Send all available variable substitutions in TCP

Closes PLAT-2606

Test Plan:
- Install an LTI2 tool and verify
  that the tool consumer profile now contains
  all variable expansions in the enabled capability
  section.
- Include these capabilities as parameters, do a
  launch, and verify that the applicable expansions
  are replaced.

Change-Id: Ia97f0184c94eeeb33c5851c715770f209a21c3c2
Reviewed-on: https://gerrit.instructure.com/113014
Reviewed-by: Andrew Butterfield <abutterfield@instructure.com>
QA-Review: August Thornton <august@instructure.com>
Tested-by: Jenkins
Product-Review: Weston Dransfield <wdransfield@instructure.com>

app/models/lti/tool_consumer_profile.rb

@@ -48,30 +48,17 @@ module Lti
 
     DEFAULT_CAPABILITIES = %w(
       basic-lti-launch-request
-      User.id
-      Canvas.api.domain
-      LtiLink.custom.url
-      ToolProxyBinding.custom.url
-      ToolProxy.custom.url
       Canvas.placements.accountNavigation
       Canvas.placements.courseNavigation
       Canvas.placements.assignmentSelection
       Canvas.placements.linkSelection
       Canvas.placements.postGrades
-      User.username
-      Person.email.primary
-      vnd.Canvas.Person.email.sis
-      Person.name.given
-      Person.name.family
-      Person.name.full
-      CourseSection.sourcedId
-      Person.sourcedId
-      Membership.role
-      ToolConsumerProfile.url
       Security.splitSecret
-      Context.id
-      Canvas.assignment.id
-    ).concat(CapabilitiesHelper::SUPPORTED_CAPABILITIES).freeze
+    ).concat(
+      CapabilitiesHelper::SUPPORTED_CAPABILITIES
+    ).concat(
+      Lti::VariableExpander.expansion_keys
+    ).uniq.freeze
 
     RESTRICTED_CAPABILITIES = [
       'Canvas.placements.similarityDetection',

lib/lti/variable_expander.rb

@@ -40,6 +40,10 @@ module Lti
       @expansions || {}
     end
 
+    def self.expansion_keys
+      self.expansions.keys.map { |c| c.to_s[1..-1] }
+    end
+
     CONTROLLER_GUARD = -> { !!@controller }
     COURSE_GUARD = -> { @context.is_a? Course }
     TERM_START_DATE_GUARD = -> { @context.is_a?(Course) && @context.enrollment_term &&

spec/lib/lti/variable_expander_spec.rb

@@ -121,6 +121,16 @@ module Lti
       expect(expanded[:some_name]).to eq "my variable is buried in here ${tests_expan} can you find it?"
     end
 
+    describe '#self.expansion_keys' do
+      let(:expected_keys) do
+        VariableExpander.expansions.keys.map { |c| c.to_s[1..-1] }
+      end
+
+      it 'includes all expansion keys' do
+        expect(VariableExpander.expansion_keys).to eq expected_keys
+      end
+    end
+
     describe '#enabled_capability_params' do
       let(:enabled_capability) {
         %w(TestCapability.Foo

spec/models/lti/tool_consumer_profile_creator_spec.rb

@@ -117,6 +117,11 @@ module Lti
       end
 
       describe '#capabilities' do
+        it 'includes all variable expansions from the variable expander' do
+          expected_caps = VariableExpander.expansion_keys
+          expect(tcp_creator.create.capability_offered).to include(*expected_caps)
+        end
+
         it 'add the basic_launch capability' do
           expect(tcp_creator.create.capability_offered).to include 'basic-lti-launch-request'
         end