fix: do not error loading Wasm module from JSR (#562)

Author: dsherret

src/graph.rs

@@ -4277,7 +4277,20 @@ impl<'a, 'graph> Builder<'a, 'graph> {
                     ParseModuleAndSourceInfoOptions {
                       specifier: requested_specifier.clone(),
                       maybe_headers: Default::default(),
-                      content: Arc::new([]) as Arc<[u8]>, // we'll load the content later
+                      // we'll load the content later
+                      content: if MediaType::from_specifier(
+                        &requested_specifier,
+                      ) == MediaType::Wasm
+                      {
+                        // TODO(#561): temporary hack until a larger refactor can be done
+                        Arc::new([
+                          // minimum allowed wasm module
+                          0x00, 0x61, 0x73, 0x6D, 0x01, 0x00, 0x00, 0x00, 0x0A,
+                          0x01, 0x00,
+                        ])
+                      } else {
+                        Arc::new([]) as Arc<[u8]>
+                      },
                       maybe_attribute_type: maybe_attribute_type.as_ref(),
                       maybe_referrer: maybe_range.as_ref(),
                       is_root,

tests/integration_test.rs

@@ -307,6 +307,87 @@ async fn test_jsr_version_not_found_then_found() {
   }
 }
 
+#[tokio::test]
+async fn test_jsr_wasm_module() {
+  struct TestLoader;
+
+  impl deno_graph::source::Loader for TestLoader {
+    fn load(
+      &self,
+      specifier: &ModuleSpecifier,
+      options: LoadOptions,
+    ) -> LoadFuture {
+      assert!(!options.is_dynamic);
+      let specifier = specifier.clone();
+      match specifier.as_str() {
+        "file:///main.ts" => Box::pin(async move {
+          Ok(Some(LoadResponse::Module {
+            specifier: specifier.clone(),
+            maybe_headers: None,
+            content: b"import 'jsr:@scope/a@1".to_vec().into(),
+          }))
+        }),
+        "https://jsr.io/@scope/a/meta.json" => Box::pin(async move {
+          Ok(Some(LoadResponse::Module {
+            specifier: specifier.clone(),
+            maybe_headers: None,
+            content: br#"{ "versions": { "1.0.0": {} } }"#.to_vec().into(),
+          }))
+        }),
+        "https://jsr.io/@scope/a/1.0.0_meta.json" => Box::pin(async move {
+          Ok(Some(LoadResponse::Module {
+            specifier: specifier.clone(),
+            maybe_headers: None,
+            content: br#"{
+                "exports": { ".": "./math.wasm" },
+                "manifest": {
+                  "/math.wasm": {
+                    "size": 123,
+                    "checksum": "sha256-b8059cfb1ea623e79efbf432db31595df213c99c6534c58bec9d5f5e069344df"
+                  }
+                },
+                "moduleGraph2": {
+                  "/math.wasm": {
+                    "dependencies": []
+                  }
+                }
+              }"#
+              .to_vec()
+              .into(),
+          }))
+        }),
+        "https://jsr.io/@scope/a/1.0.0/math.wasm" => Box::pin(async move {
+          if options.cache_setting == CacheSetting::Only {
+            Ok(None)
+          } else {
+            Ok(Some(LoadResponse::Module {
+              specifier: specifier.clone(),
+              maybe_headers: None,
+              content: std::fs::read("./tests/testdata/math.wasm")
+                .unwrap()
+                .into(),
+            }))
+          }
+        }),
+        _ => unreachable!(),
+      }
+    }
+  }
+
+  {
+    let loader = TestLoader;
+    let mut graph = ModuleGraph::new(GraphKind::All);
+    graph
+      .build(
+        vec![Url::parse("file:///main.ts").unwrap()],
+        &loader,
+        Default::default(),
+      )
+      .await;
+    graph.valid().unwrap();
+  }
+}
+
 #[tokio::test]
 async fn test_dynamic_imports_with_template_arg() {
   async fn run_test(