command: fixup parsing of stale query parameter (#15654)

In #15605 we fixed the bug where the presense of "stale" query parameter
was mean to imply stale, even if the value of the parameter was "false"
or malformed. In parsing, we missed the case where the slice of values
would be nil which lead to a failing test case that was missed because
CI didn't run against the original PR.

Co-authored-by: Seth Hoenig <shoenig@duck.com>

command/agent/http.go

@@ -709,13 +709,17 @@ func parseWait(resp http.ResponseWriter, req *http.Request, b *structs.QueryOpti
 func parseConsistency(resp http.ResponseWriter, req *http.Request, b *structs.QueryOptions) {
 	query := req.URL.Query()
 	if staleVal, ok := query["stale"]; ok {
+		if len(staleVal) == 0 || staleVal[0] == "" {
+			b.AllowStale = true
+			return
+		}
 		staleQuery, err := strconv.ParseBool(staleVal[0])
 		if err != nil {
 			resp.WriteHeader(400)
-			resp.Write([]byte(fmt.Sprintf("Expect `true` or `false` for `stale` query string parameter, got %s", staleVal[0])))
+			_, _ = resp.Write([]byte(fmt.Sprintf("Expect `true` or `false` for `stale` query string parameter, got %s", staleVal[0])))
+			return
 		}
-
-		b.AllowStale = staleQuery || staleVal[0] == ""
+		b.AllowStale = staleQuery
 	}
 }
 

command/operator_debug_test.go

@@ -56,6 +56,7 @@ func runTestCases(t *testing.T, cases testCases) {
 			require.Equalf(t, code, c.expectedCode, "expected exit code %d, got: %d: %s", c.expectedCode, code, outerr)
 			for _, expectedOutput := range c.expectedOutputs {
 				require.Contains(t, out, expectedOutput, "expected output %q, got %q", expectedOutput, out)
+
 			}
 			require.Containsf(t, outerr, c.expectedError, "expected error %q, got %q", c.expectedError, outerr)
 		})