From b65860fee2e842c31cf6e52122561a962617eec0 Mon Sep 17 00:00:00 2001
From: Alan Agius <alan.agius4@gmail.com>
Date: Mon, 17 Sep 2018 14:54:42 +0200
Subject: [PATCH] feat(@ngtools/webpack): add support for `traceResolution`

Closes #8676
---
 packages/ngtools/webpack/src/compiler_host.ts |  4 ++++
 .../e2e/tests/misc/trace-resolution.ts        | 22 +++++++++++++++++++
 2 files changed, 26 insertions(+)
 create mode 100644 tests/legacy-cli/e2e/tests/misc/trace-resolution.ts

diff --git a/packages/ngtools/webpack/src/compiler_host.ts b/packages/ngtools/webpack/src/compiler_host.ts
index a5c2572dfdce..2c0ea9b65c93 100644
--- a/packages/ngtools/webpack/src/compiler_host.ts
+++ b/packages/ngtools/webpack/src/compiler_host.ts
@@ -246,6 +246,10 @@ export class WebpackCompilerHost implements ts.CompilerHost {
       return this.readFile(fileName);
     }
   }
+
+  trace(message: string) {
+    console.log(message);
+  }
 }
 
 
diff --git a/tests/legacy-cli/e2e/tests/misc/trace-resolution.ts b/tests/legacy-cli/e2e/tests/misc/trace-resolution.ts
new file mode 100644
index 000000000000..30c8113ce9ec
--- /dev/null
+++ b/tests/legacy-cli/e2e/tests/misc/trace-resolution.ts
@@ -0,0 +1,22 @@
+import { ng } from '../../utils/process';
+import { updateJsonFile } from '../../utils/project';
+
+export default async function () {
+  await updateJsonFile('tsconfig.json', tsconfig => {
+    tsconfig.compilerOptions.traceResolution = true;
+  });
+
+  const { stdout: stdoutTraced } = await ng('build');
+  if (!/Resolving module/.test(stdoutTraced)) {
+    throw new Error(`Modules resolutions must be printed when 'traceResolution' is enabled.`);
+  }
+
+  await updateJsonFile('tsconfig.json', tsconfig => {
+    tsconfig.compilerOptions.traceResolution = false;
+  });
+
+  const { stdout: stdoutUnTraced } = await ng('build');
+  if (/Resolving module/.test(stdoutUnTraced)) {
+    throw new Error(`Modules resolutions must not be printed when 'traceResolution' is disabled.`);
+  }
+}