Fix regex to detect empty lines containing only whitespace

Addressed review feedback: The previous regex only detected consecutive
newlines that were immediately adjacent (\n\n\n). It failed to detect
multiple consecutive empty lines when those lines contained only spaces
or tabs (\n   \n   \n).

Updated regex to treat [ \t]*\r?\n (optional whitespace + newline) as
an empty line, rather than just \r?\n. This ensures that lines containing
only whitespace are properly treated as empty when checking for multiple
consecutive empty lines.

Changes:
- Updated regex pattern: (?<=([ \t]*\r?\n)([ \t]*\r?\n))[ \t]*\r?\n
- Added test file EmptyLinesWithWhitespace.cls with spaces on empty lines
- Added specific test case for whitespace-only empty lines
- Updated existing tests to include new violation

Author: aruntyagiTutu

packages/code-analyzer-regex-engine/src/plugin.ts

@@ -72,7 +72,7 @@ function validateEngineName(engineName: string) {
 export function createBaseRegexRules(now: Date): RegexRules {
     return {
         NoTrailingWhitespace: {
-            regex: (/(?<target>((?<=\S.*)[ \t]+(?=\r?\n|$))|((?<=\r?\n\r?\n)\r?\n))/g).toString(),
+            regex: (/(?<target>((?<=\S.*)[ \t]+(?=\r?\n|$))|((?<=([ \t]*\r?\n)([ \t]*\r?\n))[ \t]*\r?\n))/g).toString(),
             file_extensions: ['.cls', '.trigger'], // Currently restricted to apex files only... but we might want to extend where this rule applies in the future
             description: getMessage('TrailingWhitespaceRuleDescription'),
             violation_message: getMessage('TrailingWhitespaceRuleMessage'),

packages/code-analyzer-regex-engine/test/engine.test.ts

@@ -292,6 +292,18 @@ describe('Tests for runRules', () => {
                     endColumn: 1
                 }]
             },
+            {
+                ruleName: "NoTrailingWhitespace",
+                message: getMessage('TrailingWhitespaceRuleMessage'),
+                primaryLocationIndex: 0,
+                codeLocations: [{
+                    file: path.resolve(__dirname, "test-data", "apexClassWhitespace", "4_multipleEmptyLines", "EmptyLinesWithWhitespace.cls"),
+                    startLine: 6,
+                    startColumn: 1,
+                    endLine: 7,
+                    endColumn: 1
+                }]
+            },
 
         ];
 
@@ -330,6 +342,18 @@ describe('Tests for runRules', () => {
                     endLine: 8,
                     endColumn: 1
                 }]
+            },
+            {
+                ruleName: "NoTrailingWhitespace",
+                message: getMessage('TrailingWhitespaceRuleMessage'),
+                primaryLocationIndex: 0,
+                codeLocations: [{
+                    file: path.resolve(__dirname, "test-data", "apexClassWhitespace", "4_multipleEmptyLines", "EmptyLinesWithWhitespace.cls"),
+                    startLine: 6,
+                    startColumn: 1,
+                    endLine: 7,
+                    endColumn: 1
+                }]
             }
         ];
 
@@ -347,6 +371,32 @@ describe('Tests for runRules', () => {
         expect(runResults.violations).toHaveLength(0);
     });
 
+    it("NoTrailingWhitespace rule should flag multiple empty lines that contain only whitespace", async () => {
+        const runOptions: RunOptions = createRunOptions(
+            new Workspace('id', [path.resolve(__dirname, "test-data", "apexClassWhitespace", "4_multipleEmptyLines", "EmptyLinesWithWhitespace.cls")]));
+        const runResults: EngineRunResults = await engine.runRules(["NoTrailingWhitespace"], runOptions);
+
+        const expectedViolations: Violation[] = [
+            {
+                ruleName: "NoTrailingWhitespace",
+                message: getMessage('TrailingWhitespaceRuleMessage'),
+                primaryLocationIndex: 0,
+                codeLocations: [{
+                    file: path.resolve(__dirname, "test-data", "apexClassWhitespace", "4_multipleEmptyLines", "EmptyLinesWithWhitespace.cls"),
+                    startLine: 6,
+                    startColumn: 1,
+                    endLine: 7,
+                    endColumn: 1
+                }]
+            }
+        ];
+
+        expect(runResults.violations).toHaveLength(expectedViolations.length);
+        for (const expectedViolation of expectedViolations) {
+            expect(runResults.violations).toContainEqual(expectedViolation);
+        }
+    });
+
     it("Ensure runRules when called on a directory of Apex classes with getHeapSize in a loop, it properly emits violations", async () => {
         const runOptions: RunOptions = createRunOptions(
             new Workspace('id', [path.resolve(__dirname, "test-data", "apexClassGetLimitsInLoop")]));

packages/code-analyzer-regex-engine/test/test-data/apexClassWhitespace/4_multipleEmptyLines/EmptyLinesWithWhitespace.cls

@@ -0,0 +1,10 @@
+public class EmptyLinesWithWhitespace {
+    public void method1() {
+        System.debug('test1');
+    }
+   
+   
+    public void method2() {
+        System.debug('test2');
+    }
+}