Add full file checker CheckInsertFinalNewLineRule.

editorconfig/full_file_checkers.go

@@ -6,7 +6,10 @@ import (
 )
 
 var fullFileCheckers = map[string]FullFileChecker{
-	"end_of_line": CheckEndOfLineRule,
+	"end_of_line":          CheckEndOfLineRule,
+	"insert_final_newline": CheckInsertFinalNewLineRule,
+	// @todo - add checker for charset.
+	// "charset":              CheckCharsetRule,
 }
 
 type FullFileChecker func(ruleValue string, fileContent string) *FullFileCheckResult
@@ -59,3 +62,36 @@ func CheckEndOfLineRule(ruleValue string, fileContent string) *FullFileCheckResu
 
 	return &FullFileCheckResult{isOk: true}
 }
+
+var endsWithFinalNewLineRegexp = regexp.MustCompile(`(\n|\r|\r\n)$`)
+
+func CheckInsertFinalNewLineRule(ruleValue string, fileContent string) *FullFileCheckResult {
+	// Valid rules values are "true" or "false". The values are case insensitive.
+	ruleValueLowercase := strings.ToLower(ruleValue)
+
+	if ruleValueLowercase != "true" && ruleValueLowercase != "false" {
+		return &FullFileCheckResult{isOk: false, messageIfNotOk: "insert_final_new_line value should be true or false, is: " + ruleValue}
+	}
+
+	if len(fileContent) == 0 {
+		return &FullFileCheckResult{isOk: true}
+	}
+
+	if ruleValueLowercase == "true" {
+		if endsWithFinalNewLineRegexp.MatchString(fileContent) {
+			return &FullFileCheckResult{isOk: true}
+		} else {
+			return &FullFileCheckResult{isOk: false, messageIfNotOk: "should end with an empty line but it does not"}
+		}
+	}
+
+	if ruleValueLowercase == "false" {
+		if !endsWithFinalNewLineRegexp.MatchString(fileContent) {
+			return &FullFileCheckResult{isOk: true}
+		} else {
+			return &FullFileCheckResult{isOk: false, messageIfNotOk: "should not end with an empty line but it does"}
+		}
+	}
+
+	return &FullFileCheckResult{isOk: false, messageIfNotOk: "unexpected condition"}
+}

editorconfig/full_file_checkers_test.go

@@ -39,3 +39,31 @@ func TestCheckEndOfLineRule(t *testing.T) {
 	ExpectFileFail("Aardvark\rBunny\r", "crlf", f, t, "should use CRLF for new lines but contains CR")
 	ExpectFileFail("Aardvark\r\nBunny\r\n", "lf", f, t, "should use LF for new lines but contains CRLF")
 }
+
+func TestCheckInsertFinalNewLineRule(t *testing.T) {
+	f := CheckInsertFinalNewLineRule
+
+	// Empty files should never error in this rule.
+	ExpectFilePass("", "true", f, t)
+	ExpectFilePass("", "false", f, t)
+
+	ExpectFilePass("\n", "true", f, t)
+	ExpectFilePass("\r", "true", f, t)
+	ExpectFilePass("a\n", "true", f, t)
+	ExpectFilePass("a\r", "true", f, t)
+	ExpectFilePass("a\r\n", "true", f, t)
+	ExpectFilePass("a\r\n", "true", f, t)
+	ExpectFilePass("a\nb\n", "true", f, t)
+	ExpectFileFail("a", "true", f, t, "should end with an empty line but it does not")
+	ExpectFileFail("a\nb", "true", f, t, "should end with an empty line but it does not")
+	ExpectFileFail("a\rb", "true", f, t, "should end with an empty line but it does not")
+
+	ExpectFilePass("a", "false", f, t)
+	ExpectFilePass("a\nb", "false", f, t)
+	ExpectFileFail("\n", "false", f, t, "should not end with an empty line but it does")
+	ExpectFileFail("\r", "false", f, t, "should not end with an empty line but it does")
+	ExpectFileFail("\r\n", "false", f, t, "should not end with an empty line but it does")
+	ExpectFileFail("a\r\n", "false", f, t, "should not end with an empty line but it does")
+
+	ExpectFileFail("anything", "rabbits", f, t, "insert_final_new_line value should be true or false, is: rabbits")
+}