Update MD009/no-trailing-spaces default configuration to allow 2 spaces for hard break (fixes #114).

doc/Rules.md

@@ -288,19 +288,17 @@ Tags: whitespace
 
 Aliases: no-trailing-spaces
 
-Parameters: br_spaces, list_item_empty_lines (number; default 0, boolean; default false)
+Parameters: br_spaces, list_item_empty_lines (number; default 2, boolean; default false)
 
-This rule is triggered on any lines that end with whitespace. To fix this,
-find the line that is triggered and remove any trailing spaces from the end.
+This rule is triggered on any lines that end with unexpected whitespace. To fix this,
+remove the trailing space from the end of the line.
 
-The `br_spaces` parameter allows an exception to this rule for a specific amount
-of trailing spaces used to insert an explicit line break/br element. For
-example, set `br_spaces` to 2 to allow exactly 2 spaces at the end of a line.
+The `br_spaces` parameter allows an exception to this rule for a specific number
+of trailing spaces, typically used to insert an explicit line break. The default
+value allows 2 spaces to indicate a hard break (\<br> element).
 
-Note: you have to set `br_spaces` to 2 or higher for this exception to take
-effect - you can't insert a br element with just a single trailing space, so
-if you set `br_spaces` to 1, the exception will be disabled, just as if it was
-set to the default of 0.
+Note: You must set `br_spaces` to a value >= 2 for this parameter to take effect.
+Setting `br_spaces` to 1 behaves the same as 0, disallowing any trailing spaces.
 
 Using spaces to indent blank lines inside a list item is usually not necessary,
 but some parsers require it. Set the `list_item_empty_lines` parameter to `true`
@@ -308,7 +306,7 @@ to allow this:
 
 ```markdown
 - list item text
-
+  [2 spaces]
   list item text
 ```
 

lib/md009.js

@@ -11,7 +11,10 @@ module.exports = {
   "description": "Trailing spaces",
   "tags": [ "whitespace" ],
   "function": function MD009(params, onError) {
-    const brSpaces = params.config.br_spaces || 0;
+    let brSpaces = params.config.br_spaces;
+    if (brSpaces === undefined) {
+      brSpaces = 2;
+    }
     const listItemEmptyLines = params.config.list_item_empty_lines;
     const allowListItemEmptyLines =
       (listItemEmptyLines === undefined) ? false : !!listItemEmptyLines;
@@ -23,14 +26,19 @@ module.exports = {
         }
       });
     }
+    const expected = (brSpaces < 2) ? 0 : brSpaces;
     shared.forEachLine(function forLine(line, lineIndex) {
       const lineNumber = lineIndex + 1;
       if (trailingSpaceRe.test(line) &&
         (listItemLineNumbers.indexOf(lineNumber) === -1)) {
-        const expected = (brSpaces < 2) ? 0 : brSpaces;
-        shared.addErrorDetailIf(onError, lineNumber,
-          expected, line.length - shared.trimRight(line).length, null,
-          shared.rangeFromRegExp(line, trailingSpaceRe));
+        const actual = line.length - shared.trimRight(line).length;
+        if (expected !== actual) {
+          shared.addError(onError, lineNumber,
+            "Expected: " + (expected === 0 ? "" : "0 or ") +
+              expected + "; Actual: " + actual,
+            null,
+            shared.rangeFromRegExp(line, trailingSpaceRe));
+        }
       }
     });
   }

schema/build-config-schema.js

@@ -95,7 +95,7 @@ rules.forEach(function forRule(rule) {
         "br_spaces": {
           "description": "Spaces for line break",
           "type": "integer",
-          "default": 0
+          "default": 2
         },
         "list_item_empty_lines": {
           "description": "Allow spaces for empty lines in list items",

schema/markdownlint-config-schema.json

@@ -256,7 +256,7 @@
         "br_spaces": {
           "description": "Spaces for line break",
           "type": "integer",
-          "default": 0
+          "default": 2
         },
         "list_item_empty_lines": {
           "description": "Allow spaces for empty lines in list items",
@@ -277,7 +277,7 @@
         "br_spaces": {
           "description": "Spaces for line break",
           "type": "integer",
-          "default": 0
+          "default": 2
         },
         "list_item_empty_lines": {
           "description": "Allow spaces for empty lines in list items",

test/detailed-results-MD001-MD010.results.json

@@ -59,7 +59,7 @@
         "lineNumber": 15,
         "ruleNames": [ "MD009", "no-trailing-spaces" ],
         "ruleDescription": "Trailing spaces",
-        "errorDetail": "Expected: 0; Actual: 1",
+        "errorDetail": "Expected: 0 or 2; Actual: 1",
         "errorContext": null,
         "errorRange": [5, 1]
     },

test/detailed-results-front-matter.json

@@ -1,4 +1,7 @@
 {
   "default": true,
+  "MD009": {
+    "br_spaces": 0
+  },
   "MD041": true
 }

test/trailing_spaces_br.json

@@ -1,6 +0,0 @@
-{
-  "default": true,
-  "MD009": {
-    "br_spaces": 2
-  }
-}