internal/lsp: make all the tests work on 1.10

Also improve the error messages from a failing diagnostic tests so you can read
them.

Change-Id: I3554ce5a029de22a55a9636ed26ba02d95fc3246
Reviewed-on: https://go-review.googlesource.com/c/150042
Run-TryBot: Ian Cottrell <iancottrell@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Rebecca Stambler <rstambler@golang.org>

internal/lsp/lsp_test.go

@@ -7,6 +7,7 @@ package lsp
 import (
 	"bytes"
 	"context"
+	"fmt"
 	"go/token"
 	"os/exec"
 	"path/filepath"
@@ -184,7 +185,16 @@ func testDiagnostics(t *testing.T, v *source.View, pkgs []*packages.Package, wan
 			})
 			want := wants[filename]
 			if equal := reflect.DeepEqual(want, got); !equal {
-				t.Errorf("diagnostics failed for %s: (expected: %v), (got: %v)", filepath.Base(filename), want, got)
+				msg := &bytes.Buffer{}
+				fmt.Fprintf(msg, "diagnostics failed for %s: expected:\n", filepath.Base(filename))
+				for _, d := range want {
+					fmt.Fprintf(msg, "  %v\n", d)
+				}
+				fmt.Fprintf(msg, "got:\n")
+				for _, d := range got {
+					fmt.Fprintf(msg, "  %v\n", d)
+				}
+				t.Error(msg.String())
 			}
 		}
 	}

internal/lsp/protocol/printers.go

@@ -37,3 +37,20 @@ func (r Range) Format(f fmt.State, c rune) {
 func (l Location) Format(f fmt.State, c rune) {
 	fmt.Fprintf(f, "%s:%v", l.URI, l.Range)
 }
+
+func (s DiagnosticSeverity) Format(f fmt.State, c rune) {
+	switch s {
+	case SeverityError:
+		fmt.Fprint(f, "Error")
+	case SeverityWarning:
+		fmt.Fprint(f, "Warning")
+	case SeverityInformation:
+		fmt.Fprint(f, "Information")
+	case SeverityHint:
+		fmt.Fprint(f, "Hint")
+	}
+}
+
+func (d Diagnostic) Format(f fmt.State, c rune) {
+	fmt.Fprintf(f, "%v:%v from %v at %v: %v", d.Severity, d.Code, d.Source, d.Range, d.Message)
+}

internal/lsp/testdata/bad/bad.go

@@ -1,5 +1,3 @@
-// +build go1.11
-
 package bad
 
 func stuff() {
@@ -14,8 +12,7 @@ type bob struct {
 }
 
 func _() {
-	var q int
 	_ = &bob{
-		f: q, //@diag("f", "unknown field f in struct literal")
+		f: 0, //@diag("f", "unknown field f in struct literal")
 	}
 }

internal/lsp/testdata/bad/bad_util.go

@@ -1,5 +1,3 @@
-// +build go1.11
-
 package bad
 
 func random2(y int) int {

internal/lsp/testdata/noparse_format/noparse_format.1_10.go.in

@@ -0,0 +1,11 @@
+// +build !go1.11
+
+// This file does not actually test anything
+// on 1.10 the errors are different
+package noparse_format
+
+func what() {
+	// we need a diagnostic below so we have the same count as the main file
+	var b int  //@diag("b", "b declared but not used")
+	if true {}
+}