feat(LTI): Add LTI API show endpoint for external tools

flag = none
refs: CAL-23

Test Plan:
  - Specs pass

Change-Id: Ia90f71640693fb6202ba62540d15be00717896bb
Reviewed-on: https://gerrit.instructure.com/c/canvas-lms/+/236650
Tested-by: Service Cloud Jenkins <svc.cloudjenkins@instructure.com>
QA-Review: Alex Slaughter <aslaughter@instructure.com>
Product-Review: Alex Slaughter <aslaughter@instructure.com>
Reviewed-by: Aaron Ogata <aogata@instructure.com>

app/controllers/lti/account_external_tools_controller.rb

@@ -47,12 +47,13 @@ module Lti
     end
 
     def show
-      # Will add in seperate PS
+      tool = tools.active.find(params['external_tool_id'])
+      render json: external_tool_json(tool, context, @current_user, session), content_type: MIME_TYPE
     end
 
     def index
-      @tools = Api.paginate(ContextExternalTool.all_tools_for(context), self, account_external_tools_index_path(params[:account_id]))
-      render json: external_tools_json(@tools, context, @current_user, session), content_type: MIME_TYPE
+      api = Api.paginate(tools, self, account_external_tools_index_path(params[:account_id]))
+      render json: external_tools_json(api, context, @current_user, session), content_type: MIME_TYPE
     end
 
     def destroy
@@ -65,6 +66,10 @@ module Lti
       ACTION_SCOPE_MATCHERS.fetch(action_name, self.class.none)
     end
 
+    def tools
+      @tools ||= ContextExternalTool.all_tools_for(context)
+    end
+
     def context
       @context ||= Account.active.find_by(lti_context_id: params[:account_id])
     end

lib/token_scopes.rb

@@ -59,7 +59,7 @@ class TokenScopes
   }.freeze
   LTI_AGS_SCOPES = [ LTI_AGS_LINE_ITEM_SCOPE, LTI_AGS_LINE_ITEM_READ_ONLY_SCOPE, LTI_AGS_RESULT_READ_ONLY_SCOPE, LTI_AGS_SCORE_SCOPE ].freeze
   LTI_HIDDEN_SCOPES = {
-    LTI_CREATE_ACCOUNT_EXTERNAL_TOOLS_SCOPE => I18n.t("Can create extneral tools."),
+    LTI_CREATE_ACCOUNT_EXTERNAL_TOOLS_SCOPE => I18n.t("Can create external tools."),
     LTI_DESTROY_ACCOUNT_EXTERNAL_TOOLS_SCOPE => I18n.t("Can destroy external tools."),
     LTI_LIST_ACCOUNT_EXTERNAL_TOOLS_SCOPE => I18n.t("Can list external tools."),
     LTI_SHOW_ACCOUNT_EXTERNAL_TOOLS_SCOPE => I18n.t("Can show external tools."),

spec/controllers/lti/account_external_tools_controller_spec.rb

@@ -31,6 +31,17 @@ describe Lti::AccountExternalToolsController do
     root_account.save
   end
 
+  describe '#show' do
+    it_behaves_like 'lti services' do
+      let(:action) { :show }
+      let(:expected_mime_type) { described_class::MIME_TYPE }
+      let(:scope_to_remove) { "https://canvas.instructure.com/lti/account_external_tools/scope/show"}
+      let(:params_overrides) do
+        { account_id: root_account.lti_context_id, external_tool_id: tool.id }
+      end
+    end
+  end
+
   describe '#index' do
     it_behaves_like 'lti services' do
       let(:action) { :index }