Convert value from caproto type to Python types

common.py

@@ -4,6 +4,33 @@ import os
 import pytest
 import yaml
 from caproto.sync.client import read, write
+from caproto import CaprotoTimeoutError, ChannelType
+
+FTYPE_TO_TYPE = {
+    ChannelType.STRING: str,
+    ChannelType.INT: int,
+    ChannelType.FLOAT: float,
+    ChannelType.ENUM: int,
+    ChannelType.CHAR: bytes,
+    ChannelType.LONG: int,
+    ChannelType.DOUBLE: float,
+
+    ChannelType.TIME_STRING: str,
+    ChannelType.TIME_INT: int,
+    ChannelType.TIME_FLOAT: float,
+    ChannelType.TIME_ENUM: int,
+    ChannelType.TIME_CHAR: bytes,
+    ChannelType.TIME_LONG: int,
+    ChannelType.TIME_DOUBLE: float,
+
+    ChannelType.CTRL_STRING: str,
+    ChannelType.CTRL_INT: int,
+    ChannelType.CTRL_FLOAT: float,
+    ChannelType.CTRL_ENUM: int,
+    ChannelType.CTRL_CHAR: bytes,
+    ChannelType.CTRL_LONG: int,
+    ChannelType.CTRL_DOUBLE: float,
+}
 
 
 def read_config():
@@ -16,7 +43,7 @@ class MajorState(Exception):
     pass
 
 
-class Axis:
+class Motor:
 
     # Motor record fields
     fields = {
@@ -60,11 +87,38 @@ class Axis:
     def write_field(self, fieldname, value):
         self.write('.' + self.fields[fieldname], value)
 
-    def read(self, suffix):
-        return read(self.pv + suffix).data
+    def read(self, suffix, as_string=False):
+        response = read(self.pv + suffix).data
+        return self._convert_value(response, as_string)
 
-    def read_field(self, fieldname):
-        return self.read('.' + self.fields[fieldname])
+    def _convert_value(self, response, as_string=False):
+
+        # By default, the response data is always a list to cover all possible
+        # readback values from EPICS (lists, strings, chars, numbers). The last
+        # two cases need to be treated in a special way. They can be identified
+        # by the list length being 1.
+        if len(response.data) == 1:
+            value = response.data[0]
+            if isinstance(value, bytes):
+                return value.decode()
+
+            # If an empty string is returned, the data has a single entry
+            # (the NULL terminator)
+            if as_string:
+                return bytes(response.data).rstrip(b'\x00').decode(
+                    encoding='utf-8', errors='ignore')
+
+            return value
+
+        # Strings are read with their NULL terminator, hence it needs to be
+        # stripped before decoding
+        if as_string:
+            return bytes(response.data).rstrip(b'\x00').decode(
+                encoding='utf-8', errors='ignore')
+        return response.data
+
+    def read_field(self, fieldname, as_string=False):
+        return self.read('.' + self.fields[fieldname], as_string)
 
     def move_and_wait(self, target):
         """
@@ -107,7 +161,7 @@ class Axis:
         return bool(str[15])
 
 
-class SinqMotor(Axis):
+class SinqMotor(Motor):
     # PV suffixes used in SinqMotor drivers
     suffixes = {
         'enable': ':Enable',
@@ -130,5 +184,5 @@ class SinqMotor(Axis):
         return self.read('.' + self.fields[fieldname])
 
 
-class TurboPMAC(Axis):
+class TurboPMAC(SinqMotor):
     pass