Improve coverage

src/utils/collapseSourcemaps.ts

@@ -58,7 +58,7 @@ class Link {
 			const tracedLine: SourceMapSegment[] = [];
 
 			for (const segment of line) {
-				if (segment.length == 1) continue;
+				if (segment.length === 1) continue;
 				const source = this.sources[segment[1]];
 				if (!source) continue;
 
@@ -130,9 +130,7 @@ class Link {
 			if (segment[0] === column || searchStart === searchEnd) {
 				if (segment.length == 1) return null;
 				const source = this.sources[segment[1]];
-				if (!source) {
-					return null;
-				}
+				if (!source) return null;
 
 				return source.traceSegment(
 					segment[2],

src/utils/getOriginalLocation.ts

@@ -2,24 +2,24 @@ import type { DecodedSourceMapOrMissing, ExistingDecodedSourceMap } from '../rol
 
 export function getOriginalLocation(
 	sourcemapChain: readonly DecodedSourceMapOrMissing[],
-	location: { column: number; line: number; name?: string; source?: string }
+	location: { column: number; line: number }
 ): { column: number; line: number } {
 	const filteredSourcemapChain = sourcemapChain.filter(
 		(sourcemap): sourcemap is ExistingDecodedSourceMap => !!sourcemap.mappings
 	);
 	traceSourcemap: while (filteredSourcemapChain.length > 0) {
 		const sourcemap = filteredSourcemapChain.pop()!;
 		const line = sourcemap.mappings[location.line - 1];
-
-		if (line?.length) {
-			for (const segment of line) {
-				if (segment[0] >= location.column || line.length === 1) {
-					if (segment.length === 1) break;
+		if (line) {
+			const filteredLine = line.filter(
+				(segment): segment is [number, number, number, number] => segment.length > 1
+			);
+			const lastSegment = filteredLine[filteredLine.length - 1];
+			for (const segment of filteredLine) {
+				if (segment[0] >= location.column || segment === lastSegment) {
 					location = {
 						column: segment[3],
-						line: segment[2] + 1,
-						name: segment.length === 5 ? sourcemap.names[segment[4]] : undefined,
-						source: sourcemap.sources[segment[1]]
+						line: segment[2] + 1
 					};
 					continue traceSourcemap;
 				}

test/function/samples/cannot-resolve-sourcemap-warning/_config.js

@@ -7,7 +7,7 @@ module.exports = {
 		plugins: {
 			name: 'test-plugin',
 			transform() {
-				return { code: 'export default this', map: { mappings: 'X' } };
+				return { code: 'export default this', map: { mappings: '' } };
 			}
 		}
 	},

test/function/samples/warning-low-resolution-location/_config.js

@@ -11,7 +11,7 @@ module.exports = {
 				// each entry of each line consist of
 				// [generatedColumn, sourceIndex, sourceLine, sourceColumn];
 				// this mapping only maps the first line to itself
-				const decodedMap = [[[0, 0, 0, 0]]];
+				const decodedMap = [[[0], [0, 0, 0, 0], [1]]];
 				return { code: 'export default this', map: { mappings: encode(decodedMap), sources: [] } };
 			}
 		}