Merge #11291: Fix string concatenation to os.path.join and add exception case

a3ac7672ed Fix string concatenation to os.path.join and add exception case (dongsamb)

Pull request description:

  Solved some warnings for [Python PEP 8 convention](https://www.python.org/dev/peps/pep-0008/)

  - [Method Names and Instance Variables](https://www.python.org/dev/peps/pep-0008/#method-names-and-instance-variables)
  lowercase with words separated by underscores as necessary to improve readability.

      - `testDir` to `test_dir`
      - `inputData` to `input_data`
      - ...

  - [Blank Lines](https://www.python.org/dev/peps/pep-0008/#blank-lines)
  Surround top-level function and class definitions with two blank lines.

  - [Exception Names](https://www.python.org/dev/peps/pep-0008/#exception-names)

  and added verification logic about referenced before assignment for `output_type`

Tree-SHA512: 346d08799f03077a2b7257ccdca123b4945b89dbf0677dba452d96b81ce186ec7b5dcdb10b8bb59cfce657a7aedbb7df64921036cbd1bf4ad8bd313d40faa796

test/util/bitcoin-util-test.py

@@ -48,7 +48,7 @@ def main():
 
 def bctester(testDir, input_basename, buildenv):
     """ Loads and parses the input file, runs all tests and reports results"""
-    input_filename = testDir + "/" + input_basename
+    input_filename = os.path.join(testDir, input_basename)
     raw_data = open(input_filename).read()
     input_data = json.loads(raw_data)
 
@@ -77,7 +77,7 @@ def bctest(testDir, testObj, buildenv):
     are not as expected. Error is caught by bctester() and reported.
     """
     # Get the exec names and arguments
-    execprog = buildenv["BUILDDIR"] + "/src/" + testObj['exec'] + buildenv["EXEEXT"]
+    execprog = os.path.join(buildenv["BUILDDIR"], "src", testObj["exec"] + buildenv["EXEEXT"])
     execargs = testObj['args']
     execrun = [execprog] + execargs
 
@@ -85,24 +85,28 @@ def bctest(testDir, testObj, buildenv):
     stdinCfg = None
     inputData = None
     if "input" in testObj:
-        filename = testDir + "/" + testObj['input']
+        filename = os.path.join(testDir, testObj["input"])
         inputData = open(filename).read()
         stdinCfg = subprocess.PIPE
 
     # Read the expected output data (if there is any)
     outputFn = None
     outputData = None
+    outputType = None
     if "output_cmp" in testObj:
         outputFn = testObj['output_cmp']
         outputType = os.path.splitext(outputFn)[1][1:]  # output type from file extension (determines how to compare)
         try:
-            outputData = open(testDir + "/" + outputFn).read()
+            outputData = open(os.path.join(testDir, outputFn)).read()
         except:
             logging.error("Output file " + outputFn + " can not be opened")
             raise
         if not outputData:
             logging.error("Output data missing for " + outputFn)
             raise Exception
+        if not outputType:
+            logging.error("Output file %s does not have a file extension" % outputFn)
+            raise Exception
 
     # Run the test
     proc = subprocess.Popen(execrun, stdin=stdinCfg, stdout=subprocess.PIPE, stderr=subprocess.PIPE, universal_newlines=True)