all: use go-cmp.Diff more consistently

There's no need to first call cmp.Equal and then cmp.Diff;
use cmp.Diff alone, and test whether the diff is empty.

Also prefer cmp.Diff over pretty.Diff, for the sake of consistency and
fewer dependencies in the future. Note that we still need kr/pretty for
pretty.Print, which has no equivalent in go-cmp.

Change-Id: I9701b588822ac9c490e514e6767aebf26b044931
Signed-off-by: Daniel Martí <mvdan@mvdan.cc>
Reviewed-on: https://review.gerrithub.io/c/cue-lang/cue/+/540482
Unity-Result: CUEcueckoo <cueckoo@cuelang.org>
TryBot-Result: CUEcueckoo <cueckoo@cuelang.org>
Reviewed-by: Roger Peppe <rogpeppe@gmail.com>

cue/ast/astutil/util_test.go

@@ -66,8 +66,8 @@ func TestImportInfo(t *testing.T) {
 			if err != nil {
 				t.Fatal(err)
 			}
-			if !cmp.Equal(got, tc.want) {
-				t.Error(cmp.Diff(got, tc.want))
+			if diff := cmp.Diff(got, tc.want); diff != "" {
+				t.Error(diff)
 			}
 		})
 	}

cue/decode_test.go

@@ -238,8 +238,8 @@ func TestDecode(t *testing.T) {
 			checkFatal(t, err, tc.err, "init")
 
 			got := reflect.ValueOf(tc.dst).Elem().Interface()
-			if !cmp.Equal(got, tc.want) {
-				t.Error(cmp.Diff(got, tc.want))
+			if diff := cmp.Diff(got, tc.want); diff != "" {
+				t.Error(diff)
 				t.Errorf("\n%#v\n%#v", got, tc.want)
 			}
 		})

cue/literal/num_test.go

@@ -100,8 +100,8 @@ func TestNumbers(t *testing.T) {
 			n.src = ""
 			n.p = 0
 			n.ch = 0
-			if !cmp.Equal(n, tc.n, diffOpts...) {
-				t.Error(cmp.Diff(n, tc.n, diffOpts...))
+			if diff := cmp.Diff(n, tc.n, diffOpts...); diff != "" {
+				t.Error(diff)
 				t.Errorf("%#v, %#v\n", n, tc.n)
 			}
 			if n.String() != tc.norm {

cue/marshal_test.go

@@ -194,8 +194,8 @@ func TestMarshalMultiPackage(t *testing.T) {
 			}
 			got := strValue(insts)
 
-			if !cmp.Equal(got, want) {
-				t.Error(cmp.Diff(got, want))
+			if diff := cmp.Diff(got, want); diff != "" {
+				t.Error(diff)
 			}
 		})
 	}

cue/scanner/scanner_test.go

@@ -506,8 +506,8 @@ func TestRelative(t *testing.T) {
 		got = append(got, fmt.Sprintf("%-7s %-8s %s", pos.RelPos(), tok, lit))
 		pos, tok, lit = S.Scan()
 	}
-	if !cmp.Equal(got, want) {
-		t.Error(cmp.Diff(got, want))
+	if diff := cmp.Diff(got, want); diff != "" {
+		t.Error(diff)
 	}
 }
 

cue/types_test.go

@@ -978,8 +978,8 @@ func TestFill(t *testing.T) {
 
 		w := compileT(t, r, tc.out).Value()
 
-		if !cmp.Equal(goValue(v), goValue(w)) {
-			t.Error(cmp.Diff(goValue(v), goValue(w)))
+		if diff := cmp.Diff(goValue(v), goValue(w)); diff != "" {
+			t.Error(diff)
 			t.Errorf("\ngot:  %s\nwant: %s", v, w)
 		}
 	}
@@ -1239,7 +1239,8 @@ func TestFillPath(t *testing.T) {
 
 			w := compileT(t, r, tc.out).Value()
 
-			if !cmp.Equal(goValue(v), goValue(w)) {
+			if diff := cmp.Diff(goValue(v), goValue(w)); diff != "" {
+				t.Error(diff)
 				t.Error(cmp.Diff(goValue(v), goValue(w)))
 				t.Errorf("\ngot:  %s\nwant: %s", v, w)
 			}

encoding/gocode/gocodec/codec_test.go

@@ -20,7 +20,6 @@ import (
 	"testing"
 
 	"github.com/google/go-cmp/cmp"
-	"github.com/kr/pretty"
 
 	"cuelang.org/go/cue"
 )
@@ -219,8 +218,8 @@ func TestComplete(t *testing.T) {
 
 			err = codec.Complete(v, tc.value)
 			checkErr(t, err, tc.err)
-			if !reflect.DeepEqual(tc.value, tc.result) {
-				t.Error(pretty.Diff(tc.value, tc.result))
+			if diff := cmp.Diff(tc.value, tc.result); diff != "" {
+				t.Error(diff)
 			}
 		})
 	}
@@ -252,8 +251,8 @@ func TestEncode(t *testing.T) {
 			}
 
 			got := reflect.ValueOf(tc.dst).Elem().Interface()
-			if !cmp.Equal(got, tc.want) {
-				t.Error(cmp.Diff(got, tc.want))
+			if diff := cmp.Diff(got, tc.want); diff != "" {
+				t.Error(diff)
 			}
 		})
 	}

encoding/openapi/decode_test.go

@@ -87,8 +87,8 @@ func TestDecode(t *testing.T) {
 			if err != nil {
 				got = []byte(err.Error())
 			}
-			if !cmp.Equal(errout, got) {
-				t.Error(cmp.Diff(string(got), string(errout)))
+			if diff := cmp.Diff(errout, got); diff != "" {
+				t.Error(diff)
 			}
 
 			if expr != nil {
@@ -105,7 +105,8 @@ func TestDecode(t *testing.T) {
 				b = bytes.TrimSpace(b)
 				out = bytes.TrimSpace(out)
 
-				if !cmp.Equal(b, out) {
+				if diff := cmp.Diff(b, out); diff != "" {
+					t.Error(diff)
 					if cuetest.UpdateGoldenFiles {
 						a.Files[outIndex].Data = b
 						b = txtar.Format(a)

encoding/protobuf/protobuf_test.go

@@ -24,7 +24,7 @@ import (
 	"strings"
 	"testing"
 
-	"github.com/kr/pretty"
+	"github.com/google/go-cmp/cmp"
 
 	"cuelang.org/go/cue/ast"
 	"cuelang.org/go/cue/errors"
@@ -67,8 +67,8 @@ func TestExtractDefinitions(t *testing.T) {
 				t.Fatal(err)
 			}
 
-			if desc := pretty.Diff(out.String(), string(b)); len(desc) > 0 {
-				t.Errorf("files differ:\n%v", desc)
+			if diff := cmp.Diff(out.String(), string(b)); diff != "" {
+				t.Error(diff)
 			}
 		})
 	}

internal/core/export/toposort_test.go

@@ -80,7 +80,7 @@ func TestSortArcs(t *testing.T) {
 
 			want := parseFeatures(r, tc.out)[0]
 
-			if !cmp.Equal(keys, want) {
+			if diff := cmp.Diff(keys, want); diff != "" {
 				got := ""
 				for _, f := range keys {
 					got += " " + f.SelectorString(r)

internal/filetypes/filetypes_test.go

@@ -29,8 +29,8 @@ func check(t *testing.T, want, x interface{}, err error) {
 	if err != nil {
 		x = errors.String(err.(errors.Error))
 	}
-	if !cmp.Equal(x, want, cmpopts.EquateEmpty()) {
-		t.Error(cmp.Diff(want, x))
+	if diff := cmp.Diff(x, want, cmpopts.EquateEmpty()); diff != "" {
+		t.Error(diff)
 	}
 }
 

pkg/tool/exec/exec_test.go

@@ -63,8 +63,8 @@ func TestEnv(t *testing.T) {
 				t.Fatal(err)
 			}
 
-			if !cmp.Equal(cmd.Env, tc.env) {
-				t.Error(cmp.Diff(cmd.Env, tc.env))
+			if diff := cmp.Diff(cmd.Env, tc.env); diff != "" {
+				t.Error(diff)
 			}
 		})
 	}

pkg/tool/os/env_test.go

@@ -102,8 +102,8 @@ func TestGetenv(t *testing.T) {
 			}),
 		}
 
-		if !cmp.Equal(got, want, opts...) {
-			t.Error(cmp.Diff(got, want, opts...))
+		if diff := cmp.Diff(got, want, opts...); diff != "" {
+			t.Error(diff)
 		}
 
 		// Errors: