Fix package name / import name dichotomy. Add testing.

src/runpython.c

@@ -77,20 +77,31 @@ EM_JS(int, runpython_init_js, (), {
     var jsimports = Module.hiwire_get_value(idimports);
     Module.hiwire_decref(idimports);
 
-    var internal = function() { return Module._runPythonInternal(pycode); };
+    var internal = function(resolve, reject) {
+      try {
+        resolve(Module._runPythonInternal(pycode));
+      } catch (e) {
+        reject(e);
+      }
+    };
 
     if (jsimports.length) {
-      var packages = window.pyodide._module.packages.dependencies;
-      var packageFilter = function(name)
-      {
-        return Object.prototype.hasOwnProperty(packages, name);
-      };
-      jsimports = jsimports.filter(packageFilter);
-      return Module.loadPackage(jsimports, messageCallback).then(internal);
-    } else {
-      var resolve = function(resolve) { return resolve(); };
-      return new Promise(resolve).then(internal);
+      var packageNames = window.pyodide._module.packages.import_name_to_package_name;
+      var packages = {};
+      for (var i = 0; i < jsimports.length; ++i) {
+        var name = jsimports[i];
+        if (packageNames[name] !== undefined) {
+          packages[packageNames[name]] = undefined;
+        }
+      }
+      if (Object.keys(packages).length) {
+        var runInternal = function() {
+          return new Promise(internal);
+        };
+        return Module.loadPackage(Object.keys(packages), messageCallback).then(runInternal);
+      }
     }
+    return new Promise(internal);
   };
 });
 

test/conftest.py

@@ -105,6 +105,35 @@ class SeleniumWrapper:
         return self.run_js(
             'return pyodide.runPython({!r})'.format(code))
 
+    def run_async(self, code):
+        from selenium.common.exceptions import TimeoutException
+        if isinstance(code, str) and code.startswith('\n'):
+            # we have a multiline string, fix indentation
+            code = textwrap.dedent(code)
+        self.run_js(
+            """
+            window.done = false;
+            pyodide.runPythonAsync({!r})
+              .then(function(output) {{ window.output = output; window.error = false; }},
+                    function(output) {{ window.output = output; window.error = true; }})
+              .finally(() => window.done = true);
+            """.format(code)
+        )
+        try:
+            self.wait.until(PackageLoaded())
+        except TimeoutException as exc:
+            _display_driver_logs(self.browser, self.driver)
+            print(self.logs)
+            raise TimeoutException('runPythonAsync timed out')
+        return self.run_js(
+            """
+            if (window.error) {
+              throw window.output;
+            }
+            return window.output;
+            """
+        )
+
     def run_js(self, code):
         if isinstance(code, str) and code.startswith('\n'):
             # we have a multiline string, fix indentation

test/test_python.py

@@ -442,3 +442,73 @@ def test_recursive_dict(selenium_standalone):
         """
     )
     selenium_standalone.run_js("x = pyodide.pyimport('x')")
+
+
+def test_runpythonasync(selenium_standalone):
+    output = selenium_standalone.run_async(
+        """
+        import numpy as np
+        np.zeros(5)
+        """
+    )
+    assert list(output) == [0, 0, 0, 0, 0]
+
+
+def test_runpythonasync_different_package_name(selenium_standalone):
+    output = selenium_standalone.run_async(
+        """
+        import dateutil
+        dateutil.__version__
+        """
+    )
+    assert isinstance(output, str)
+
+
+def test_runpythonasync_no_imports(selenium_standalone):
+    output = selenium_standalone.run_async(
+        """
+        42
+        """
+    )
+    assert output == 42
+
+
+def test_runpythonasync_missing_import(selenium_standalone):
+    try:
+        selenium_standalone.run_async(
+            """
+            import foo
+            """
+        )
+    except selenium_standalone.JavascriptException as e:
+        assert "ModuleNotFoundError" in str(e)
+    else:
+        assert False
+
+
+def test_runpythonasync_exception(selenium_standalone):
+    try:
+        selenium_standalone.run_async(
+            """
+            42 / 0
+            """
+        )
+    except selenium_standalone.JavascriptException as e:
+        assert "ZeroDivisionError" in str(e)
+    else:
+        assert False
+
+
+def test_runpythonasync_exception_after_import(selenium_standalone):
+    try:
+        selenium_standalone.run_async(
+            """
+            import numpy as np
+            x = np.empty(5)
+            42 / 0
+            """
+        )
+    except selenium_standalone.JavascriptException as e:
+        assert "ZeroDivisionError" in str(e)
+    else:
+        assert False