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 <[email protected]>
Reviewed-on: https://review.gerrithub.io/c/cue-lang/cue/+/540482
Unity-Result: CUEcueckoo <[email protected]>
TryBot-Result: CUEcueckoo <[email protected]>
Reviewed-by: Roger Peppe <[email protected]>

Author: mvdan

Diff for: 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)
 			}
 		})
 	}

Diff for: 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)
 			}
 		})

Diff for: 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 {

Diff for: 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)
 			}
 		})
 	}

Diff for: 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)
 	}
 }
 

Diff for: 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)
 			}

Diff for: 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)
 			}
 		})
 	}

Diff for: 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)

Diff for: 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)
 			}
 		})
 	}

Diff for: 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)

Diff for: 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)
 	}
 }
 

Diff for: 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)
 			}
 		})
 	}

Diff for: 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: