
+  end
+end