feature: tag tests; choose tags on command line

test/backend/metadata_test.dart

Index: test/backend/metadata_test.dart
diff --git a/test/backend/metadata_test.dart b/test/backend/metadata_test.dart
index ab14a74bde550a52a9b895f5b73e4085b75c0a37..799fac228f5c83756f840af1d440edaf1efccf34 100644
--- a/test/backend/metadata_test.dart
+++ b/test/backend/metadata_test.dart
@@ -9,6 +9,106 @@ import 'package:test/src/frontend/skip.dart';
 import 'package:test/test.dart';
 
 void main() {
+  group("Metadata", () {
+    void expectTags(tags, expected) {
+      expect(new Metadata.parse(tags: tags).tags, unorderedEquals(expected));
+
+      if (tags == null || tags is Iterable) {
+        expect(new Metadata(tags: tags).tags, unorderedEquals(expected));
+      }
+
+      if (tags is Iterable) {
+        var serialized = {
+          "tags": tags,
+          "timeout": "none",
+          "onPlatform": [],
+        };
+        expect(new Metadata.deserialize(serialized).tags,
+            unorderedEquals(expected));

[nweiz, 2015/11/16 21:59:44]

I don't think we should explicitly test the serialized representation. At most,
we should test that deserialize can consume a serialized representation of a few
representative tag lists.

[yjbanov, 2015/11/26 06:30:27]

Done.

+      }
+    }
+
+    void expectArgumentError(ArgumentError error, tags, String message) {

[nweiz, 2015/11/16 21:59:44]

We usually don't test argument errors' values in this level of depth. Just
throwsArgumentError should be sufficient.

[yjbanov, 2015/11/26 06:30:27]

Done.

+      expect(error.message, message);
+      expect(error.invalidValue, tags);
+      expect(error.name, "tags");
+    }
+
+    void expectTagsError({tags, String message}) {
+      [
+        () => new Metadata(tags: tags),
+        () => new Metadata.parse(tags: tags),
+      ].forEach((fn()) {
+        try {
+          fn();
+          fail("Expected ArgumentError for $tags");
+        } on ArgumentError catch(e) {

[nweiz, 2015/11/16 21:59:44]

Use the throwsArgumentError matcher here.

[yjbanov, 2015/11/26 06:30:27]

Done.

+          expectArgumentError(e, tags, message);
+        }
+      });
+    }
+
+    test("takes no tags", () {
+      expectTags(null, []);
+      expectTags("", []);
+      expectTags(" ", []);
+      expectTags([], []);
+    });
+
+    test("takes some tags as Iterable", () {
+      var tags = ["a", "b"];
+      expectTags(tags, tags);
+      expectTags(new Set.from(tags), tags);
+    });
+
+    test("takes some tags as String", () {
+      expectTags("a", ["a"]);
+      expectTags("a,b", ["a", "b"]);
+      expectTags(" a,,,b , c\n,d\t", ["a", "b", "c", "d"]);
+    });
+
+    test("parse refuses bad tag types", () {
+      try {
+        new Metadata.parse(tags: 1);
+        fail("Expected ArgumentError for 1");
+      } on ArgumentError catch(e) {
+        expectArgumentError(e, 1,
+            "must be either String or Iterable");
+      }
+    });
+
+    test("refuses non-String tag names", () {
+      expectTagsError(
+          tags: [1],
+          message: "tag name must be String");
+      expectTagsError(
+          tags: [null],
+          message: "tag name must be String");
+    });
+
+    test("refuses blank tag names", () {
+      var errorMsg = "tag name must contain non-whitespace characters";
+      expectTagsError(
+          tags: [""],
+          message: errorMsg);
+      expectTagsError(
+          tags: [" "],
+          message: errorMsg);
+    });
+
+    test("merges tags by computing the union of the two tag sets", () {
+      var merged = new Metadata(tags: ["a", "b"])
+          .merge(new Metadata(tags: ["b", "c"]));
+      expect(merged.tags, unorderedEquals(["a", "b", "c"]));
+    });
+
+    test("serializes tags to a List", () {
+      var serialized = new Metadata(tags: ["a", "b"]).serialize()['tags'];
+      expect(serialized, new isInstanceOf<List>());
+      expect(serialized, ["a", "b"]);
+    });
+  });
+
   group("onPlatform", () {
     test("parses a valid map", () {
       var metadata = new Metadata.parse(onPlatform: {