test(promslog): refactor to set style via exposed Set() method

Previously this was cheating and setting the internal value of the style
because it's in the same package, but consumers of this library
obviously can't do that. To test the same usage flow as users, this
switches tests to use the Set() method when setting logging style in
tests.

Signed-off-by: TJ Hoplock <[email protected]>

Author: tjhop

promslog/slog_test.go

@@ -21,6 +21,7 @@ import (
 	"fmt"
 	"log/slog"
 	"regexp"
+	"slices"
 	"strings"
 	"testing"
 
@@ -114,7 +115,17 @@ func TestDynamicLevels(t *testing.T) {
 	for name, tc := range tests {
 		t.Run(name, func(t *testing.T) {
 			buf.Reset() // Ensure buf is reset prior to tests
-			config := &Config{ioWriter: &buf, Style: &AllowedStyle{s: tc.logStyle}}
+			config := &Config{ioWriter: &buf, Style: &AllowedStyle{}}
+			err := config.Style.Set(tc.logStyle)
+			// AllowedStyle.Set() returns an error on invalid style
+			// values and the tests use a mixture of valid and
+			// invalid values. We must expect no error for valid
+			// values, and expect an error for the invalid values.
+			if slices.Contains(StyleOptions, tc.logStyle) {
+				require.NoError(t, err, "log style returned an error setting a valid value", "value", tc.logStyle)
+			} else {
+				require.ErrorContains(t, err, fmt.Sprintf("unrecognized log style %s", tc.logStyle), "expected error setting log style to invalid value", "value", tc.logStyle)
+			}
 			logger := New(config)
 
 			// Test that log level can be adjusted on-the-fly to debug and that a