Make tool/build.dart verification a “real” test

Author: kevmoo

dart_test.yaml

@@ -0,0 +1,3 @@
+tags:
+  presubmit-only:
+    skip: "Should only be run during presubmit"

test/ensure_build_test.dart

@@ -0,0 +1,57 @@
+@Tags(const ['presubmit-only'])
+
+import 'dart:convert';
+import 'dart:io';
+
+import 'package:test/test.dart';
+
+void main() {
+  String pkgRoot;
+  try {
+    pkgRoot = _runProc('git', ['rev-parse', '--show-toplevel']);
+    var currentDir = Directory.current.resolveSymbolicLinksSync();
+    if (pkgRoot != currentDir) {
+      throw "Expected the git root ($pkgRoot) "
+          "to match the current directory ($currentDir).";
+    }
+  } catch (e) {
+    print("Skipping this test – git didn't run correctly");
+    print(e);
+    return;
+  }
+
+  test("ensure local build succeeds with no changes", () {
+    // 1 - get a list of modified `.g.dart` files - should be empty
+    //expect(_changedGeneratedFiles(), isEmpty);
+
+    // 2 - run build - should be no output, since nothing should change
+    var result = _runProc('dart', ['--checked', 'tool/build.dart']);
+    expect(result,
+        contains(new RegExp(r"Build: Succeeded after \S+ with \d+ outputs")));
+
+    // 3 - get a list of modified `.g.dart` files - should still be empty
+    expect(_changedGeneratedFiles(), isEmpty);
+  });
+}
+
+final _whitespace = new RegExp(r'\s');
+
+Set<String> _changedGeneratedFiles() {
+  var output = _runProc('git', ['status', '--porcelain']);
+
+  return LineSplitter
+      .split(output)
+      .map((line) => line.split(_whitespace).last)
+      .where((path) => path.endsWith('.g.dart'))
+      .toSet();
+}
+
+String _runProc(String proc, List<String> args) {
+  var result = Process.runSync(proc, args);
+
+  if (result.exitCode != 0) {
+    throw new ProcessException(proc, args, result.stderr, result.exitCode);
+  }
+
+  return (result.stdout as String).trim();
+}

tool/travis.sh

@@ -6,11 +6,8 @@ set -e
 # Skipping this until at least we have a dev release that aligns with dart_style version
 # $(dirname -- "$0")/ensure_dartfmt.sh
 
-# Run the tests.
-pub run test
-
-# Run the build.dart file - just to make sure it works
-dart --checked tool/build.dart
+# Run the tests -- include the default-skipped presubmit tests
+pub run test --run-skipped
 
 # Install dart_coveralls; gather and send coverage data.
 if [ "$COVERALLS_TOKEN" ] && [ "$TRAVIS_DART_VERSION" = "stable" ]; then