import.meta.resolve implementation (#2230)

src/system-core.js

@@ -41,8 +41,12 @@ systemJSPrototype.import = function (id, parentUrl) {
 
 // Hookable createContext function -> allowing eg custom import meta
 systemJSPrototype.createContext = function (parentId) {
+  var loader = this;
   return {
-    url: parentId
+    url: parentId,
+    resolve: function (id, parentUrl) {
+      return Promise.resolve(loader.resolve(id, parentUrl || parentId));
+    }
   };
 };
 

test/browser/core.js

@@ -57,13 +57,51 @@ suite('SystemJS Standard Tests', function() {
     });
   });
 
+  test('import.meta.resolve package maps', function () {
+    return System.import('fixtures/resolve.js').then(function (m) {
+      return m.resolve('a')
+    })
+    .then(function (resolved) {
+      assert.equal(resolved, rootURL + 'b');
+    });
+  });
+
+  test('import.meta.resolve package maps paths', function () {
+    return System.import('fixtures/resolve.js').then(function (m) {
+      return m.resolve('a/')
+    })
+    .then(function (resolved) {
+      assert.equal(resolved, baseURL + 'fixtures/browser/a/');
+    });
+  });
+
   test('Contextual package maps', function () {
     return System.import('fixtures/scope-test/index.js')
     .then(function (m) {
       assert.equal(m.mapdep, 'mapdep');
     });
   });
 
+  test('import.meta.resolve contextual package maps', function () {
+    return System.import('fixtures/resolve.js').then(function (m) {
+      return m.resolve('maptest', baseURL + 'fixtures/browser/scope-test/index.js')
+    })
+    .then(function (resolved) {
+      assert.equal(resolved, baseURL + 'fixtures/browser/contextual-map-dep.js');
+    });
+  });
+
+  test('import.meta.resolve contextual package maps fail', function () {
+    return System.import('fixtures/resolve.js').then(function (m) {
+      return m.resolve('maptest')
+    })
+    .then(function (resolved) {
+      assert.ok(false);
+    }, function (error) {
+      assert.equal(error.message.indexOf('Unable to resolve'), 0);
+    });
+  });
+
   test('Loading named System.register fails', function () {
     return System.import('fixtures/named-register.js')
     .then(function () {
@@ -219,6 +257,15 @@ suite('SystemJS Standard Tests', function() {
     assert.equal(System.get(resolved).auto, 'import');
   });
 
+  test('import.meta.resolve', function () {
+    return System.import('fixtures/resolve.js').then(function (m) {
+      return m.resolve('./test.js')
+    })
+    .then(function (resolved) {
+      assert.equal(resolved, baseURL + 'fixtures/browser/test.js');
+    });
+  });
+
   test('non-enumerable __esModule property export (issue 2090)', function () {
     return System.import('fixtures/__esModule.js').then(function (m) {
       // Even though __esModule is not enumerable on the exported object, it should be preserved on the systemjs namespace

test/fixtures/browser/resolve.js

@@ -0,0 +1,11 @@
+System.register([], function (_export, _context) {
+  return {
+    setters: [],
+    execute: function () {
+      _export({
+        url: _context.meta.url,
+        resolve: _context.meta.resolve
+      });
+    }
+  };
+});