fix: map functions without closing brace mapping

package.json

@@ -77,6 +77,9 @@
   "pnpm": {
     "overrides": {
       "@vitest/coverage-v8>ast-v8-to-istanbul": "./"
+    },
+    "patchedDependencies": {
+      "istanbul-lib-source-maps": "patches/istanbul-lib-source-maps.patch"
     }
   },
   "prettier": {}

patches/istanbul-lib-source-maps.patch

@@ -0,0 +1,36 @@
+diff --git a/CHANGELOG.md b/CHANGELOG.md
+deleted file mode 100644
+index dad8c06aac26cb8cfced31da5f35ac8e95915f15..0000000000000000000000000000000000000000
+diff --git a/lib/get-mapping.js b/lib/get-mapping.js
+index 187a02ed65104d8e3a058d6bfe7dc8bd7c285369..10dbf17549a6a0795e868bbc2ea6d0df661da514 100644
+--- a/lib/get-mapping.js
++++ b/lib/get-mapping.js
+@@ -36,13 +36,26 @@ function originalEndPositionFor(sourceMap, generatedEnd) {
+     // generated file end location. Note however that this position on its
+     // own is not useful because it is the position of the _start_ of the range
+     // on the original file, and we want the _end_ of the range.
+-    const beforeEndMapping = originalPositionTryBoth(
++    let beforeEndMapping = originalPositionTryBoth(
+         sourceMap,
+         generatedEnd.line,
+         generatedEnd.column - 1
+     );
+     if (beforeEndMapping.source === null) {
+-        return null;
++        for (
++            let line = generatedEnd.line;
++            line > 0 && beforeEndMapping.source === null;
++            line--
++        ) {
++            beforeEndMapping = originalPositionTryBoth(
++                sourceMap,
++                line,
++                Number.MAX_SAFE_INTEGER
++            );
++        }
++        if (beforeEndMapping.source === null) {
++            return null;
++        }
+     }
+
+     // Convert that original position back to a generated one, with a bump

src/location.ts

@@ -91,15 +91,18 @@ export class Locator {
 
     let end = getPosition(endNeedle, this.#map);
 
-    // e.g. tsc that doesnt include } in source maps
-    if (end === null) {
-      endNeedle.column++;
-      end = getPosition(endNeedle, this.#map);
-    }
-
     if (end === null) {
+      // search the previous lines as the mapping was not found on the same line
+      // e.g. tsc that doesnt include } in source maps
+      for (
+        let line = endNeedle.line;
+        line >= startNeedle.line && end === null;
+        line--
+      ) {
+        end = getPosition({ line, column: Infinity }, this.#map);
+      }
       // Does not exist in source maps, e.g. generated code
-      return null;
+      if (end === null) return null;
     }
 
     const loc = { start, end };

test/location.test.ts

@@ -102,3 +102,39 @@ function sum(a, b) {
   expect(locator.offsetToNeedle(start)).toEqual({ line: 2, column: 9 });
   expect(locator.offsetToNeedle(end)).toEqual({ line: 2, column: 12 });
 });
+
+test("getLoc returns mapped location for positions without end mapping", () => {
+  const code = `\
+export function isEven(a: number) {
+  return a % 2 === 0
+}
+
+export function isOdd(a: number) {
+  return !isEven(a)
+}
+`;
+  const map = {
+    version: 3 as const,
+    mappings:
+      "AAAA,OAAO,SAAS,OAAO,GAAW;AAChC,QAAO,IAAI,MAAM;;AAGnB,OAAO,SAAS,MAAM,GAAW;AAC/B,QAAO,CAAC,OAAO,EAAE",
+    sources: ["even.ts"],
+    names: [],
+  };
+
+  const locator = new Locator(code, new TraceMap(map), "");
+
+  expect(locator.getLoc({ start: 25, end: 50 })).toEqual({
+    start: {
+      filename: "even.ts",
+      line: 1,
+      column: 23,
+    },
+    end: {
+      source: "even.ts",
+      filename: "even.ts",
+      line: 2,
+      column: 19,
+      name: null,
+    },
+  });
+});

test/svelte.test.ts

@@ -19,9 +19,9 @@ test("svelte for loop", async ({ actual, expected }) => {
   expect(actual).toMatchInlineSnapshot(`
     {
       "branches": "0/0 (100%)",
-      "functions": "0/3 (0%)",
+      "functions": "0/4 (0%)",
       "lines": "0/3 (0%)",
-      "statements": "0/5 (0%)",
+      "statements": "0/6 (0%)",
     }
   `);
 

test/vue.test.ts

@@ -19,9 +19,9 @@ test("vue for loop", async ({ actual, expected }) => {
   expect(actual).toMatchInlineSnapshot(`
     {
       "branches": "0/0 (100%)",
-      "functions": "0/0 (100%)",
-      "lines": "0/2 (0%)",
-      "statements": "0/2 (0%)",
+      "functions": "0/1 (0%)",
+      "lines": "0/3 (0%)",
+      "statements": "0/3 (0%)",
     }
   `);