Lazily throw pubspec parsing exceptions.

sdk/lib/_internal/pub/lib/src/validator/pubspec_field.dart

Index: sdk/lib/_internal/pub/lib/src/validator/pubspec_field.dart
diff --git a/sdk/lib/_internal/pub/lib/src/validator/pubspec_field.dart b/sdk/lib/_internal/pub/lib/src/validator/pubspec_field.dart
index e9d2d35452f87f98e005fc7ee28f5c5db7a14667..7ff8ec77c459ae1c04fba2ff45c1d03d44f62267 100644
--- a/sdk/lib/_internal/pub/lib/src/validator/pubspec_field.dart
+++ b/sdk/lib/_internal/pub/lib/src/validator/pubspec_field.dart
@@ -16,44 +16,91 @@ class PubspecFieldValidator extends Validator {
     : super(entrypoint);
 
   Future validate() {
-    // The types of all fields are validated when the pubspec is parsed.
+    _validateAuthors();
+    _validateFieldIsString('description');
+    _validateFieldIsString('homepage');
+    _validateFieldUrl('homepage');
+    _validateFieldUrl('documentation');
+
+    // Any complex parsing errors in version will be exposed through
+    // [Pubspec.allErrors].
+    _validateFieldIsString('version');
+
+    // Pubspec errors are detected lazily, so we make sure there aren't any
+    // here.
+    for (var error in entrypoint.root.pubspec.allErrors) {
+      errors.add('In your pubspec.yaml, ${error.message}');
+    }
+
+    return new Future.value();
+  }
+
+  /// Adds an error if the "author" or "authors" field doesn't exist or has the
+  /// wrong type.
+  void _validateAuthors() {
     var pubspec = entrypoint.root.pubspec;
     var author = pubspec.fields['author'];
     var authors = pubspec.fields['authors'];
     if (author == null && authors == null) {
       errors.add('Your pubspec.yaml must have an "author" or "authors" field.');
-    } else {
-      if (authors == null) authors = [author];
-
-      var hasName = new RegExp(r"^ *[^< ]");
-      var hasEmail = new RegExp(r"<[^>]+> *$");
-      for (var authorName in authors) {
-        if (!hasName.hasMatch(authorName)) {
-          warnings.add('Author "$authorName" in pubspec.yaml should have a '
-              'name.');
-        }
-        if (!hasEmail.hasMatch(authorName)) {
-          warnings.add('Author "$authorName" in pubspec.yaml should have an '
-              'email address\n(e.g. "name <email>").');
-        }
-      }
+      return;
+    }
+
+    if (author != null && author is! String) {
+      errors.add('Your pubspec.yaml\'s "author" field must be a string, but it '
+          'was "$author".');
+      return;
     }
 
-    var homepage = pubspec.fields['homepage'];
-    if (homepage == null) {
-      errors.add('Your pubspec.yaml is missing a "homepage" field.');
+    if (authors != null &&
+        (authors is! List || authors.any((author) => author is! String))) {
+      errors.add('Your pubspec.yaml\'s "authors" field must be a string, but '
+          'it was "$authors".');
+      return;
     }
 
-    var description = pubspec.fields['description'];
-    if (description == null) {
-      errors.add('Your pubspec.yaml is missing a "description" field.');
+    if (authors == null) authors = [author];
+
+    var hasName = new RegExp(r"^ *[^< ]");
+    var hasEmail = new RegExp(r"<[^>]+> *$");
+    for (var authorName in authors) {
+      if (!hasName.hasMatch(authorName)) {
+        warnings.add('Author "$authorName" in pubspec.yaml should have a '
+            'name.');
+      }
+      if (!hasEmail.hasMatch(authorName)) {
+        warnings.add('Author "$authorName" in pubspec.yaml should have an '
+            'email address\n(e.g. "name <email>").');
+      }
+    }
+  }
+
+  /// Adds an error if [field] doesn't exist or isn't a string.
+  void _validateFieldIsString(String field) {
+    var value = entrypoint.root.pubspec.fields[field];
+    if (value == null) {
+      errors.add('Your pubspec.yaml is missing a "$field" field.');
+    } else if (value is! String) {
+      errors.add('Your pubspec.yaml\'s "$field" field must be a string, but '
+          'it was "$value".');
     }
+  }
+
+  /// Adds an error if the URL for [field] is invalid.
+  void _validateFieldUrl(String field) {
+    var url = entrypoint.root.pubspec.fields[field];
+    if (url == null) return;
 
-    var version = pubspec.fields['version'];
-    if (version == null) {
-      errors.add('Your pubspec.yaml is missing a "version" field.');
+    if (url is! String) {
+      errors.add('Your pubspec.yaml\'s "$field" field must be a string, but '
+          'it was "$url".');
+      return;
     }
 
-    return new Future.value();
+    var goodScheme = new RegExp(r'^https?:');
+    if (!goodScheme.hasMatch(url)) {
+      errors.add('Your pubspec.yaml\'s "$field" field must be an "http:" or '
+          '"https:" URL, but it was "$url".');
+    }
   }
 }