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| 1 | +/* |
| 2 | + * Copyright 2026 Code Intelligence GmbH |
| 3 | + * |
| 4 | + * Licensed under the Apache License, Version 2.0 (the "License"); |
| 5 | + * you may not use this file except in compliance with the License. |
| 6 | + * You may obtain a copy of the License at |
| 7 | + * |
| 8 | + * http://www.apache.org/licenses/LICENSE-2.0 |
| 9 | + * |
| 10 | + * Unless required by applicable law or agreed to in writing, software |
| 11 | + * distributed under the License is distributed on an "AS IS" BASIS, |
| 12 | + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 13 | + * See the License for the specific language governing permissions and |
| 14 | + * limitations under the License. |
| 15 | + */ |
| 16 | + |
| 17 | +import { PluginItem, transformSync } from "@babel/core"; |
| 18 | + |
| 19 | +import { compareHooks } from "./plugins/compareHooks"; |
| 20 | +import { esmCodeCoverage } from "./plugins/esmCodeCoverage"; |
| 21 | +import { SourceMap, SourceMapRegistry } from "./SourceMapRegistry"; |
| 22 | + |
| 23 | +const COUNTER_ARRAY = "__jazzer_cov"; |
| 24 | + |
| 25 | +/** |
| 26 | + * Replicate the ESM loader's instrumentModule logic so we can test |
| 27 | + * the source map handling without running a real loader thread. |
| 28 | + */ |
| 29 | +function instrumentModule( |
| 30 | + code: string, |
| 31 | + filename: string, |
| 32 | + extraPlugins: PluginItem[] = [], |
| 33 | +): { source: string; map: SourceMap | null } | null { |
| 34 | + const fuzzerCoverage = esmCodeCoverage(); |
| 35 | + const plugins: PluginItem[] = [ |
| 36 | + fuzzerCoverage.plugin, |
| 37 | + compareHooks, |
| 38 | + ...extraPlugins, |
| 39 | + ]; |
| 40 | + |
| 41 | + const transformed = transformSync(code, { |
| 42 | + filename, |
| 43 | + sourceFileName: filename, |
| 44 | + sourceMaps: true, |
| 45 | + plugins, |
| 46 | + sourceType: "module", |
| 47 | + }); |
| 48 | + |
| 49 | + const edges = fuzzerCoverage.edgeCount(); |
| 50 | + if (edges === 0 || !transformed?.code) { |
| 51 | + return null; |
| 52 | + } |
| 53 | + |
| 54 | + const preambleLines = [ |
| 55 | + `const ${COUNTER_ARRAY} = Fuzzer.coverageTracker.createModuleCounters(${edges});`, |
| 56 | + ]; |
| 57 | + |
| 58 | + let shiftedMap: SourceMap | null = null; |
| 59 | + if (transformed.map) { |
| 60 | + const preambleOffset = preambleLines.length + 1; |
| 61 | + shiftedMap = { |
| 62 | + ...transformed.map, |
| 63 | + mappings: ";".repeat(preambleOffset) + transformed.map.mappings, |
| 64 | + } as SourceMap; |
| 65 | + preambleLines.push( |
| 66 | + `__jazzer_registerSourceMap(${JSON.stringify(filename)}, ${JSON.stringify(shiftedMap)});`, |
| 67 | + ); |
| 68 | + } |
| 69 | + |
| 70 | + return { |
| 71 | + source: preambleLines.join("\n") + "\n" + transformed.code, |
| 72 | + map: shiftedMap, |
| 73 | + }; |
| 74 | +} |
| 75 | + |
| 76 | +describe("ESM source map handling", () => { |
| 77 | + it("should produce a separate source map, not an inline one", () => { |
| 78 | + const result = instrumentModule( |
| 79 | + "export function greet() { return 'hi'; }", |
| 80 | + "/app/greet.mjs", |
| 81 | + ); |
| 82 | + |
| 83 | + expect(result).not.toBeNull(); |
| 84 | + expect(result!.source).not.toContain("sourceMappingURL=data:"); |
| 85 | + expect(result!.map).not.toBeNull(); |
| 86 | + expect(result!.map!.version).toBe(3); |
| 87 | + }); |
| 88 | + |
| 89 | + it("should shift mappings by the number of preamble lines", () => { |
| 90 | + const result = instrumentModule( |
| 91 | + "export function greet() { return 'hi'; }", |
| 92 | + "/app/greet.mjs", |
| 93 | + ); |
| 94 | + |
| 95 | + expect(result!.map).not.toBeNull(); |
| 96 | + const mappings = result!.map!.mappings; |
| 97 | + |
| 98 | + // The preamble has 2 lines (counter allocation + source map registration). |
| 99 | + // Each prepended ";" represents an unmapped generated line. |
| 100 | + expect(mappings.startsWith(";;")).toBe(true); |
| 101 | + |
| 102 | + // The real mappings follow — they should not be empty. |
| 103 | + const realMappings = mappings.replace(/^;+/, ""); |
| 104 | + expect(realMappings.length).toBeGreaterThan(0); |
| 105 | + }); |
| 106 | + |
| 107 | + it("should embed a registration call in the preamble", () => { |
| 108 | + const filename = "/app/target.mjs"; |
| 109 | + const result = instrumentModule( |
| 110 | + "export function check(s) { if (s === 'x') throw new Error(); }", |
| 111 | + filename, |
| 112 | + ); |
| 113 | + |
| 114 | + const lines = result!.source.split("\n"); |
| 115 | + |
| 116 | + // Line 1: counter allocation |
| 117 | + expect(lines[0]).toContain("Fuzzer.coverageTracker.createModuleCounters"); |
| 118 | + |
| 119 | + // Line 2: source map registration with the correct filename |
| 120 | + expect(lines[1]).toContain("__jazzer_registerSourceMap"); |
| 121 | + expect(lines[1]).toContain(JSON.stringify(filename)); |
| 122 | + |
| 123 | + // The registration call should contain valid JSON for the source map |
| 124 | + const match = lines[1].match(/__jazzer_registerSourceMap\([^,]+, (.+)\);$/); |
| 125 | + expect(match).not.toBeNull(); |
| 126 | + const embeddedMap = JSON.parse(match![1]); |
| 127 | + expect(embeddedMap.version).toBe(3); |
| 128 | + expect(embeddedMap.sources).toContain(filename); |
| 129 | + }); |
| 130 | + |
| 131 | + it("should register maps with SourceMapRegistry via the global", () => { |
| 132 | + const registry = new SourceMapRegistry(); |
| 133 | + const filename = "/app/module.mjs"; |
| 134 | + const fakeMap: SourceMap = { |
| 135 | + version: 3, |
| 136 | + sources: [filename], |
| 137 | + names: [], |
| 138 | + mappings: "AAAA", |
| 139 | + file: filename, |
| 140 | + }; |
| 141 | + |
| 142 | + // Simulate what Instrumentor.init() installs |
| 143 | + (globalThis as Record<string, unknown>).__jazzer_registerSourceMap = ( |
| 144 | + f: string, |
| 145 | + m: SourceMap, |
| 146 | + ) => registry.registerSourceMap(f, m); |
| 147 | + |
| 148 | + // Simulate what the preamble does at module evaluation time |
| 149 | + const register = (globalThis as Record<string, unknown>) |
| 150 | + .__jazzer_registerSourceMap as (f: string, m: SourceMap) => void; |
| 151 | + register(filename, fakeMap); |
| 152 | + |
| 153 | + expect(registry.getSourceMap(filename)).toEqual(fakeMap); |
| 154 | + |
| 155 | + // Cleanup |
| 156 | + delete (globalThis as Record<string, unknown>).__jazzer_registerSourceMap; |
| 157 | + }); |
| 158 | + |
| 159 | + it("should preserve original source file in the map", () => { |
| 160 | + const filename = "/project/src/lib.mjs"; |
| 161 | + const result = instrumentModule( |
| 162 | + [ |
| 163 | + "export function add(a, b) {", |
| 164 | + " return a + b;", |
| 165 | + "}", |
| 166 | + "export function sub(a, b) {", |
| 167 | + " return a - b;", |
| 168 | + "}", |
| 169 | + ].join("\n"), |
| 170 | + filename, |
| 171 | + ); |
| 172 | + |
| 173 | + expect(result!.map!.sources).toContain(filename); |
| 174 | + expect(result!.map!.mappings.split(";").length).toBeGreaterThan(2); |
| 175 | + }); |
| 176 | +}); |
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