[wasm] Add ESM integration tests for wasm:js/string-constants builtin

wasm/jsapi/esm-integration/resources/js-string-constants.wat

@@ -0,0 +1,11 @@
+(module
+  (import "wasm:js/string-constants" "" (global $empty externref))
+  (import "wasm:js/string-constants" "\00" (global $null_byte externref))
+  (import "wasm:js/string-constants" "hello" (global $hello externref))
+  (import "wasm:js/string-constants" "\f0\9f\98\80" (global $emoji externref))
+
+  (export "empty" (global $empty))
+  (export "nullByte" (global $null_byte))
+  (export "hello" (global $hello))
+  (export "emoji" (global $emoji))
+)

wasm/jsapi/esm-integration/source-phase-string-builtins.tentative.any.js

@@ -37,3 +37,4 @@ promise_test(async () => {
 
   assert_equals(imports.length, 0);
 }, "Source phase import should handle string builtin import reflection correctly");
+

wasm/jsapi/esm-integration/source-phase-string-constants.tentative.any.js

@@ -0,0 +1,32 @@
+// META: global=window,dedicatedworker,jsshell,shadowrealm
+
+promise_test(async () => {
+  const wasmModuleSource = await import.source("./resources/js-string-constants.wasm");
+
+  const instance = new WebAssembly.Instance(wasmModuleSource, {});
+
+  assert_equals(instance.exports.empty.value, "");
+  assert_equals(instance.exports.nullByte.value, "\0");
+  assert_equals(instance.exports.hello.value, "hello");
+  assert_equals(instance.exports.emoji.value, "\u{1F600}");
+}, "String constants from wasm:js/string-constants should be supported in source phase imports");
+
+promise_test(async () => {
+  const wasmModuleSource = await import.source("./resources/js-string-constants.wasm");
+
+  const exports = WebAssembly.Module.exports(wasmModuleSource);
+  const exportNames = exports.map((exp) => exp.name);
+
+  assert_true(exportNames.includes("empty"));
+  assert_true(exportNames.includes("nullByte"));
+  assert_true(exportNames.includes("hello"));
+  assert_true(exportNames.includes("emoji"));
+}, "Source phase import should properly expose string constants exports");
+
+promise_test(async () => {
+  const wasmModuleSource = await import.source("./resources/js-string-constants.wasm");
+
+  const imports = WebAssembly.Module.imports(wasmModuleSource);
+
+  assert_equals(imports.length, 0);
+}, "Source phase import should handle string constants import reflection correctly");

wasm/jsapi/esm-integration/string-builtins.tentative.any.js

@@ -10,3 +10,4 @@ promise_test(async () => {
   assert_equals(wasmModule.testString("hello"), 1);
   assert_equals(wasmModule.testString(42), 0);
 }, "String builtins should be supported in imports in ESM integration");
+

wasm/jsapi/esm-integration/string-constants.tentative.any.js

@@ -0,0 +1,10 @@
+// META: global=window,dedicatedworker,jsshell,shadowrealm
+
+promise_test(async () => {
+  const wasmModule = await import("./resources/js-string-constants.wasm");
+
+  assert_equals(wasmModule.empty, "");
+  assert_equals(wasmModule.nullByte, "\0");
+  assert_equals(wasmModule.hello, "hello");
+  assert_equals(wasmModule.emoji, "\u{1F600}");
+}, "String constants from wasm:js/string-constants should be supported in ESM integration");