Validate specification names

This will validate that specification names are restricted to those that rubygems.org will accept, and provide a superior experience when users accidentally include invalid characters in the name compared to an invalid push or a failing install

Author: segiddins

lib/rubygems/specification.rb

@@ -108,6 +108,8 @@ class Gem::Specification < Gem::BasicSpecification
 
   private_constant :LOAD_CACHE if defined? private_constant
 
+  VALID_NAME_PATTERN = /\A[a-zA-Z0-9\.\-\_]+\z/ # :nodoc:
+
   # :startdoc:
 
   ##
@@ -2668,9 +2670,15 @@ def validate packaging = true
       end
     end
 
-    unless String === name then
+    if !name.is_a?(String) then
+      raise Gem::InvalidSpecificationException,
+            "invalid value for attribute name: \"#{name.inspect}\" must be a string"
+    elsif name !~ /[a-zA-Z]/ then
+      raise Gem::InvalidSpecificationException,
+            "invalid value for attribute name: #{name.dump} must include at least one letter"
+    elsif name !~ VALID_NAME_PATTERN then
       raise Gem::InvalidSpecificationException,
-            "invalid value for attribute name: \"#{name.inspect}\""
+            "invalid value for attribute name: #{name.dump} can only include letters, numbers, dashes, and underscores"
     end
 
     if raw_require_paths.empty? then

test/rubygems/test_gem_specification.rb

@@ -2985,7 +2985,37 @@ def test_validate_name
       @a1.validate
     end
 
-    assert_equal 'invalid value for attribute name: ":json"', e.message
+    assert_equal 'invalid value for attribute name: ":json" must be a string', e.message
+
+    @a1.name = []
+    e = assert_raises Gem::InvalidSpecificationException do
+      @a1.validate
+    end
+    assert_equal "invalid value for attribute name: \"[]\" must be a string", e.message
+
+    @a1.name = ""
+    e = assert_raises Gem::InvalidSpecificationException do
+      @a1.validate
+    end
+    assert_equal "invalid value for attribute name: \"\" must include at least one letter", e.message
+
+    @a1.name = "12345"
+    e = assert_raises Gem::InvalidSpecificationException do
+      @a1.validate
+    end
+    assert_equal "invalid value for attribute name: \"12345\" must include at least one letter", e.message
+
+    @a1.name = "../malicious"
+    e = assert_raises Gem::InvalidSpecificationException do
+      @a1.validate
+    end
+    assert_equal "invalid value for attribute name: \"../malicious\" can only include letters, numbers, dashes, and underscores", e.message
+
+    @a1.name = "\ba\t"
+    e = assert_raises Gem::InvalidSpecificationException do
+      @a1.validate
+    end
+    assert_equal "invalid value for attribute name: \"\\ba\\t\" can only include letters, numbers, dashes, and underscores", e.message
   end
 
   def test_validate_non_nil