standardise all validate tests

chars_test.go

@@ -4,32 +4,26 @@ import "testing"
 
 func TestChars(t *testing.T) {
 	type TestCase struct {
-		C     string
 		Input string
-		Err   bool
+		C     string
+		Err   error
 	}
 
 	hexRange := "0123456789abcdef"
 
 	testCases := []TestCase{
-		{C: hexRange, Input: "abcd1234"},
-		{C: hexRange, Input: "abcd 1234", Err: true},
+		{Input: "abcd1234", C: hexRange},
+		{Input: "abcd 1234", C: hexRange, Err: ErrDisallowedChars},
 	}
 
 	for _, tc := range testCases {
-		t.Logf("%q contains only allowed characters %q", tc.Input, tc.C)
+		t.Logf("Testing %q against %q", tc.Input, tc.C)
 
 		f := Chars(tc.C)
 		err := f(tc.Input)
 
-		if tc.Err {
-			if err == nil {
-				t.Error("Expected error; got nil")
-			}
-		} else {
-			if err != nil {
-				t.Errorf("Expected nil; got %s", err)
-			}
+		if err != tc.Err {
+			t.Errorf("Expected error %v, got %v", tc.Err, err)
 		}
 	}
 }