don't 404 for submission that was not created yet

Change-Id: I67dffd8f8fce13e3ac21f988e67f7e84d9eba4d0
Reviewed-on: https://gerrit.instructure.com/6090
Tested-by: Hudson <hudson@instructure.com>
Reviewed-by: Brian Palmer <brianp@instructure.com>

Author: ryankshaw

app/controllers/submissions_api_controller.rb

@@ -132,7 +132,7 @@ def for_students
   def show
     @assignment = @context.assignments.active.find(params[:assignment_id])
     @user = get_user_considering_section(params[:id])
-    @submission = @assignment.submissions.find_by_user_id(@user.id) or raise ActiveRecord::RecordNotFound
+    @submission = @assignment.submissions.find_or_initialize_by_user_id(@user.id) or raise ActiveRecord::RecordNotFound
     if authorized_action(@submission, @current_user, :read)
       includes = Array(params[:include])
       render :json => submission_json(@submission, @assignment, includes).to_json

spec/apis/v1/submissions_api_spec.rb

@@ -36,18 +36,32 @@ def submit_homework(assignment, student, opts = {:body => "test!"})
     sub
   end
 
-  it "should 404 if there is no submission" do
+  it "should not 404 if there is no submission" do
     student = user(:active_all => true)
     course_with_teacher(:active_all => true)
     @course.enroll_student(student).accept!
     @assignment = @course.assignments.create!(:title => 'assignment1', :grading_type => 'points', :points_possible => 12)
-    raw_api_call(:get,
+    json = api_call(:get,
           "/api/v1/courses/#{@course.id}/assignments/#{@assignment.id}/submissions/#{student.id}.json",
           { :controller => 'submissions_api', :action => 'show',
             :format => 'json', :course_id => @course.id.to_s,
             :assignment_id => @assignment.id.to_s, :id => student.id.to_s },
           { :include => %w(submission_history submission_comments rubric_assessment) })
-    response.status.should match /404/
+    json.should == {
+      "assignment_id" => @assignment.id,
+      "preview_url" => "http://www.example.com/courses/#{@course.id}/assignments/#{@assignment.id}/submissions/#{student.id}?preview=1",
+      "user_id"=>student.id,
+      "grade"=>nil,
+      "body"=>nil,
+      "submitted_at"=>nil,
+      "submission_history"=>[],
+      "attempt"=>nil,
+      "url"=>nil,
+      "submission_type"=>nil,
+      "submission_comments"=>[],
+      "grade_matches_current_submission"=>nil,
+      "score"=>nil
+    }
   end
 
   describe "using section ids" do