Add an "api signature" to summaries.

pkg/analyzer/test/src/summary/flat_buffers_test.dart

Index: pkg/analyzer/test/src/summary/flat_buffers_test.dart
diff --git a/pkg/analyzer/test/src/summary/flat_buffers_test.dart b/pkg/analyzer/test/src/summary/flat_buffers_test.dart
index 40b04795e45ab61da90744f844c624fb0ce15fe6..9440d229eef2a806979a39ea001ea9f2fdae8296 100644
--- a/pkg/analyzer/test/src/summary/flat_buffers_test.dart
+++ b/pkg/analyzer/test/src/summary/flat_buffers_test.dart
@@ -7,6 +7,9 @@ library test.src.summary.flat_buffers_test;
 import 'dart:typed_data';
 
 import 'package:analyzer/src/summary/flat_buffers.dart';
+import 'package:analyzer/src/summary/format.dart';
+import 'package:convert/convert.dart';
+import 'package:crypto/crypto.dart';
 import 'package:unittest/unittest.dart';
 
 import '../../reflective_tests.dart';
@@ -14,6 +17,101 @@ import '../../reflective_tests.dart';
 main() {
   groupSep = ' | ';
   runReflectiveTests(BuilderTest);
+  runReflectiveTests(ApiSignatureTest);
+}
+
+@reflectiveTest
+class ApiSignatureTest {
+  ApiSignature sig = new ApiSignature.unversioned();
+
+  void checkBytes(List<int> bytes) {
+    expect(sig.getBytes_forDebug(), bytes);
+    expect(sig.toHex(), hex.encode(md5.convert(bytes).bytes));
+  }
+
+  String signUnlinkedCombinator(UnlinkedCombinatorBuilder combinator) {
+    ApiSignature sig = new ApiSignature();
+    combinator.collectApiSignature(sig);
+    return sig.toHex();
+  }
+
+  void test_addBool() {
+    sig.addBool(true);
+    sig.addBool(true);
+    sig.addBool(false);
+    sig.addBool(true);
+    sig.addBool(false);
+    sig.addBool(false);
+    sig.addBool(true);
+    sig.addBool(false);
+    checkBytes([1, 1, 0, 1, 0, 0, 1, 0]);
+  }
+
+  void test_addBytes() {
+    // Check that offset works correctly by adding bytes in 2 chunks.
+    sig.addBytes([1, 2, 3, 4, 5]);
+    sig.addBytes([0xff, 0xfe, 0xfd, 0xfc, 0xfb]);
+    checkBytes([1, 2, 3, 4, 5, 0xff, 0xfe, 0xfd, 0xfc, 0xfb]);
+  }
+
+  void test_addDouble() {
+    sig.addDouble(1.0 / 3.0);
+    sig.addDouble(-1.0);
+    checkBytes([85, 85, 85, 85, 85, 85, 213, 63, 0, 0, 0, 0, 0, 0, 240, 191]);
+  }
+
+  void test_addInt() {
+    sig.addInt(1);
+    sig.addInt(1000);
+    sig.addInt(1000000);
+    sig.addInt(1000000000);
+    checkBytes(
+        [1, 0, 0, 0, 0xe8, 3, 0, 0, 0x40, 0x42, 0xf, 0, 0, 0xca, 0x9a, 0x3b]);
+  }
+
+  void test_addString() {
+    sig.addString('abc');
+    sig.addString('\u00f8');
+    checkBytes([3, 0, 0, 0, 0x61, 0x62, 0x63, 2, 0, 0, 0, 0xc3, 0xb8]);
+  }
+
+  void test_excludesInformative() {
+    // Verify that API signatures exclude informative data by checking that two
+    // UnlinkedCombinator instances that differ only in their offset result in
+    // the same signature.
+    UnlinkedCombinatorBuilder combinator1 =
+        new UnlinkedCombinatorBuilder(shows: ['foo'], offset: 1);
+    UnlinkedCombinatorBuilder combinator2 =
+        new UnlinkedCombinatorBuilder(shows: ['foo'], offset: 2);
+    expect(signUnlinkedCombinator(combinator1),
+        signUnlinkedCombinator(combinator2));
+  }
+
+  void test_includesSemantic() {
+    // Verify that API signatures include semantic data by checking that two
+    // UnlinkedCombinator instances that differ only in their "shows" lists
+    // result in different signatures.
+    UnlinkedCombinatorBuilder combinator1 =
+        new UnlinkedCombinatorBuilder(shows: ['foo'], offset: 1);
+    UnlinkedCombinatorBuilder combinator2 =
+        new UnlinkedCombinatorBuilder(shows: ['bar'], offset: 1);
+    expect(signUnlinkedCombinator(combinator1),
+        isNot(signUnlinkedCombinator(combinator2)));
+  }
+
+  void test_manyInts() {
+    // This verifies that the logic to extend the internal buffer works
+    // properly.
+    List<int> expectedResult = [];
+    for (int i = 0; i < 100000; i++) {
+      sig.addInt(i);
+      expectedResult.add(i % 0x100);
+      expectedResult.add((i ~/ 0x100) % 0x100);
+      expectedResult.add((i ~/ 0x10000) % 0x100);
+      expectedResult.add((i ~/ 0x1000000) % 0x100);
+    }
+    checkBytes(expectedResult);
+  }
 }
 
 @reflectiveTest