add fix for uppercase testing

previously it would only match a string that was only uppercase characters.
this fix allows a string to have non-uppercasable characters as long as
there is at least one uppercase character

a simple testcase has also been added

docopt.go

@@ -1203,11 +1203,16 @@ func stringPartition(s, sep string) (string, string, string) {
 	return split[0], sep, split[1]
 }
 
+// returns true if all cased characters in the string are uppercase
+// and there are there is at least one cased charcter
 func isStringUppercase(s string) bool {
-	for _, c := range s {
-		if !unicode.IsUpper(c) {
-			return false
-		}
-	}
-	return true
+    if strings.ToUpper(s) != s {
+        return false
+    }
+    for _, c := range []rune(s) {
+        if unicode.IsUpper(c) {
+            return true
+        }
+    }
+    return false
 }

docopt_test.go

@@ -1424,6 +1424,33 @@ func TestFileTestcases(t *testing.T) {
 	}
 }
 
+func TestFileTestcasesGo(t *testing.T) {
+    filename := "test_golang.docopt"
+    file, err := os.Open(filename)
+    if err != nil {
+        t.Fatal(err)
+    }
+    defer file.Close()
+
+    for c := range parseTest(file) {
+        if c.err != nil {
+            t.Fatal(err)
+            break
+        }
+        result, _, err := Parse(c.doc, c.argv, true, "", false)
+        if _, ok := err.(*UserError); c.userError && !ok {
+            // expected a user-error
+            t.Error("testcase:", c.id, "result:", result)
+        } else if _, ok := err.(*UserError); !c.userError && ok {
+            // unexpected user-error
+            t.Error("testcase:", c.id, "error:", err, "result:", result)
+        } else if reflect.DeepEqual(c.expect, result) != true {
+            t.Error("testcase:", c.id, "result:", result)
+        }
+    }
+}
+
+
 type testcase struct {
 	id        int
 	doc       string

test_golang.docopt

@@ -0,0 +1,9 @@
+r"""usage: prog [NAME_-2]..."""
+$ prog 10 20
+{"NAME_-2": ["10", "20"]}
+
+$ prog 10
+{"NAME_-2": ["10"]}
+
+$ prog
+{"NAME_-2": []}