feat: Add support for import assertions and JSON modules (#12866)

This commit adds proper support for import assertions and JSON modules.

Implementation of "core/modules.rs" was changed to account for multiple possible
module types, instead of always assuming that the code is an "ES module". In
effect "ModuleMap" now has knowledge about each modules' type (stored via
"ModuleType" enum). Module loading pipeline now stores information about
expected module type for each request and validates that expected type matches
discovered module type based on file's "MediaType".

Relevant tests were added to "core/modules.rs" and integration tests,
additionally multiple WPT tests were enabled.

There are still some rough edges in the implementation and not all WPT were
enabled, due to:
a) unclear BOM handling in source code by "FileFetcher"
b) design limitation of Deno's "FileFetcher" that doesn't download the same
module multiple times in a single run

Co-authored-by: Kitson Kelly <me@kitsonkelly.com>

21 files changed, 131 insertions, 12 deletions

diff --git a/cli/config_file.rs b/cli/config_file.rs
index 363a215eb..5cd76eaca 100644
--- a/cli/config_file.rs
+++ b/cli/config_file.rs
@@ -104,6 +104,7 @@ pub const IGNORED_COMPILER_OPTIONS: &[&str] = &[
   "paths",
   "preserveConstEnums",
   "reactNamespace",
+  "resolveJsonModule",
   "rootDir",
   "rootDirs",
   "skipLibCheck",
diff --git a/cli/emit.rs b/cli/emit.rs
index c9a90abb7..3aa2c4794 100644
--- a/cli/emit.rs
+++ b/cli/emit.rs
@@ -153,6 +153,7 @@ pub(crate) fn get_ts_config(
         "isolatedModules": true,
         "lib": lib,
         "module": "esnext",
+        "resolveJsonModule": true,
         "strict": true,
         "target": "esnext",
         "tsBuildInfoFile": "deno:///.tsbuildinfo",
@@ -186,6 +187,7 @@ pub(crate) fn get_ts_config(
       "jsx": "react",
       "jsxFactory": "React.createElement",
       "jsxFragmentFactory": "React.Fragment",
+      "resolveJsonModule": true,
     })),
     ConfigType::RuntimeEmit { tsc_emit } => {
       let mut ts_config = TsConfig::new(json!({
@@ -403,14 +405,15 @@ pub(crate) fn check_and_maybe_emit(
           log::debug!("module missing, skipping emit for {}", specifier);
           continue;
         };
-        // Sometimes if `tsc` sees a CommonJS file it will _helpfully_ output it
-        // to ESM, which we don't really want to do unless someone has enabled
-        // check_js.
-        if !check_js
-          && matches!(
-            media_type,
-            MediaType::JavaScript | MediaType::Cjs | MediaType::Mjs
-          )
+        // Sometimes if `tsc` sees a CommonJS file or a JSON module, it will
+        // _helpfully_ output it, which we don't really want to do unless
+        // someone has enabled check_js.
+        if matches!(media_type, MediaType::Json)
+          || (!check_js
+            && matches!(
+              media_type,
+              MediaType::JavaScript | MediaType::Cjs | MediaType::Mjs
+            ))
         {
           log::debug!("skipping emit for {}", specifier);
           continue;
@@ -429,7 +432,10 @@ pub(crate) fn check_and_maybe_emit(
           MediaType::Dts | MediaType::Dcts | MediaType::Dmts => {
             cache.set(CacheType::Declaration, &specifier, emit.data)?;
           }
-          _ => unreachable!(),
+          _ => unreachable!(
+            "unexpected media_type {} {}",
+            emit.media_type, specifier
+          ),
         }
       }
     }
diff --git a/cli/lsp/language_server.rs b/cli/lsp/language_server.rs
index aa465cf48..e9e446918 100644
--- a/cli/lsp/language_server.rs
+++ b/cli/lsp/language_server.rs
@@ -569,6 +569,7 @@ impl Inner {
       "lib": ["deno.ns", "deno.window"],
       "module": "esnext",
       "noEmit": true,
+      "resolveJsonModule": true,
       "strict": true,
       "target": "esnext",
       "useDefineForClassFields": true,
diff --git a/cli/proc_state.rs b/cli/proc_state.rs
index 1a0f61e71..d82f8d017 100644
--- a/cli/proc_state.rs
+++ b/cli/proc_state.rs
@@ -31,6 +31,7 @@ use deno_core::url::Url;
 use deno_core::CompiledWasmModuleStore;
 use deno_core::ModuleSource;
 use deno_core::ModuleSpecifier;
+use deno_core::ModuleType;
 use deno_core::SharedArrayBufferStore;
 use deno_graph::create_graph;
 use deno_graph::Dependency;
@@ -68,6 +69,7 @@ pub struct ProcState(Arc<Inner>);
 enum ModuleEntry {
   Module {
     code: String,
+    media_type: MediaType,
     dependencies: BTreeMap<String, Dependency>,
   },
   Error(ModuleGraphError),
@@ -584,6 +586,7 @@ impl ProcState {
                 | MediaType::Unknown
                 | MediaType::Cjs
                 | MediaType::Mjs
+                | MediaType::Json
             ) {
               module.maybe_source().unwrap_or("").to_string()
             // The emit may also be missing when a declaration file is in the
@@ -602,7 +605,11 @@ impl ProcState {
               module.maybe_dependencies().cloned().unwrap_or_default();
             graph_data.modules.insert(
               specifier.clone(),
-              ModuleEntry::Module { code, dependencies },
+              ModuleEntry::Module {
+                code,
+                dependencies,
+                media_type: *media_type,
+              },
             );
             if let Some(dependencies) = module.maybe_dependencies() {
               for dep in dependencies.values() {
@@ -724,10 +731,16 @@ impl ProcState {
       _ => &specifier,
     };
     match graph_data.modules.get(found_specifier) {
-      Some(ModuleEntry::Module { code, .. }) => Ok(ModuleSource {
+      Some(ModuleEntry::Module {
+        code, media_type, ..
+      }) => Ok(ModuleSource {
         code: code.clone(),
         module_url_specified: specifier.to_string(),
         module_url_found: found_specifier.to_string(),
+        module_type: match media_type {
+          MediaType::Json => ModuleType::Json,
+          _ => ModuleType::JavaScript,
+        },
       }),
       _ => Err(anyhow!(
         "Loading unprepared module: {}",
diff --git a/cli/standalone.rs b/cli/standalone.rs
index 47b0e2aa8..d7fbb3106 100644
--- a/cli/standalone.rs
+++ b/cli/standalone.rs
@@ -164,6 +164,7 @@ impl ModuleLoader for EmbeddedModuleLoader {
 
       Ok(deno_core::ModuleSource {
         code,
+        module_type: deno_core::ModuleType::JavaScript,
         module_url_specified: module_specifier.to_string(),
         module_url_found: module_specifier.to_string(),
       })
diff --git a/cli/tests/integration/run_tests.rs b/cli/tests/integration/run_tests.rs
index b6929b58a..c04e4731c 100644
--- a/cli/tests/integration/run_tests.rs
+++ b/cli/tests/integration/run_tests.rs
@@ -2407,3 +2407,36 @@ fn issue12807() {
     .unwrap();
   assert!(status.success());
 }
+
+itest!(import_assertions_static_import {
+  args: "run --allow-read import_assertions/static_import.ts",
+  output: "import_assertions/static_import.out",
+});
+
+itest!(import_assertions_static_export {
+  args: "run --allow-read import_assertions/static_export.ts",
+  output: "import_assertions/static_export.out",
+});
+
+itest!(import_assertions_static_error {
+  args: "run --allow-read import_assertions/static_error.ts",
+  output: "import_assertions/static_error.out",
+  exit_code: 1,
+});
+
+itest!(import_assertions_dynamic_import {
+  args: "run --allow-read import_assertions/dynamic_import.ts",
+  output: "import_assertions/dynamic_import.out",
+});
+
+itest!(import_assertions_dynamic_error {
+  args: "run --allow-read import_assertions/dynamic_error.ts",
+  output: "import_assertions/dynamic_error.out",
+  exit_code: 1,
+});
+
+itest!(import_assertions_type_check {
+  args: "run --allow-read import_assertions/type_check.ts",
+  output: "import_assertions/type_check.out",
+  exit_code: 1,
+});
diff --git a/cli/tests/testdata/import_assertions/data.json b/cli/tests/testdata/import_assertions/data.json
new file mode 100644
index 000000000..37b3ee1e0
--- /dev/null
+++ b/cli/tests/testdata/import_assertions/data.json
@@ -0,0 +1,6 @@
+{
+  "a": "b",
+  "c": {
+    "d": 10
+  }
+}
diff --git a/cli/tests/testdata/import_assertions/dynamic_error.out b/cli/tests/testdata/import_assertions/dynamic_error.out
new file mode 100644
index 000000000..1ad40889b
--- /dev/null
+++ b/cli/tests/testdata/import_assertions/dynamic_error.out
@@ -0,0 +1,5 @@
+[WILDCARD]
+error: Uncaught (in promise) TypeError: Expected a "JavaScript" module but loaded a "JSON" module.
+const data = await import("./data.json");
+             ^
+    at async [WILDCARD]dynamic_error.ts:1:14
diff --git a/cli/tests/testdata/import_assertions/dynamic_error.ts b/cli/tests/testdata/import_assertions/dynamic_error.ts
new file mode 100644
index 000000000..2d9c6757f
--- /dev/null
+++ b/cli/tests/testdata/import_assertions/dynamic_error.ts
@@ -0,0 +1,3 @@
+const data = await import("./data.json");
+
+console.log(data);
diff --git a/cli/tests/testdata/import_assertions/dynamic_import.out b/cli/tests/testdata/import_assertions/dynamic_import.out
new file mode 100644
index 000000000..3280e0f53
--- /dev/null
+++ b/cli/tests/testdata/import_assertions/dynamic_import.out
@@ -0,0 +1,2 @@
+[WILDCARD]
+Module { default: { a: "b", c: { d: 10 } } }
diff --git a/cli/tests/testdata/import_assertions/dynamic_import.ts b/cli/tests/testdata/import_assertions/dynamic_import.ts
new file mode 100644
index 000000000..d6983852c
--- /dev/null
+++ b/cli/tests/testdata/import_assertions/dynamic_import.ts
@@ -0,0 +1,3 @@
+const data = await import("./data.json", { assert: { type: "json" } });
+
+console.log(data);
diff --git a/cli/tests/testdata/import_assertions/static_error.out b/cli/tests/testdata/import_assertions/static_error.out
new file mode 100644
index 000000000..8524079de
--- /dev/null
+++ b/cli/tests/testdata/import_assertions/static_error.out
@@ -0,0 +1,5 @@
+[WILDCARD]
+error: An unsupported media type was attempted to be imported as a module.
+  Specifier: [WILDCARD]data.json
+  MediaType: Json
+    at [WILDCARD]static_error.ts:1:18
diff --git a/cli/tests/testdata/import_assertions/static_error.ts b/cli/tests/testdata/import_assertions/static_error.ts
new file mode 100644
index 000000000..0bc3a93f8
--- /dev/null
+++ b/cli/tests/testdata/import_assertions/static_error.ts
@@ -0,0 +1,3 @@
+import data from "./data.json";
+
+console.log(data);
diff --git a/cli/tests/testdata/import_assertions/static_export.out b/cli/tests/testdata/import_assertions/static_export.out
new file mode 100644
index 000000000..42fbc066c
--- /dev/null
+++ b/cli/tests/testdata/import_assertions/static_export.out
@@ -0,0 +1,2 @@
+[WILDCARD]
+{ a: "b", c: { d: 10 } }
diff --git a/cli/tests/testdata/import_assertions/static_export.ts b/cli/tests/testdata/import_assertions/static_export.ts
new file mode 100644
index 000000000..ac3ee694f
--- /dev/null
+++ b/cli/tests/testdata/import_assertions/static_export.ts
@@ -0,0 +1,3 @@
+import data from "./static_reexport.ts";
+
+console.log(data);
diff --git a/cli/tests/testdata/import_assertions/static_import.out b/cli/tests/testdata/import_assertions/static_import.out
new file mode 100644
index 000000000..42fbc066c
--- /dev/null
+++ b/cli/tests/testdata/import_assertions/static_import.out
@@ -0,0 +1,2 @@
+[WILDCARD]
+{ a: "b", c: { d: 10 } }
diff --git a/cli/tests/testdata/import_assertions/static_import.ts b/cli/tests/testdata/import_assertions/static_import.ts
new file mode 100644
index 000000000..180ab75f2
--- /dev/null
+++ b/cli/tests/testdata/import_assertions/static_import.ts
@@ -0,0 +1,3 @@
+import data from "./data.json" assert { type: "json" };
+
+console.log(data);
diff --git a/cli/tests/testdata/import_assertions/static_reexport.ts b/cli/tests/testdata/import_assertions/static_reexport.ts
new file mode 100644
index 000000000..81af428be
--- /dev/null
+++ b/cli/tests/testdata/import_assertions/static_reexport.ts
@@ -0,0 +1 @@
+export { default } from "./data.json" assert { type: "json" };
diff --git a/cli/tests/testdata/import_assertions/type_check.out b/cli/tests/testdata/import_assertions/type_check.out
new file mode 100644
index 000000000..8e1387456
--- /dev/null
+++ b/cli/tests/testdata/import_assertions/type_check.out
@@ -0,0 +1,5 @@
+[WILDCARD]
+error: TS2339 [ERROR]: Property 'foo' does not exist on type '{ a: string; c: { d: number; }; }'.
+console.log(data.foo);
+                 ~~~
+    at [WILDCARD]type_check.ts:3:18
diff --git a/cli/tests/testdata/import_assertions/type_check.ts b/cli/tests/testdata/import_assertions/type_check.ts
new file mode 100644
index 000000000..19adb3eae
--- /dev/null
+++ b/cli/tests/testdata/import_assertions/type_check.ts
@@ -0,0 +1,3 @@
+import data from "./data.json" assert { type: "json" };
+
+console.log(data.foo);
diff --git a/cli/tsc.rs b/cli/tsc.rs
index bc18efee0..f76fb18fb 100644
--- a/cli/tsc.rs
+++ b/cli/tsc.rs
@@ -352,6 +352,24 @@ struct LoadArgs {
   specifier: String,
 }
 
+fn as_ts_script_kind(media_type: &MediaType) -> i32 {
+  match media_type {
+    MediaType::JavaScript => 1,
+    MediaType::Jsx => 2,
+    MediaType::Mjs => 1,
+    MediaType::Cjs => 1,
+    MediaType::TypeScript => 3,
+    MediaType::Mts => 3,
+    MediaType::Cts => 3,
+    MediaType::Dts => 3,
+    MediaType::Dmts => 3,
+    MediaType::Dcts => 3,
+    MediaType::Tsx => 4,
+    MediaType::Json => 6,
+    _ => 0,
+  }
+}
+
 fn op_load(state: &mut State, args: Value) -> Result<Value, AnyError> {
   let v: LoadArgs = serde_json::from_value(args)
     .context("Invalid request from JavaScript for \"op_load\".")?;
@@ -395,7 +413,7 @@ fn op_load(state: &mut State, args: Value) -> Result<Value, AnyError> {
   };
 
   Ok(
-    json!({ "data": data, "hash": hash, "scriptKind": media_type.as_ts_script_kind() }),
+    json!({ "data": data, "hash": hash, "scriptKind": as_ts_script_kind(&media_type) }),
   )
 }