Allow tempfile_for_url to take a URL with no path

Ran into this locally when testing some new code where I use this

refs INTEROP-9084
flag=none

Test plan:
- specs

Change-Id: Idea84e7b4b1465bb942f833eb26299a3585f4aa3
Reviewed-on: https://gerrit.instructure.com/c/canvas-lms/+/370053


Reviewed-by: David Varga <d.varga@instructure.com>
QA-Review: David Varga <d.varga@instructure.com>
Tested-by: Service Cloud Jenkins <svc.cloudjenkins@instructure.com>
Product-Review: Evan Battaglia <ebattaglia@instructure.com>

gems/canvas_http/lib/canvas_http.rb

@@ -323,9 +323,10 @@ module CanvasHttp
   # returns a tempfile with a filename based on the uri (same extension, if
   # there was an extension)
   def self.tempfile_for_uri(uri)
-    basename = File.basename(uri.path)
+    basename = File.basename(uri.path || "")
     basename, ext = basename.split(".", 2)
-    basename = basename.slice(0, 100)
+    basename = (basename || "").slice(0, 100)
+
     tmpfile = if ext
                 Tempfile.new([basename, ext])
               else

gems/canvas_http/spec/canvas_http_spec.rb

@@ -298,8 +298,9 @@ describe "CanvasHttp" do
   end
 
   describe ".tempfile_for_url" do
+    let(:tempfile) { double("tempfile") }
+
     before do
-      tempfile = double("tempfile")
       allow(tempfile).to receive(:binmode)
       allow(Tempfile).to receive(:new).and_return(tempfile)
     end
@@ -308,6 +309,11 @@ describe "CanvasHttp" do
       expect(Tempfile).to receive(:new).with("1234567890" * 10)
       CanvasHttp.tempfile_for_uri(URI.parse("1234567890" * 12))
     end
+
+    it "doesn't crash when given a URI with no path" do
+      res = CanvasHttp.tempfile_for_uri(URI.parse("http://example.com"))
+      expect(res).to eq(tempfile)
+    end
   end
 
   describe ".connection_for_uri" do