diff --git a/crates/interpreter/test.sh b/crates/interpreter/test.sh
index 5c75252b..de800795 100755
--- a/crates/interpreter/test.sh
+++ b/crates/interpreter/test.sh
@@ -19,7 +19,14 @@ set -e
 
 ensure_submodule third_party/WebAssembly/spec
 
-# TODO(cleanup): Make sure we cover all spec/test/core tests using _test_diff.
+list_files() {
+  find ../../third_party/WebAssembly/spec/test/core \
+    -maxdepth 1 -name '*.wast' -execdir basename -s .wast {} \;
+}
+list_tests() {
+  sed -n 's/^test!(.*, "\([^"]*\)".*);$/\1/p;s/^test!(\([^,]*\).*);$/\1/p' tests/spec.rs
+}
+diff_sorted tests/spec.rs "$(list_files | sort)" $(list_tests)
 
 test_helper
 
diff --git a/scripts/test-helper.sh b/scripts/test-helper.sh
index 3c84eaae..89965e86 100644
--- a/scripts/test-helper.sh
+++ b/scripts/test-helper.sh
@@ -51,6 +51,14 @@ check_software_crypto() {
   fi
 }
 
+# diff_sorted <name> <left> <right>..
+# <name> is the name of the <right> list
+# <left> is a sorted list after word expansion
+# <right>.. is a sorted list
+diff_sorted() {
+  _test_diff "$@"
+}
+
 test_helper() {
   _test_desc | grep -Ev 'cargo (check|(miri )?test) --(lib|(bin|test|example)=[^ ]*)( |$)' \
     && e 'Invalid description (invalid commands are listed above).'