feat(go): run go fmt and go build after code generation

To ensure the generated go code is formatted and compiles by executing `go fmt`
and `go build` on the output directory.

In order to be able to do that within mono-repos (and in the jsii repo itself), we need to be able to resolve local dependencies (same as all other languages).

Resolves #2463

packages/jsii-pacmak/lib/targets/go.ts

@@ -5,19 +5,29 @@ import { Rosetta } from 'jsii-rosetta';
 import * as path from 'path';
 
 import { IGenerator } from '../generator';
+import * as logging from '../logging';
 import { Target, TargetOptions } from '../target';
+import { shell } from '../util';
 import { Documentation } from './go/documentation';
-import { RootPackage } from './go/package';
+import { GOMOD_FILENAME, RootPackage } from './go/package';
 import { JSII_INIT_PACKAGE } from './go/runtime';
+import { JSII_RT_MODULE_NAME } from './go/runtime/constants';
 import { goPackageName } from './go/util';
 
 export class Golang extends Target {
-  public readonly generator: IGenerator;
+  private readonly goGenerator: GoGenerator;
+
+  private readonly goPackageName: string;
 
   public constructor(options: TargetOptions) {
     super(options);
 
-    this.generator = new GoGenerator(options.rosetta);
+    this.goPackageName = goPackageName(this.assembly.name);
+    this.goGenerator = new GoGenerator(options.rosetta);
+  }
+
+  public get generator(): IGenerator {
+    return this.goGenerator;
   }
 
   /**
@@ -27,7 +37,78 @@ export class Golang extends Target {
    * @param outDir    the directory where the publishable artifact should be placed.
    */
   public async build(sourceDir: string, outDir: string): Promise<void> {
-    return this.copyFiles(sourceDir, outDir);
+    await this.copyFiles(sourceDir, outDir);
+
+    // resolve symlinks
+    outDir = await fs.realpath(outDir);
+
+    // append a "replace" directive for local dependencies
+    await this.replaceLocalDeps(outDir);
+
+    // run `go fmt` and `go build` in outdir to format and compile
+    const pkgout = path.resolve(outDir, this.goPackageName);
+    await shell('go', ['fmt'], { cwd: pkgout });
+    await shell('go', ['build'], { cwd: pkgout });
+  }
+
+  /**
+   * Appends a `replace` directive in the generated `go.mod` for local
+   * dependencies.
+   * @param outDir The dist output directory (e.g. `<packageRoot>/dist/go`).
+   */
+  private async replaceLocalDeps(outDir: string) {
+    const rootPackage = this.goGenerator.rootPackage;
+    if (!rootPackage) {
+      throw new Error(`assertion failed: "rootPackage" is undefined`);
+    }
+
+    // find local deps by check if `<jsii.outdir>/go` exists for dependencies
+    // and also consider _out_ output directory in case pacmak is executed using
+    // `--outdir` (in which case all go code will be generated there).
+    const localDeps = [
+      outDir,
+      ...(await this.findLocalDepsOutput(this.packageDir)),
+    ];
+
+    const replace: { [from: string]: string } = {};
+
+    // try to resolve @jsii/go-runtime (only exists as a devDependency)
+    const localRuntime = tryFindLocalRuntime();
+    if (localRuntime) {
+      replace[JSII_RT_MODULE_NAME] = localRuntime;
+    }
+
+    // iterate over all local directories and try to match them with one this
+    // module's deps.
+    for (const localDep of localDeps) {
+      for (const dep of rootPackage.packageDependencies) {
+        const localpath = path.join(localDep, goPackageName(dep.packageName));
+        if (fs.existsSync(localpath)) {
+          replace[dep.goModuleName] = localpath;
+        }
+      }
+    }
+
+    // emit "replace" directive (if relevant)
+    if (Object.keys(replace).length > 0) {
+      const pkgOut = path.join(outDir, this.goPackageName);
+      const lines = new Array<string>();
+
+      lines.push('replace (');
+
+      for (const [from, to] of Object.entries(replace)) {
+        const rel = path.relative(pkgOut, to);
+        logging.debug(`Local dependency: ${from} => ${rel} (${to})`);
+        lines.push(`\t${from} => ${rel}`);
+      }
+
+      lines.push(')');
+
+      await fs.appendFile(
+        path.join(pkgOut, GOMOD_FILENAME),
+        `\n${lines.join('\n')}`,
+      );
+    }
   }
 }
 
@@ -39,6 +120,8 @@ class GoGenerator implements IGenerator {
   });
   private readonly documenter: Documentation;
 
+  public rootPackage: RootPackage | undefined;
+
   public constructor(private readonly rosetta: Rosetta) {
     this.documenter = new Documentation(this.code, this.rosetta);
   }
@@ -53,7 +136,9 @@ class GoGenerator implements IGenerator {
   }
 
   public generate(): void {
-    new RootPackage(this.assembly).emit({
+    this.rootPackage = new RootPackage(this.assembly);
+
+    return this.rootPackage.emit({
       code: this.code,
       documenter: this.documenter,
     });
@@ -94,3 +179,18 @@ class GoGenerator implements IGenerator {
     this.code.closeFile(file);
   }
 }
+
+/**
+ * Check if we are running from inside the jsii repository, and then we want to
+ * use the local runtime instead of download from a released version.
+ */
+function tryFindLocalRuntime() {
+  try {
+    const p = require.resolve('@jsii/go-runtime/jsii-experimental/go.mod');
+    const dir = path.dirname(p);
+    logging.debug(`Using @jsii/go-runtime from ${dir}`);
+    return dir;
+  } catch {
+    return undefined;
+  }
+}

packages/jsii-pacmak/package.json

@@ -53,6 +53,7 @@
   "devDependencies": {
     "@jsii/dotnet-runtime": "^0.0.0",
     "@jsii/java-runtime": "^0.0.0",
+    "@jsii/go-runtime": "^0.0.0",
     "@scope/jsii-calc-lib": "^0.0.0",
     "@types/clone": "^2.1.0",
     "@types/commonmark": "^0.27.4",

packages/jsii-pacmak/test/generated-code/harness.ts

@@ -96,7 +96,9 @@ export function checkTree(
       expect({ [TARBALL]: relativeFile }).toMatchSnapshot(snapshotName);
     } else {
       expect({
-        [FILE]: fs.readFileSync(file, { encoding: 'utf-8' }),
+        [FILE]: normalizeLocalReferences(
+          fs.readFileSync(file, { encoding: 'utf-8' }),
+        ),
       }).toMatchSnapshot(snapshotName);
     }
     return path.basename(file);
@@ -232,3 +234,15 @@ function formatTree(tree: TreeStructure): string {
     })
     .join('\n');
 }
+
+/**
+ * Replaces any string that represents the absolute path of the
+ * jsii root directory with `<jsiiRoot>` to maintain deterministic
+ * output across environments.
+ */
+function normalizeLocalReferences(s: string) {
+  return s.replace(
+    path.resolve(__dirname, '..', '..', '..', '..'),
+    '<jsiiRoot>',
+  );
+}