spec: create new environment

spec.ts

@@ -356,9 +356,12 @@ export function buildpath(specdir: string, bench: SPECBenchData): string {
     return path.join(benchmarkDir, 'build');
 }
 
-export function setenv(specdir: string): void {
-    process.env.SPEC = specdir;
-    process.env.PATH = `${path.join(specdir, 'bin')}${path.delimiter}${process.env.PATH}`;
+export function getEnvironment(specdir: string): NodeJS.ProcessEnv {
+    return {
+        ...process.env,
+        SPEC: specdir,
+        PATH: `${path.join(specdir, 'bin')}${path.delimiter}${process.env.PATH}`,
+    };
 }
 
 export interface SPEC {
@@ -366,7 +369,7 @@ export interface SPEC {
     benchpath: (bench: SPECBenchData) => string;
     exepath: (bench: SPECBenchData) => string;
     buildpath: (bench: SPECBenchData) => string;
-    setenv: () => void;
+    getEnvironment: () => NodeJS.ProcessEnv;
 }
 
 export function mkSPEC(specRoot: string): SPEC {
@@ -377,7 +380,7 @@ export function mkSPEC(specRoot: string): SPEC {
         benchpath: bench => benchpath(specRoot, bench),
         exepath: bench => exepath(specRoot, bench),
         buildpath: bench => buildpath(specRoot, bench),
-        setenv: () => setenv(specRoot),
+        getEnvironment: () => getEnvironment(specRoot),
     };
 }