adding ref mat'l, Service tests done

.ref/URLs

@@ -7,3 +7,7 @@ https://people.gnome.org/~stefw/libsecret-docs/index.html
 Quick reference URLs:
 
 Dbus paths: https://specifications.freedesktop.org/secret-service/latest/ch12.html
+Message types: https://dbus.freedesktop.org/doc/dbus-specification.html#type-system
+	Use this for reference for errors like:
+		Type of message, “(ao)”, does not match expected type “(aoo)”
+	See dbus_types subdir for Golang structs that can be used in the future to improve these error messages.

.ref/dbus_types/structs.go

@@ -0,0 +1,116 @@
+package dbus_types
+
+// https://dbus.freedesktop.org/doc/dbus-specification.html#type-system
+
+type DbusType struct {
+	TypeName  string
+	Symbol    rune
+	Desc      string
+	ZeroValue interface{}
+}
+
+/*
+	BASIC TYPES
+*/
+
+var DbusByte DbusType = DbusType{
+	TypeName:  "BYTE",
+	Symbol:    'y',
+	Desc:      "Unsigned 8-bit integer",
+	ZeroValue: byte(0x0),
+}
+
+var DbusBoolean DbusType = DbusType{
+	TypeName:  "BOOLEAN",
+	Symbol:    'b',
+	Desc:      "Boolean value: 0 is false, 1 is true, any other value allowed by the marshalling format is invalid",
+	ZeroValue: false,
+}
+
+var DbusInt16 DbusType = DbusType{
+	TypeName:  "INT16",
+	Symbol:    'n',
+	Desc:      "Signed (two's complement) 16-bit integer",
+	ZeroValue: int16(0),
+}
+
+var DbusUint16 DbusType = DbusType{
+	TypeName:  "UINT16",
+	Symbol:    'q',
+	Desc:      "Unsigned 16-bit integer",
+	ZeroValue: uint16(0),
+}
+
+var DbusInt32 DbusType = DbusType{
+	TypeName:  "INT32",
+	Symbol:    'i',
+	Desc:      "Signed (two's complement) 32-bit integer",
+	ZeroValue: int32(0),
+}
+
+var DbusUint32 DbusType = DbusType{
+	TypeName:  "UINT32",
+	Symbol:    'u',
+	Desc:      "Unsigned 32-bit integer",
+	ZeroValue: uint32(0),
+}
+
+var DbusInt64 DbusType = DbusType{
+	TypeName:  "INT64",
+	Symbol:    'x',
+	Desc:      "Signed (two's complement) 64-bit integer (mnemonic: x and t are the first characters in \"sixty\" not already used for something more common)",
+	ZeroValue: int64(0),
+}
+
+var DbusUint64 DbusType = DbusType{
+	TypeName:  "UINT64",
+	Symbol:    't',
+	Desc:      "Unsigned 64-bit integer",
+	ZeroValue: uint64(0),
+}
+
+var DbusDoubleFloat DbusType = DbusType{
+	TypeName:  "DOUBLE",
+	Symbol:    'd',
+	Desc:      "IEEE 754 double-precision floating point",
+	ZeroValue: float64(0),
+}
+
+var DbusUnixFD DbusType = DbusType{
+	TypeName:  "UNIX_FD",
+	Symbol:    'h',
+	Desc:      "Unsigned 32-bit integer representing an index into an out-of-band array of file descriptors, transferred via some platform-specific mechanism (mnemonic: h for handle)",
+	ZeroValue: uint32(0), // See https://pkg.go.dev/github.com/godbus/dbus#UnixFDIndex
+}
+
+var DbusString DbusType = DbusType{
+	TypeName:  "STRING",
+	Symbol:    'o',
+	Desc:      "No extra constraints",
+	ZeroValue: "",
+}
+
+var DbusObjectPath DbusType = DbusType{
+	TypeName:  "OBJECT_PATH",
+	Symbol:    'o',
+	Desc:      "A syntactically valid Path for Dbus",
+	ZeroValue: nil, // ???
+}
+
+var DbusSignature DbusType = DbusType{
+	TypeName:  "SIGNATURE",
+	Symbol:    'g',
+	Desc:      "0 or more single complete types", // ???
+	ZeroValue: nil,                               // ???
+}
+
+/*
+	CONTAINER TYPES
+*/
+/*
+	TODO: not sure how to struct this natively, but:
+		  Dbus Struct:  (<symbol(s)...>) // Note: structs can be nested e.g. (i(ii))
+		  Dbus Array:   a<symbol>		 // The symbol can be any type (even nested arrays, e.g. aai), but only one type is allowed. Arrays are like Golang slices; no fixed size.
+		  Dbus Variant: v<symbol>		 // Dbus equivalent of interface{}, more or less. See https://dbus.freedesktop.org/doc/dbus-specification.html#container-types
+		  Dbus Dict:    [kv]			 // Where k is the key's type and v is the value's type.
+*/