Group the RequestStore examples by what they exercise

Four undifferentiated examples under one describe, where a lead example plus a
context for the edge case says the same thing - matching bike_services/register_spec.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

Author: eld120

spec/services/saml/request_store_spec.rb

@@ -3,40 +3,30 @@
 RSpec.describe Saml::RequestStore do
   let(:request_id) { "_abc-123" }
   let(:org_slug) { "some-university" }
+  let(:token) { described_class.create(request_id:, org_slug:) }
 
-  describe "create and claim" do
-    it "round trips the transaction" do
-      token = described_class.create(request_id:, org_slug:)
+  describe "create" do
+    it "issues a distinct expiring token that round trips the transaction" do
       expect(token).to be_present
+      expect(RedisPool.conn { |r| r.ttl("saml_request:#{token}") })
+        .to be_within(5).of(described_class::TTL.to_i)
       expect(described_class.claim(token)).to eq({org_slug:, request_id:})
-    end
-
-    it "only claims once" do
-      token = described_class.create(request_id:, org_slug:)
-      described_class.claim(token)
-      expect(described_class.claim(token)).to be_nil
-    end
-
-    it "issues a distinct token per request" do
-      tokens = Array.new(3) { described_class.create(request_id:, org_slug:) }
-      expect(tokens.uniq.count).to eq 3
-    end
-
-    it "expires" do
-      token = described_class.create(request_id:, org_slug:)
-      ttl = RedisPool.conn { |r| r.ttl("saml_request:#{token}") }
-      expect(ttl).to be_within(5).of(described_class::TTL.to_i)
+      expect(described_class.create(request_id:, org_slug:)).to_not eq token
     end
   end
 
   describe "claim" do
-    it "is nil for a blank token" do
-      expect(described_class.claim(nil)).to be_nil
-      expect(described_class.claim("")).to be_nil
+    it "succeeds once, the token being single use" do
+      expect(described_class.claim(token)).to eq({org_slug:, request_id:})
+      expect(described_class.claim(token)).to be_nil
     end
 
-    it "is nil for an unknown token" do
-      expect(described_class.claim("not-a-real-token")).to be_nil
+    context "a token we never issued" do
+      it "is nil rather than raising" do
+        expect(described_class.claim(nil)).to be_nil
+        expect(described_class.claim("")).to be_nil
+        expect(described_class.claim("not-a-real-token")).to be_nil
+      end
     end
   end
 end