ctexplain: make cquery parsing more robust.

Specifically:

 - Handle labels with spaces
 - Handle targets with no fragment requirements.

These were both inspired by real analyses.

Testing: $ bazel test //tools/ctexplain:all
Work towards bazelbuild#10613

tools/ctexplain/bazel_api.py

@@ -43,7 +43,7 @@ def run_bazel_in_client(args: List[str]) -> Tuple[int, List[str], List[str]]:
     Tuple of (return code, stdout, stderr)
   """
   result = subprocess.run(
-      ["blaze"] + args,
+      ["bazel"] + args,
       cwd=os.getcwd(),
       stdout=subprocess.PIPE,
       stderr=subprocess.PIPE,
@@ -145,20 +145,27 @@ def _parse_cquery_result_line(line: str) -> ConfiguredTarget:
   Returns:
     Corresponding ConfiguredTarget if the line matches else None.
   """
-  tokens = line.split(maxsplit=2)
-  label = tokens[0]
-  if tokens[1][0] != "(" or tokens[1][-1] != ")":
-    raise ValueError(f"{tokens[1]} in {line} not surrounded by parentheses")
-  config_hash = tokens[1][1:-1]
+  config_hash_start = line.find("(")
+  config_hash_end = line.find(")", config_hash_start)
+  fragments_start = line.find("[", config_hash_end)
+  fragments_end = line.find("]", fragments_start)
+
+  label = line[0:config_hash_start].strip()
+  if config_hash_start == -1 or config_hash_end < config_hash_start:
+    raise ValueError(f'"{line}": no "(<config hash>)" suffix')
+  config_hash = line[config_hash_start + 1:config_hash_end]
   if config_hash == "null":
     fragments = ()
   else:
-    if tokens[2][0] != "[" or tokens[2][-1] != "]":
-      raise ValueError(f"{tokens[2]} in {line} not surrounded by [] brackets")
+    if fragments_start == -1 or fragments_end < fragments_start:
+      raise ValueError(f'"{line}": no "[<required fragment>, ...]" suffix')
     # The fragments list looks like '[Fragment1, Fragment2, ...]'. Split the
     # whole line on ' [' to get just this list, then remove the final ']', then
     # split again on ', ' to convert it to a structured tuple.
-    fragments = tuple(line.split(" [")[1][0:-1].split(", "))
+    if fragments_start == fragments_end - 1:
+      fragments = tuple()
+    else:
+      fragments = tuple(line[fragments_start + 1:fragments_end].split(", "))
   return ConfiguredTarget(
       label=label,
       config=None,  # Not yet available: we'll need `bazel config` to get this.

tools/ctexplain/bazel_api_test.py

@@ -45,7 +45,7 @@ def testBasicCquery(self):
     self.assertEqual(len(cts), 1)
     self.assertEqual(cts[0].label, '//testapp:fg')
     self.assertIsNone(cts[0].config)
-    self.assertGreater(len(cts[0].config_hash), 10)
+    self.assertGreater(len(cts[0].config_hash), 6)
     self.assertIn('PlatformConfiguration', cts[0].transitive_fragments)
 
   def testFailedCquery(self):
@@ -144,14 +144,38 @@ def testConfigWithStarlarkFlags(self):
         'string_flag(name = "my_flag", build_setting_default = "nada")',
         'filegroup(name = "fg", srcs = ["a.file"])',
     ])
-    cquery_args = ['//testapp:fg', '--//testapp:my_flag', 'algo']
+    cquery_args = ['//testapp:fg', '--//testapp:my_flag=algo']
     cts = self._bazel_api.cquery(cquery_args)[2]
     config = self._bazel_api.get_config(cts[0].config_hash)
     user_defined_options = config.options['user-defined']
     self.assertIsNotNone(user_defined_options)
     self.assertDictEqual(user_defined_options._dict,
                          {'//testapp:my_flag': 'algo'})
 
+  def testLabelsWithSpaces(self):
+    self.ScratchFile('testapp/BUILD', [
+        'filegroup(name = "labels can have spaces", srcs = ["a.file"])',
+    ])
+    cquery_args = ['//testapp:labels can have spaces']
+    res = self._bazel_api.cquery(['//testapp:all'])
+    success = res[0]
+    cts = res[2]
+    self.assertTrue(success)
+    self.assertEqual(len(cts), 1)
+    self.assertEqual(cts[0].label, '//testapp:labels can have spaces')
+
+  def testEmptyFragmentRequirements(self):
+    self.ScratchFile('testapp/BUILD', [
+        'alias(name = "alias_to_src", actual = "source.file")',
+    ])
+    cquery_args = ['//testapp:alias_to_src']
+    res = self._bazel_api.cquery(['//testapp:all'])
+    success = res[0]
+    cts = res[2]
+    self.assertTrue(success)
+    self.assertEqual(len(cts), 1)
+    self.assertEqual(cts[0].label, '//testapp:alias_to_src')
+    self.assertEqual(len(cts[0].transitive_fragments), 0)
 
 if __name__ == '__main__':
   unittest.main()