From fe1637c2236e6d0157898ba8166377d99b3671a5 Mon Sep 17 00:00:00 2001
From: Jonathan Moody <103143855+moodyjon@users.noreply.github.com>
Date: Wed, 20 Apr 2022 10:33:36 -0400
Subject: [PATCH] [lbry] config: Verify completeness of sample-lbcd.conf using
 reflection on config struct.

---
 config_test.go | 104 +++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 104 insertions(+)

diff --git a/config_test.go b/config_test.go
index 84e7d444..15953b15 100644
--- a/config_test.go
+++ b/config_test.go
@@ -1,9 +1,11 @@
 package main
 
 import (
+	"fmt"
 	"io/ioutil"
 	"os"
 	"path/filepath"
+	"reflect"
 	"regexp"
 	"runtime"
 	"testing"
@@ -14,6 +16,108 @@ var (
 	rpcpassRegexp = regexp.MustCompile("(?m)^rpcpass=.+$")
 )
 
+// Define a struct "configCmdLineOnly" containing a subset of configuration
+// parameters which are command-line only. These fields are copied line-by-line
+// from "config" struct in "config.go", and the field names, types, and tags must
+// match for the test to work.
+//
+type configCmdLineOnly struct {
+	ConfigFile          string   `short:"C" long:"configfile" description:"Path to configuration file"`
+	DbType              string   `long:"dbtype" description:"Database backend to use for the Block Chain"`
+	DropCfIndex         bool     `long:"dropcfindex" description:"Deletes the index used for committed filtering (CF) support from the database on start up and then exits."`
+	DropTxIndex         bool     `long:"droptxindex" description:"Deletes the hash-based transaction index from the database on start up and then exits."`
+	DisableCheckpoints  bool     `long:"nocheckpoints" description:"Disable built-in checkpoints.  Don't do this unless you know what you're doing."`
+	NoWinService        bool     `long:"nowinservice" description:"Do not start as a background service on Windows -- NOTE: This flag only works on the command line, not in the config file"`
+	DisableStallHandler bool     `long:"nostalldetect" description:"Disables the stall handler system for each peer, useful in simnet/regtest integration tests frameworks"`
+	RegressionTest      bool     `long:"regtest" description:"Use the regression test network"`
+	SimNet              bool     `long:"simnet" description:"Use the simulation test network"`
+	SigNet              bool     `long:"signet" description:"Use the signet test network"`
+	SigNetChallenge     string   `long:"signetchallenge" description:"Connect to a custom signet network defined by this challenge instead of using the global default signet test network -- Can be specified multiple times"`
+	SigNetSeedNode      []string `long:"signetseednode" description:"Specify a seed node for the signet network instead of using the global default signet network seed nodes"`
+	ShowVersion         bool     `short:"V" long:"version" description:"Display version information and exit"`
+}
+
+func fieldEq(f1, f2 reflect.StructField) bool {
+	return (f1.Name == f2.Name) && (f1.Type == f2.Type) && (f1.Tag == f2.Tag)
+}
+
+func TestSampleConfigFileComplete(t *testing.T) {
+	// find out where the sample config lives
+	_, path, _, ok := runtime.Caller(0)
+	if !ok {
+		t.Fatalf("Failed finding config file path")
+	}
+	sampleConfigFile := filepath.Join(filepath.Dir(path), sampleConfigFilename)
+
+	// Read the sample config file
+	content, err := ioutil.ReadFile(sampleConfigFile)
+	if err != nil {
+		t.Fatalf("Failed reading sample config file: %v", err)
+	}
+
+	allFields := reflect.VisibleFields(reflect.TypeOf(config{}))
+	cmdlineFields := reflect.VisibleFields(reflect.TypeOf(configCmdLineOnly{}))
+
+	// Verify cmdlineFields is a subset of allFields.
+	for _, cf := range cmdlineFields {
+		// Check for presence of field "cf" in config struct.
+		var field *reflect.StructField
+		for _, f := range allFields {
+			f := f // new instance of loop var for return
+			if fieldEq(cf, f) {
+				field = &f
+				break
+			}
+		}
+		if field == nil {
+			t.Errorf("cmdline field: %s type: %s is not present in type %s",
+				cf.Name, cf.Type, reflect.TypeOf(config{}))
+		}
+	}
+
+	// Verify sample config covers all parameters.
+	for _, f := range allFields {
+		longname, ok := f.Tag.Lookup("long")
+		if !ok {
+			// Field has no long-form name, so not eligible for
+			// inclusion in sample config.
+			continue
+		}
+
+		// Check for presence of field "f" in our configCmdLineOnly struct.
+		var cmdline *reflect.StructField
+		for _, cf := range cmdlineFields {
+			cf := cf // new instance of loop var for return
+			if fieldEq(cf, f) {
+				cmdline = &cf
+				break
+			}
+		}
+
+		// Look for assignment (<longname>="), or commented assignment ("; <longname>=").
+		pattern := fmt.Sprintf("(?m)^(;\\s*)?%s=.*$", longname)
+		assignment, err := regexp.Compile(pattern)
+		if err != nil {
+			t.Errorf("config field: %s longname: %s failed compiling regexp (%s): %v",
+				f.Name, longname, pattern, err)
+			continue
+		}
+
+		assigned := assignment.Match(content)
+
+		// Field "f" must be present in either the sample config (<longname>=X),
+		// or it must be one of the command line only fields, but not both.
+		if !assigned && (cmdline == nil) {
+			t.Errorf("config field: %s longname: %s assignment (%s) should be present in %s",
+				f.Name, longname, assignment, sampleConfigFilename)
+		}
+		if assigned && (cmdline != nil) {
+			t.Errorf("config field: %s longname: %s should not be present in both %s and type %s",
+				f.Name, longname, sampleConfigFilename, reflect.TypeOf(configCmdLineOnly{}).Name())
+		}
+	}
+}
+
 func TestCreateDefaultConfigFile(t *testing.T) {
 	// find out where the sample config lives
 	_, path, _, ok := runtime.Caller(0)