init commit

backend/node_modules/istanbul-lib-instrument/src/read-coverage.js

@@ -0,0 +1,77 @@
+const { parseSync, traverse } = require('@babel/core');
+const { defaults } = require('@istanbuljs/schema');
+const { MAGIC_KEY, MAGIC_VALUE } = require('./constants');
+
+function getAst(code) {
+    if (typeof code === 'object' && typeof code.type === 'string') {
+        // Assume code is already a babel ast.
+        return code;
+    }
+
+    if (typeof code !== 'string') {
+        throw new Error('Code must be a string');
+    }
+
+    // Parse as leniently as possible
+    return parseSync(code, {
+        babelrc: false,
+        configFile: false,
+        parserOpts: {
+            allowAwaitOutsideFunction: true,
+            allowImportExportEverywhere: true,
+            allowReturnOutsideFunction: true,
+            allowSuperOutsideMethod: true,
+            sourceType: 'unambiguous',
+            plugins: defaults.instrumenter.parserPlugins
+        }
+    });
+}
+
+module.exports = function readInitialCoverage(code) {
+    const ast = getAst(code);
+
+    let covScope;
+    traverse(ast, {
+        ObjectProperty(path) {
+            const { node } = path;
+            if (
+                !node.computed &&
+                path.get('key').isIdentifier() &&
+                node.key.name === MAGIC_KEY
+            ) {
+                const magicValue = path.get('value').evaluate();
+                if (!magicValue.confident || magicValue.value !== MAGIC_VALUE) {
+                    return;
+                }
+                covScope =
+                    path.scope.getFunctionParent() ||
+                    path.scope.getProgramParent();
+                path.stop();
+            }
+        }
+    });
+
+    if (!covScope) {
+        return null;
+    }
+
+    const result = {};
+
+    for (const key of ['path', 'hash', 'gcv', 'coverageData']) {
+        const binding = covScope.getOwnBinding(key);
+        if (!binding) {
+            return null;
+        }
+        const valuePath = binding.path.get('init');
+        const value = valuePath.evaluate();
+        if (!value.confident) {
+            return null;
+        }
+        result[key] = value.value;
+    }
+
+    delete result.coverageData[MAGIC_KEY];
+    delete result.coverageData.hash;
+
+    return result;
+};