Add source map spec tests

.gitmodules

@@ -0,0 +1,3 @@
+[submodule "test/source-map-tests"]
+	path = test/source-map-tests
+	url = https://github.com/tc39/source-map-tests.git

package.json

@@ -65,8 +65,8 @@
   },
   "license": "BSD-3-Clause",
   "scripts": {
-    "lint": "eslint --fix *.js lib/ test/",
-    "test": "node test/run-tests.js",
+    "lint": "eslint --fix *.js lib/ test/ --ignore-pattern 'test/source-map-tests/**'",
+    "test": "git submodule update --init --recursive; node test/run-tests.js",
     "coverage": "c8 --reporter=text --reporter=html npm test",
     "prettier": "prettier --write .",
     "clean": "rm -rf coverage",

test/test-spec-tests.js

@@ -0,0 +1,208 @@
+/* -*- Mode: js; js-indent-level: 2; -*- */
+/*
+ * Copyright 2024 Mozilla Foundation and contributors
+ * Licensed under the New BSD license. See LICENSE or:
+ * http://opensource.org/licenses/BSD-3-Clause
+ */
+
+const fs = require("fs").promises;
+const SourceMapConsumer =
+  require("../lib/source-map-consumer").SourceMapConsumer;
+
+const sourceMapSpecTests = require("./source-map-tests/source-map-spec-tests.json");
+
+async function readJSON(path) {
+  const file = await fs.open(require.resolve(path));
+  const json = JSON.parse(await file.readFile());
+  file.close();
+  return json;
+}
+
+// Known failures due to intentional implementation choices or due to bugs.
+const skippedTests = [
+  // Versions are explicitly checked a bit loosely.
+  "versionNumericString",
+  // Stricter sources array checking isn't implemented.
+  "sourcesNotStringOrNull",
+  "sourcesAndSourcesContentBothNull",
+  // Stricter names array checking isn't implemented.
+  "namesMissing",
+  "namesNotString",
+  // This check isn't as strict in this library.
+  "invalidMappingNotAString1",
+  // A mapping segment with no fields is technically invalid in the spec.
+  "invalidMappingSegmentWithZeroFields",
+  // These tests fail due to imprecision in the spec about the 32-bit limit.
+  "invalidMappingSegmentWithColumnExceeding32Bits",
+  "invalidMappingSegmentWithOriginalLineExceeding32Bits",
+  "invalidMappingSegmentWithOriginalColumnExceeding32Bits",
+  // A large VLQ that should parse, but currently does not.
+  "validMappingLargeVLQ",
+  // The library currently doesn't check the types of offset lines/columns.
+  "indexMapOffsetLineWrongType",
+  "indexMapOffsetColumnWrongType",
+  // The spec is not totally clear about this case.
+  "indexMapInvalidBaseMappings",
+  // The spec's definition of overlap can be refined
+  "indexMapInvalidOverlap",
+  // The library doesn't support the new ignoreList feature yet.
+  "ignoreListWrongType1",
+  "ignoreListWrongType2",
+  "ignoreListWrongType3",
+  "ignoreListOutOfBounds",
+];
+
+// The source-map library converts null sources to the "null" URL in its
+// sources list, so for equality checking we accept this as null.
+function nullish(nullOrString) {
+  if (nullOrString === "null") {
+    return null;
+  }
+  return nullOrString;
+}
+
+function mapLine(line) {
+  return line + 1;
+}
+
+async function testMappingAction(assert, rawSourceMap, action) {
+  return SourceMapConsumer.with(rawSourceMap, null, consumer => {
+    let mappedPosition = consumer.originalPositionFor({
+      line: mapLine(action.generatedLine),
+      column: action.generatedColumn,
+    });
+
+    assert.equal(
+      mappedPosition.line,
+      mapLine(action.originalLine),
+      `original line didn't match, expected ${mapLine(
+        action.originalLine
+      )} got ${mappedPosition.line}`
+    );
+    assert.equal(
+      mappedPosition.column,
+      action.originalColumn,
+      `original column didn't match, expected ${action.originalColumn} got ${mappedPosition.column}`
+    );
+    assert.equal(
+      nullish(mappedPosition.source),
+      action.originalSource,
+      `original source didn't match, expected ${action.originalSource} got ${mappedPosition.source}`
+    );
+    if (action.mappedName) {
+      assert.equal(
+        mappedPosition.name,
+        action.mappedName,
+        `mapped name didn't match, expected ${action.mappedName} got ${mappedPosition.name}`
+      );
+    }
+
+    // When the source is null, a reverse lookup may not make sense
+    // because there isn't a unique way to look it up.
+    if (action.originalSource !== null) {
+      mappedPosition = consumer.generatedPositionFor({
+        source: action.originalSource,
+        line: mapLine(action.originalLine),
+        column: action.originalColumn,
+      });
+
+      assert.equal(
+        mappedPosition.line,
+        mapLine(action.generatedLine),
+        `generated line didn't match, expected ${mapLine(
+          action.generatedLine
+        )} got ${mappedPosition.line}`
+      );
+      assert.equal(
+        mappedPosition.column,
+        action.generatedColumn,
+        `generated column didn't match, expected ${action.generatedColumn} got ${mappedPosition.column}`
+      );
+    }
+  });
+}
+
+async function testTransitiveMappingAction(assert, rawSourceMap, action) {
+  return SourceMapConsumer.with(rawSourceMap, null, async consumer => {
+    assert.ok(
+      Array.isArray(action.intermediateMaps),
+      "transitive mapping case requires intermediate maps"
+    );
+
+    let mappedPosition = consumer.originalPositionFor({
+      line: mapLine(action.generatedLine),
+      column: action.generatedColumn,
+    });
+
+    for (const intermediateMapPath of action.intermediateMaps) {
+      const intermediateMap = await readJSON(
+        `./source-map-tests/resources/${intermediateMapPath}`
+      );
+      await SourceMapConsumer.with(
+        intermediateMap,
+        null,
+        consumerIntermediate => {
+          mappedPosition = consumerIntermediate.originalPositionFor({
+            line: mappedPosition.line,
+            column: mappedPosition.column,
+          });
+        }
+      );
+    }
+
+    assert.equal(
+      mappedPosition.line,
+      mapLine(action.originalLine),
+      `original line didn't match, expected ${mapLine(
+        action.originalLine
+      )} got ${mappedPosition.line}`
+    );
+    assert.equal(
+      mappedPosition.column,
+      action.originalColumn,
+      `original column didn't match, expected ${action.originalColumn} got ${mappedPosition.column}`
+    );
+    assert.equal(
+      mappedPosition.source,
+      action.originalSource,
+      `original source didn't match, expected ${action.originalSource} got ${mappedPosition.source}`
+    );
+  });
+}
+
+for (const testCase of sourceMapSpecTests.tests) {
+  if (skippedTests.includes(testCase.name)) {
+    continue;
+  }
+  exports[`test from source map spec tests, name: ${testCase.name}`] =
+    async function (assert) {
+      const json = await readJSON(
+        `./source-map-tests/resources/${testCase.sourceMapFile}`
+      );
+      try {
+        const map = await new SourceMapConsumer(json);
+        map.eachMapping(() => {});
+        map.destroy();
+      } catch (exn) {
+        if (testCase.sourceMapIsValid) {
+          assert.fail(
+            "Expected valid source map but failed to load successfully: " +
+              exn.message
+          );
+        }
+        return;
+      }
+      if (!testCase.sourceMapIsValid) {
+        assert.fail("Expected invalid source map but loaded successfully");
+      }
+      if (testCase.testActions) {
+        for (const testAction of testCase.testActions) {
+          if (testAction.actionType == "checkMapping") {
+            await testMappingAction(assert, json, testAction);
+          } else if (testAction.actionType == "checkMappingTransitive") {
+            await testTransitiveMappingAction(assert, json, testAction);
+          }
+        }
+      }
+    };
+}