Add enum for LintIssue severity

docs/plugins.rst

@@ -144,6 +144,7 @@ Example Rule
 .. code-block:: python
 
    import squabble.rule
+   from squabble.lint import Severity
    from squabble.message import Message
    from squabble.rules import BaseRule
 
@@ -193,4 +194,5 @@ Example Rule
                # Report an error if this table was not SCREAMING_CASE
                ctx.report(
                    self.TableNotLoudEnough(name=table_name),
-                   node=node.relation)
+                   node=node.relation,
+                   severity=Severity.HIGH)

squabble/lint.py

@@ -1,12 +1,13 @@
 """ linting engine """
 
 import collections
+import enum
 
 import pglast
 
 from squabble.rules import Registry
 
-_LintIssue = collections.namedtuple('LintIssue', [
+_LintIssue = collections.namedtuple('_LintIssue', [
     'message',
     'message_text',
     'node',
@@ -23,6 +24,21 @@ class LintIssue(_LintIssue):
     pass
 
 
+class Severity(enum.Enum):
+    """
+    Enumeration describing the relative severity of a :class:`~LintIssue`.
+
+    By themselves, these values don't mean much, but are meant to
+    convey the likely hood that a detected issue is truly
+    problematic. For example, a syntax error in a migration would be
+    ``CRITICAL``, but perhaps a naming inconsistency would be ``LOW``.
+    """
+    LOW = 'LOW'
+    MEDIUM = 'MEDIUM'
+    HIGH = 'HIGH'
+    CRITICAL = 'CRITICAL'
+
+
 def _parse_string(text):
     """Use ``pglast`` to turn ``text`` into a SQL AST."""
     return pglast.Node(pglast.parse_sql(text))
@@ -69,6 +85,10 @@ def report_issue(self, issue):
         self._issues.append(i)
 
     def lint(self):
+        """
+        Run the linter on SQL given in constructor, returning a list of
+        :class:`~LintIssue` discovered.
+        """
         root_ctx = Context(self)
 
         for rule, config in self._rules:
@@ -80,7 +100,7 @@ def lint(self):
 
         except pglast.parser.ParseError as exc:
             root_ctx.report_issue(LintIssue(
-                severity='ERROR',
+                severity=Severity.CRITICAL,
                 message_text=exc.args[0],
                 location=exc.location
             ))
@@ -170,7 +190,7 @@ def report(self, message, node=None, severity=None):
         self.report_issue(LintIssue(
             message=message,
             node=node,
-            severity=severity or 'ERROR',
+            severity=severity or Severity.MEDIUM,
             # This is filled in later
             file=None,
         ))

squabble/reporter.py

@@ -8,6 +8,7 @@
 from colorama import Fore, Style
 
 import squabble
+from squabble.lint import Severity
 
 _REPORTERS = {}
 
@@ -126,21 +127,22 @@ def _issue_info(issue, file_contents):
     formatted = _format_message(issue)
 
     return {
+        **issue._asdict(),
+        **(issue.message.asdict() if issue.message else {}),
         'line_text': line,
         'line': line_num,
         'column': column,
         'message_formatted': formatted,
-        **issue._asdict(),
-        **(issue.message.asdict() if issue.message else {})
+        'severity': issue.severity.name,
     }
 
 
 _SIMPLE_FORMAT = '{file}:{line}:{column} {severity}: {message_formatted}'
 
 # Partially pre-format the message since the color codes will be static.
 _COLOR_FORMAT = '{bold}{{file}}:{reset}{{line}}:{{column}}{reset} '\
-    '{red}{{severity}}{reset}: {{message_formatted}}'\
-    .format(bold=Style.BRIGHT, red=Fore.RED, reset=Style.RESET_ALL)
+    '{{severity}} {{message_formatted}}'\
+    .format(bold=Style.BRIGHT, reset=Style.RESET_ALL)
 
 
 @reporter("plain")
@@ -152,13 +154,26 @@ def plain_text_reporter(issue, file_contents):
     ]
 
 
+_SEVERITY_COLOR = {
+    Severity.CRITICAL: Fore.RED,
+    Severity.HIGH: Fore.RED,
+    Severity.MEDIUM: Fore.YELLOW,
+    Severity.LOW: Fore.BLUE,
+}
+
+
 @reporter('color')
 def color_reporter(issue, file_contents):
     """
     Extension of :func:`squabble.reporter.plain_text_reporter`, uses
     ANSI color and shows error location.
     """
     info = _issue_info(issue, file_contents)
+    info['severity'] = '{color}{severity}{reset}'.format(
+        color=_SEVERITY_COLOR[issue.severity],
+        severity=issue.severity.name,
+        reset=Style.RESET_ALL
+    )
 
     output = [_COLOR_FORMAT.format(**info)]