encoding/xml: add more EncodeToken tests.

There are no behavior changes in this CL, only specifying the status
quo. A follow-up CL, https://go-review.googlesource.com/#/c/2660/, will
change the EncodeToken behavior.

Change-Id: I6ecbcfb05ae681de71fa1099d054df2826ed4acb
Reviewed-on: https://go-review.googlesource.com/4167Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

src/encoding/xml/marshal_test.go

@@ -1194,41 +1194,363 @@ func TestStructPointerMarshal(t *testing.T) {
 }
 
 var encodeTokenTests = []struct {
-	tok  Token
+	desc string
+	toks []Token
 	want string
-	ok   bool
-}{
-	{StartElement{Name{"space", "local"}, nil}, "<local xmlns=\"space\">", true},
-	{StartElement{Name{"space", ""}, nil}, "", false},
-	{EndElement{Name{"space", ""}}, "", false},
-	{CharData("foo"), "foo", true},
-	{Comment("foo"), "<!--foo-->", true},
-	{Comment("foo-->"), "", false},
-	{ProcInst{"Target", []byte("Instruction")}, "<?Target Instruction?>", true},
-	{ProcInst{"", []byte("Instruction")}, "", false},
-	{ProcInst{"Target", []byte("Instruction?>")}, "", false},
-	{Directive("foo"), "<!foo>", true},
-	{Directive("foo>"), "", false},
-}
+	err  string
+}{{
+	desc: "start element with name space",
+	toks: []Token{
+		StartElement{Name{"space", "local"}, nil},
+	},
+	want: `<local xmlns="space">`,
+}, {
+	desc: "start element with no name",
+	toks: []Token{
+		StartElement{Name{"space", ""}, nil},
+	},
+	err: "xml: start tag with no name",
+}, {
+	desc: "end element with no name",
+	toks: []Token{
+		EndElement{Name{"space", ""}},
+	},
+	err: "xml: end tag with no name",
+}, {
+	desc: "char data",
+	toks: []Token{
+		CharData("foo"),
+	},
+	want: `foo`,
+}, {
+	desc: "char data with escaped chars",
+	toks: []Token{
+		CharData(" \t\n"),
+	},
+	want: ` &#x9;&#xA;`,
+}, {
+	desc: "comment",
+	toks: []Token{
+		Comment("foo"),
+	},
+	want: `<!--foo-->`,
+}, {
+	desc: "comment with invalid content",
+	toks: []Token{
+		Comment("foo-->"),
+	},
+	err: "xml: EncodeToken of Comment containing --> marker",
+}, {
+	desc: "proc instruction",
+	toks: []Token{
+		ProcInst{"Target", []byte("Instruction")},
+	},
+	want: `<?Target Instruction?>`,
+}, {
+	desc: "proc instruction with empty target",
+	toks: []Token{
+		ProcInst{"", []byte("Instruction")},
+	},
+	err: "xml: EncodeToken of ProcInst with invalid Target",
+}, {
+	desc: "proc instruction with bad content",
+	toks: []Token{
+		ProcInst{"", []byte("Instruction?>")},
+	},
+	err: "xml: EncodeToken of ProcInst with invalid Target",
+}, {
+	desc: "directive",
+	toks: []Token{
+		Directive("foo"),
+	},
+	want: `<!foo>`,
+}, {
+	desc: "directive instruction with bad name",
+	toks: []Token{
+		Directive("foo>"),
+	},
+	err: "xml: EncodeToken of Directive containing > marker",
+}, {
+	desc: "end tag without start tag",
+	toks: []Token{
+		EndElement{Name{"foo", "bar"}},
+	},
+	err: "xml: end tag </bar> without start tag",
+}, {
+	desc: "mismatching end tag local name",
+	toks: []Token{
+		StartElement{Name{"", "foo"}, nil},
+		EndElement{Name{"", "bar"}},
+	},
+	err:  "xml: end tag </bar> does not match start tag <foo>",
+	want: `<foo>`,
+}, {
+	desc: "mismatching end tag namespace",
+	toks: []Token{
+		StartElement{Name{"space", "foo"}, nil},
+		EndElement{Name{"another", "foo"}},
+	},
+	err:  "xml: end tag </foo> in namespace another does not match start tag <foo> in namespace space",
+	want: `<foo xmlns="space">`,
+}, {
+	desc: "start element with explicit namespace",
+	toks: []Token{
+		StartElement{Name{"space", "local"}, []Attr{
+			{Name{"xmlns", "x"}, "space"},
+			{Name{"space", "foo"}, "value"},
+		}},
+	},
+	want: `<local xmlns="space" xmlns:_xmlns="xmlns" _xmlns:x="space" xmlns:space="space" space:foo="value">`,
+}, {
+	desc: "start element with explicit namespace and colliding prefix",
+	toks: []Token{
+		StartElement{Name{"space", "local"}, []Attr{
+			{Name{"xmlns", "x"}, "space"},
+			{Name{"space", "foo"}, "value"},
+			{Name{"x", "bar"}, "other"},
+		}},
+	},
+	want: `<local xmlns="space" xmlns:_xmlns="xmlns" _xmlns:x="space" xmlns:space="space" space:foo="value" xmlns:x="x" x:bar="other">`,
+}, {
+	desc: "start element using previously defined namespace",
+	toks: []Token{
+		StartElement{Name{"", "local"}, []Attr{
+			{Name{"xmlns", "x"}, "space"},
+		}},
+		StartElement{Name{"space", "foo"}, []Attr{
+			{Name{"space", "x"}, "y"},
+		}},
+	},
+	want: `<local xmlns:_xmlns="xmlns" _xmlns:x="space"><foo xmlns="space" xmlns:space="space" space:x="y">`,
+}, {
+	desc: "nested name space with same prefix",
+	toks: []Token{
+		StartElement{Name{"", "foo"}, []Attr{
+			{Name{"xmlns", "x"}, "space1"},
+		}},
+		StartElement{Name{"", "foo"}, []Attr{
+			{Name{"xmlns", "x"}, "space2"},
+		}},
+		StartElement{Name{"", "foo"}, []Attr{
+			{Name{"space1", "a"}, "space1 value"},
+			{Name{"space2", "b"}, "space2 value"},
+		}},
+		EndElement{Name{"", "foo"}},
+		EndElement{Name{"", "foo"}},
+		StartElement{Name{"", "foo"}, []Attr{
+			{Name{"space1", "a"}, "space1 value"},
+			{Name{"space2", "b"}, "space2 value"},
+		}},
+	},
+	want: `<foo xmlns:_xmlns="xmlns" _xmlns:x="space1"><foo _xmlns:x="space2"><foo xmlns:space1="space1" space1:a="space1 value" xmlns:space2="space2" space2:b="space2 value"></foo></foo><foo xmlns:space1="space1" space1:a="space1 value" xmlns:space2="space2" space2:b="space2 value">`,
+}, {
+	desc: "start element defining several prefixes for the same name space",
+	toks: []Token{
+		StartElement{Name{"space", "foo"}, []Attr{
+			{Name{"xmlns", "a"}, "space"},
+			{Name{"xmlns", "b"}, "space"},
+			{Name{"space", "x"}, "value"},
+		}},
+	},
+	want: `<foo xmlns="space" xmlns:_xmlns="xmlns" _xmlns:a="space" _xmlns:b="space" xmlns:space="space" space:x="value">`,
+}, {
+	desc: "nested element redefines name space",
+	toks: []Token{
+		StartElement{Name{"", "foo"}, []Attr{
+			{Name{"xmlns", "x"}, "space"},
+		}},
+		StartElement{Name{"space", "foo"}, []Attr{
+			{Name{"xmlns", "y"}, "space"},
+			{Name{"space", "a"}, "value"},
+		}},
+	},
+	want: `<foo xmlns:_xmlns="xmlns" _xmlns:x="space"><foo xmlns="space" _xmlns:y="space" xmlns:space="space" space:a="value">`,
+}, {
+	desc: "nested element creates alias for default name space",
+	toks: []Token{
+		StartElement{Name{"space", "foo"}, []Attr{
+			{Name{"", "xmlns"}, "space"},
+		}},
+		StartElement{Name{"space", "foo"}, []Attr{
+			{Name{"xmlns", "y"}, "space"},
+			{Name{"space", "a"}, "value"},
+		}},
+	},
+	want: `<foo xmlns="space" xmlns="space"><foo xmlns="space" xmlns:_xmlns="xmlns" _xmlns:y="space" xmlns:space="space" space:a="value">`,
+}, {
+	desc: "nested element defines default name space with existing prefix",
+	toks: []Token{
+		StartElement{Name{"", "foo"}, []Attr{
+			{Name{"xmlns", "x"}, "space"},
+		}},
+		StartElement{Name{"space", "foo"}, []Attr{
+			{Name{"", "xmlns"}, "space"},
+			{Name{"space", "a"}, "value"},
+		}},
+	},
+	want: `<foo xmlns:_xmlns="xmlns" _xmlns:x="space"><foo xmlns="space" xmlns="space" xmlns:space="space" space:a="value">`,
+}, {
+	desc: "nested element uses empty attribute name space when default ns defined",
+	toks: []Token{
+		StartElement{Name{"space", "foo"}, []Attr{
+			{Name{"", "xmlns"}, "space"},
+		}},
+		StartElement{Name{"space", "foo"}, []Attr{
+			{Name{"", "attr"}, "value"},
+		}},
+	},
+	want: `<foo xmlns="space" xmlns="space"><foo xmlns="space" attr="value">`,
+}, {
+	desc: "redefine xmlns",
+	toks: []Token{
+		StartElement{Name{"", "foo"}, []Attr{
+			{Name{"foo", "xmlns"}, "space"},
+		}},
+	},
+	want: `<foo xmlns:foo="foo" foo:xmlns="space">`,
+}, {
+	desc: "xmlns with explicit name space #1",
+	toks: []Token{
+		StartElement{Name{"space", "foo"}, []Attr{
+			{Name{"xml", "xmlns"}, "space"},
+		}},
+	},
+	want: `<foo xmlns="space" xmlns:_xml="xml" _xml:xmlns="space">`,
+}, {
+	desc: "xmlns with explicit name space #2",
+	toks: []Token{
+		StartElement{Name{"space", "foo"}, []Attr{
+			{Name{xmlURL, "xmlns"}, "space"},
+		}},
+	},
+	want: `<foo xmlns="space" xml:xmlns="space">`,
+}, {
+	desc: "empty name space declaration is ignored",
+	toks: []Token{
+		StartElement{Name{"", "foo"}, []Attr{
+			{Name{"xmlns", "foo"}, ""},
+		}},
+	},
+	want: `<foo xmlns:_xmlns="xmlns" _xmlns:foo="">`,
+}, {
+	desc: "attribute with no name is ignored",
+	toks: []Token{
+		StartElement{Name{"", "foo"}, []Attr{
+			{Name{"", ""}, "value"},
+		}},
+	},
+	want: `<foo>`,
+}, {
+	desc: "namespace URL with non-valid name",
+	toks: []Token{
+		StartElement{Name{"/34", "foo"}, []Attr{
+			{Name{"/34", "x"}, "value"},
+		}},
+	},
+	want: `<foo xmlns="/34" xmlns:_="/34" _:x="value">`,
+}, {
+	desc: "nested element resets default namespace to empty",
+	toks: []Token{
+		StartElement{Name{"space", "foo"}, []Attr{
+			{Name{"", "xmlns"}, "space"},
+		}},
+		StartElement{Name{"", "foo"}, []Attr{
+			{Name{"", "xmlns"}, ""},
+			{Name{"", "x"}, "value"},
+			{Name{"space", "x"}, "value"},
+		}},
+	},
+	want: `<foo xmlns="space" xmlns="space"><foo xmlns="" x="value" xmlns:space="space" space:x="value">`,
+}, {
+	desc: "nested element requires empty default name space",
+	toks: []Token{
+		StartElement{Name{"space", "foo"}, []Attr{
+			{Name{"", "xmlns"}, "space"},
+		}},
+		StartElement{Name{"", "foo"}, nil},
+	},
+	want: `<foo xmlns="space" xmlns="space"><foo>`,
+}, {
+	desc: "attribute uses name space from xmlns",
+	toks: []Token{
+		StartElement{Name{"some/space", "foo"}, []Attr{
+			{Name{"", "attr"}, "value"},
+			{Name{"some/space", "other"}, "other value"},
+		}},
+	},
+	want: `<foo xmlns="some/space" attr="value" xmlns:space="some/space" space:other="other value">`,
+}, {
+	desc: "default name space should not be used by attributes",
+	toks: []Token{
+		StartElement{Name{"space", "foo"}, []Attr{
+			{Name{"", "xmlns"}, "space"},
+			{Name{"xmlns", "bar"}, "space"},
+			{Name{"space", "baz"}, "foo"},
+		}},
+		StartElement{Name{"space", "baz"}, nil},
+		EndElement{Name{"space", "baz"}},
+		EndElement{Name{"space", "foo"}},
+	},
+	want: `<foo xmlns="space" xmlns="space" xmlns:_xmlns="xmlns" _xmlns:bar="space" xmlns:space="space" space:baz="foo"><baz xmlns="space"></baz></foo>`,
+}, {
+	desc: "default name space not used by attributes, not explicitly defined",
+	toks: []Token{
+		StartElement{Name{"space", "foo"}, []Attr{
+			{Name{"", "xmlns"}, "space"},
+			{Name{"space", "baz"}, "foo"},
+		}},
+		StartElement{Name{"space", "baz"}, nil},
+		EndElement{Name{"space", "baz"}},
+		EndElement{Name{"space", "foo"}},
+	},
+	want: `<foo xmlns="space" xmlns="space" xmlns:space="space" space:baz="foo"><baz xmlns="space"></baz></foo>`,
+}, {
+	desc: "impossible xmlns declaration",
+	toks: []Token{
+		StartElement{Name{"", "foo"}, []Attr{
+			{Name{"", "xmlns"}, "space"},
+		}},
+		StartElement{Name{"space", "bar"}, []Attr{
+			{Name{"space", "attr"}, "value"},
+		}},
+	},
+	want: `<foo xmlns="space"><bar xmlns="space" xmlns:space="space" space:attr="value">`,
+}}
 
 func TestEncodeToken(t *testing.T) {
-	for _, tt := range encodeTokenTests {
+loop:
+	for i, tt := range encodeTokenTests {
 		var buf bytes.Buffer
 		enc := NewEncoder(&buf)
-		err := enc.EncodeToken(tt.tok)
+		var err error
+		for j, tok := range tt.toks {
+			err = enc.EncodeToken(tok)
+			if err != nil && j < len(tt.toks)-1 {
+				t.Errorf("#%d %s token #%d: %v", i, tt.desc, j, err)
+				continue loop
+			}
+		}
+		errorf := func(f string, a ...interface{}) {
+			t.Errorf("#%d %s token #%d:%s", i, tt.desc, len(tt.toks)-1, fmt.Sprintf(f, a...))
+		}
 		switch {
-		case !tt.ok && err == nil:
-			t.Errorf("enc.EncodeToken(%#v): expected error; got none", tt.tok)
-		case tt.ok && err != nil:
-			t.Fatalf("enc.EncodeToken: %v", err)
-		case !tt.ok && err != nil:
-			// expected error, got one
+		case tt.err != "" && err == nil:
+			errorf(" expected error; got none")
+			continue
+		case tt.err == "" && err != nil:
+			errorf(" got error: %v", err)
+			continue
+		case tt.err != "" && err != nil && tt.err != err.Error():
+			errorf(" error mismatch; got %v, want %v", err, tt.err)
+			continue
 		}
 		if err := enc.Flush(); err != nil {
-			t.Fatalf("enc.EncodeToken: %v", err)
+			errorf(" %v", err)
+			continue
 		}
 		if got := buf.String(); got != tt.want {
-			t.Errorf("enc.EncodeToken = %s; want: %s", got, tt.want)
+			errorf("\ngot  %v\nwant %v", got, tt.want)
+			continue
 		}
 	}
 }