Update LcovParser field value parsing (#141)

Fixed the parsing of field values that contain colons.

This unfortunate bug removed everything up to the last colon in the
field value.
With these changes, the bug mentioned in #140 is fixed.

Author: friedemannsommer

.changeset/old-kiwis-wait.md

@@ -0,0 +1,5 @@
+---
+"@friedemannsommer/lcov-parser": patch
+---
+
+Fixed a bug which stripped everything up to the last colon, when parsing field values that contain colons.

src/parser.ts

@@ -177,7 +177,11 @@ export class LcovParser {
                     continue
                 }
 
-                const result = nonEmptyField ? LcovParser._parseValue(buf, byteIndex + 1, isComment) : null
+                // if the current field is a comment, offset the current index by one
+                // (so that it points to the value just after the field token).
+                // for any other non-empty field, we've already checked that the next value is a colon,
+                // so we can offset the index by two.
+                const result = nonEmptyField ? LcovParser._parseValue(buf, byteIndex + (isComment ? 1 : 2)) : null
                 let value = null
 
                 if (result !== null) {
@@ -219,19 +223,16 @@ export class LcovParser {
     /**
      * @internal
      */
-    private static _parseValue(buf: Buffer, offset: number, startAtOffset: boolean): ParseValueResult | null {
+    private static _parseValue(buf: Buffer, offset: number): ParseValueResult | null {
         const length = buf.byteLength
-        let start = offset
 
         for (let index = offset; index < length; index++) {
             const byte = buf[index]
 
-            if (!startAtOffset && byte === 58 /* ':' (colon) */) {
-                start = index + 1
-            } else if (byte === 10 /* '\n' (new line) */) {
+            if (byte === 10 /* '\n' (new line) */) {
                 return {
                     lastIndex: index,
-                    value: LcovParser._parseSlice(buf, start, index)
+                    value: LcovParser._parseSlice(buf, offset, index)
                 }
             }
         }

src/tests/parser.spec.ts

@@ -225,3 +225,32 @@ describe('LcovParser - empty fields', (): void => {
         expect(parser.read()).to.eql(getParseResult(Variant.None, null, false, true))
     })
 })
+
+describe('LcovParser - Paths containing colons', (): void => {
+    it('should process valid Windows like path', (): void => {
+        const parser = new LcovParser(defaultFieldNames)
+
+        parser.write(
+            Buffer.from(
+                getRawLcov(
+                    defaultFieldNames.filePath,
+                    'C:\\Users\\Example\\Documents\\Projects\\example\\src\\example.file'
+                )
+            )
+        )
+
+        expect(parser.read()).to.eql(
+            getParseResult(Variant.FilePath, ['C:\\Users\\Example\\Documents\\Projects\\example\\src\\example.file'])
+        )
+        expect(parser.read()).to.eql(getParseResult(Variant.None, null, true))
+    })
+
+    it('should process a path containing multiple colons', (): void => {
+        const parser = new LcovParser(defaultFieldNames)
+
+        parser.write(Buffer.from(getRawLcov(defaultFieldNames.filePath, '/this/is/a/path:with:colons')))
+
+        expect(parser.read()).to.eql(getParseResult(Variant.FilePath, ['/this/is/a/path:with:colons']))
+        expect(parser.read()).to.eql(getParseResult(Variant.None, null, true))
+    })
+})