1 files changed, 57 insertions, 0 deletions
diff --git a/gopls/internal/span/span_test.go b/gopls/internal/span/span_test.go
new file mode 100644
index 000000000..d2aaff12c
--- /dev/null
+++ b/gopls/internal/span/span_test.go
@@ -0,0 +1,57 @@
+// Copyright 2019 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package span_test
+
+import (
+	"fmt"
+	"path/filepath"
+	"strings"
+	"testing"
+
+	"golang.org/x/tools/gopls/internal/span"
+)
+
+func TestFormat(t *testing.T) {
+	formats := []string{"%v", "%#v", "%+v"}
+
+	// Element 0 is the input, and the elements 0-2 are the expected
+	// output in [%v %#v %+v] formats. Thus the first must be in
+	// canonical form (invariant under span.Parse + fmt.Sprint).
+	// The '#' form displays offsets; the '+' form outputs a URI.
+	// If len=4, element 0 is a noncanonical input and 1-3 are expected outputs.
+	for _, test := range [][]string{
+		{"C:/file_a", "C:/file_a", "file:///C:/file_a:#0"},
+		{"C:/file_b:1:2", "C:/file_b:1:2", "file:///C:/file_b:1:2"},
+		{"C:/file_c:1000", "C:/file_c:1000", "file:///C:/file_c:1000:1"},
+		{"C:/file_d:14:9", "C:/file_d:14:9", "file:///C:/file_d:14:9"},
+		{"C:/file_e:1:2-7", "C:/file_e:1:2-7", "file:///C:/file_e:1:2-1:7"},
+		{"C:/file_f:500-502", "C:/file_f:500-502", "file:///C:/file_f:500:1-502:1"},
+		{"C:/file_g:3:7-8", "C:/file_g:3:7-8", "file:///C:/file_g:3:7-3:8"},
+		{"C:/file_h:3:7-4:8", "C:/file_h:3:7-4:8", "file:///C:/file_h:3:7-4:8"},
+		{"C:/file_i:#100", "C:/file_i:#100", "file:///C:/file_i:#100"},
+		{"C:/file_j:#26-#28", "C:/file_j:#26-#28", "file:///C:/file_j:#26-0#28"}, // 0#28?
+		{"C:/file_h:3:7#26-4:8#37", // not canonical
+			"C:/file_h:3:7-4:8", "C:/file_h:#26-#37", "file:///C:/file_h:3:7#26-4:8#37"}} {
+		input := test[0]
+		spn := span.Parse(input)
+		wants := test[0:3]
+		if len(test) == 4 {
+			wants = test[1:4]
+		}
+		for i, format := range formats {
+			want := toPath(wants[i])
+			if got := fmt.Sprintf(format, spn); got != want {
+				t.Errorf("Sprintf(%q, %q) = %q, want %q", format, input, got, want)
+			}
+		}
+	}
+}
+
+func toPath(value string) string {
+	if strings.HasPrefix(value, "file://") {
+		return value
+	}
+	return filepath.FromSlash(value)
+}