Merge #12878: [refactor] Config handling refactoring in preparation for network-specific sections

77a733a99 [tests] Add additional unit tests for -nofoo edge cases (Anthony Towns)
af173c2be [tests] Check GetChainName works with config entries (Anthony Towns)
fa27f1c23 [tests] Add unit tests for ReadConfigStream (Anthony Towns)
087c5d204 ReadConfigStream: assume the stream is good (Anthony Towns)
6d5815aad Separate out ReadConfigStream from ReadConfigFile (Anthony Towns)
834d30341 [tests] Add unit tests for GetChainName (Anthony Towns)
11b6b5b86 Move ChainNameFromCommandLine into ArgsManager and rename to GetChainName (Anthony Towns)

Pull request description:

  This does a bit of refactoring of the configuration handling code in order to add additional tests to make adding support for [test]/[regtest] sections in the config file in #11862 easier. Should not cause any behaviour changes.

Tree-SHA512: 8d2ce1449fc180de03414e7e569d1a21ba1e9f6564e13d3faf3961f710adc725fa0d4ab49b89ebd2baa11ea36ac5018377f693a84037d386a8b8697c9d6db3e9

src/util.h

@@ -228,6 +228,8 @@ protected:
     std::map<std::string, std::vector<std::string>> mapMultiArgs;
     std::unordered_set<std::string> m_negated_args;
 
+    void ReadConfigStream(std::istream& stream);
+
 public:
     void ParseParameters(int argc, const char*const argv[]);
     void ReadConfigFile(const std::string& confPath);
@@ -306,6 +308,12 @@ public:
     // been set. Also called directly in testing.
     void ForceSetArg(const std::string& strArg, const std::string& strValue);
 
+    /**
+     * Looks for -regtest, -testnet and returns the appropriate BIP70 chain name.
+     * @return CBaseChainParams::MAIN by default; raises runtime error if an invalid combination is given.
+     */
+    std::string GetChainName() const;
+
 private:
 
     // Munge -nofoo into -foo=0 and track the value as negated.