Add test that reads ion-tests

.gitmodules

@@ -1,3 +1,6 @@
 [submodule "partiql-conformance-tests/partiql-tests"]
 	path = partiql-conformance-tests/partiql-tests
 	url = https://github.com/partiql/partiql-tests.git
+[submodule "extension/partiql-extension-ion/resources/ion-tests"]
+	path = extension/partiql-extension-ion/resources/ion-tests
+	url = https://github.com/amazon-ion/ion-tests/

extension/partiql-extension-ion/Cargo.toml

@@ -45,6 +45,7 @@ peekmore = "1.3"
 
 [dev-dependencies]
 insta = "1"
+walkdir = "2.5"
 
 [features]
 default = []

extension/partiql-extension-ion/src/boxed_ion.rs

@@ -538,11 +538,14 @@ impl BoxedIon {
             }
             BoxedIonStreamType::Stream => BoxedIonValue::Stream(),
             BoxedIonStreamType::SingleTLV => {
-                let elt = reader.next().expect("ion value")?;
-                if reader.peek().is_some() {
-                    // TODO error on stream instead of TLV?
+                if let Some(elt) = reader.next() {
+                    if reader.peek().is_some() {
+                        // TODO error on stream instead of TLV?
+                    }
+                    BoxedIonValue::Value(elt?)
+                } else {
+                    BoxedIonValue::Sequence(Vec::new().into())
                 }
-                BoxedIonValue::Value(elt)
             }
         })
     }