Function TestEndToEnd_logfmt

log/sanitize_test.go:289–357

TestEndToEnd_logfmt verifies that values wrapped with DropUnsafeChars or EscapeUnsafeChars are encoded as expected by go-kit's logfmt logger.

(t *testing.T)

// DropUnsafeChars or EscapeUnsafeChars are encoded as expected by
// go-kit's logfmt logger.
func TestEndToEnd_logfmt(t *testing.T) {
	testCases := map[string]struct {
		value      any
		wantOnWire map[string]string // logger name -> expected bytes
	}{
		"clean string passes through both wrappers unchanged": {
			value: "Mozilla/5.0",
			wantOnWire: map[string]string{
				"drop":   "user_agent=Mozilla/5.0\n",
				"escape": "user_agent=Mozilla/5.0\n",
			},
		},
		"embedded newline is sanitized before reaching the encoder": {
			value: "Mozilla\nFAKE",
			wantOnWire: map[string]string{
				// Drop yields "MozillaFAKE". Because the result contains no whitespace,
				// logfmt emits it without quotes.
				"drop": "user_agent=MozillaFAKE\n",
				// Escape yields "Mozilla\x0aFAKE" (with a literal backslash). Because
				// the result contains no whitespace, logfmt does not quote it and it
				// reaches the output unchanged.
				"escape": "user_agent=Mozilla\\x0aFAKE\n",
			},
		},
		"custom Stringer rendering user-controlled text is sanitized": {
			value: testUnsafeUserInputStringer{"path=/foo\nFAKE"},
			wantOnWire: map[string]string{
				// Drop yields "path=/fooFAKE". Because the value contains '=',
				// logfmt quotes it in the output.
				"drop": "user_agent=\"path=/fooFAKE\"\n",
				// Escape yields "path=/foo\x0aFAKE". The embedded '=' causes logfmt to
				// quote the value, and the backslash in `\x0a` is escaped within the
				// quoted string.
				"escape": "user_agent=\"path=/foo\\\\x0aFAKE\"\n",
			},
		},
		"typed-nil error renders as null, matching go-kit raw output": {
			value: (*testNilSafeError)(nil),
			wantOnWire: map[string]string{
				"drop":   "user_agent=null\n",
				"escape": "user_agent=null\n",
			},
		},
		"nil any renders as null, matching go-kit raw output": {
			value: nil,
			wantOnWire: map[string]string{
				"drop":   "user_agent=null\n",
				"escape": "user_agent=null\n",
			},
		},
	}

	for name, tc := range testCases {
		t.Run(name, func(t *testing.T) {
			t.Run("drop", func(t *testing.T) {
				buf := &bytes.Buffer{}
				logger := log.NewLogfmtLogger(buf)
				require.NoError(t, logger.Log("user_agent", DropUnsafeChars(tc.value)))