internal/lsp: merge diffing test data sets

also improve the actual verification of the unified diff

Change-Id: I9c23c24e1fc8571cce2a7879463659ec7069fe99
Reviewed-on: https://go-review.googlesource.com/c/tools/+/199738
Run-TryBot: Ian Cottrell <iancottrell@google.com>
Reviewed-by: Rebecca Stambler <rstambler@golang.org>

internal/lsp/diff/diff_test.go

@@ -4,27 +4,16 @@ import (
 	"testing"
 
 	"golang.org/x/tools/internal/lsp/diff"
-	"golang.org/x/tools/internal/span"
+	"golang.org/x/tools/internal/lsp/diff/difftest"
 )
 
 func TestApplyEdits(t *testing.T) {
-	var testCases = []struct {
-		before string
-		edits  []diff.TextEdit
-		want   string
-	}{
-		{"", nil, ""},
-		{"X", []diff.TextEdit{{newSpan(0, 1), "Y"}}, "Y"},
-		{" X ", []diff.TextEdit{{newSpan(1, 2), "Y"}}, " Y "},
-		{" X X ", []diff.TextEdit{{newSpan(1, 2), "Y"}, {newSpan(3, 4), "Z"}}, " Y Z "},
-	}
-	for _, tc := range testCases {
-		if got := diff.ApplyEdits(tc.before, tc.edits); got != tc.want {
-			t.Errorf("applyEdits(%v, %v): got %v, want %v", tc.before, tc.edits, got, tc.want)
-		}
+	for _, tc := range difftest.TestCases {
+		t.Run(tc.Name, func(t *testing.T) {
+			t.Helper()
+			if got := diff.ApplyEdits(tc.In, tc.Edits); got != tc.Out {
+				t.Errorf("ApplyEdits edits got %q, want %q", got, tc.Out)
+			}
+		})
 	}
 }
-
-func newSpan(start, end int) span.Span {
-	return span.New("", span.NewPoint(0, 0, start), span.NewPoint(0, 0, end))
-}

internal/lsp/diff/difftest/difftest.go

@@ -8,12 +8,7 @@
 package difftest
 
 import (
-	"flag"
 	"fmt"
-	"io/ioutil"
-	"os"
-	"os/exec"
-	"strings"
 	"testing"
 
 	"golang.org/x/tools/internal/lsp/diff"
@@ -21,88 +16,104 @@ import (
 )
 
 const (
-	fileA         = "from"
-	fileB         = "to"
-	unifiedPrefix = "--- " + fileA + "\n+++ " + fileB + "\n"
+	FileA         = "from"
+	FileB         = "to"
+	UnifiedPrefix = "--- " + FileA + "\n+++ " + FileB + "\n"
 )
 
-var verifyDiff = flag.Bool("verify-diff", false, "Check that the unified diff output matches `diff -u`")
-
-func DiffTest(t *testing.T, compute diff.ComputeEdits) {
-	t.Helper()
-	for _, test := range []struct {
-		name, in, out, unified string
-		nodiff                 bool
-	}{{
-		name: "empty",
-		in:   "",
-		out:  "",
-	}, {
-		name: "no_diff",
-		in:   "gargantuan\n",
-		out:  "gargantuan\n",
-	}, {
-		name: "replace_all",
-		in:   "gord\n",
-		out:  "gourd\n",
-		unified: unifiedPrefix + `
+var TestCases = []struct {
+	Name, In, Out, Unified string
+	Edits                  []diff.TextEdit
+	NoDiff                 bool
+}{{
+	Name: "empty",
+	In:   "",
+	Out:  "",
+}, {
+	Name: "no_diff",
+	In:   "gargantuan\n",
+	Out:  "gargantuan\n",
+}, {
+	Name: "replace_all",
+	In:   "fruit\n",
+	Out:  "cheese\n",
+	Unified: UnifiedPrefix + `
+@@ -1 +1 @@
+-fruit
++cheese
+`[1:],
+	Edits: []diff.TextEdit{{Span: newSpan(0, 5), NewText: "cheese"}},
+}, {
+	Name: "insert_rune",
+	In:   "gord\n",
+	Out:  "gourd\n",
+	Unified: UnifiedPrefix + `
 @@ -1 +1 @@
 -gord
 +gourd
 `[1:],
-	}, {
-		name: "insert_rune",
-		in:   "gord\n",
-		out:  "gourd\n",
-		unified: unifiedPrefix + `
-@@ -1 +1 @@
--gord
-+gourd
-`[1:],
-	}, {
-		name: "delete_rune",
-		in:   "groat\n",
-		out:  "goat\n",
-		unified: unifiedPrefix + `
+	Edits: []diff.TextEdit{{Span: newSpan(2, 2), NewText: "u"}},
+}, {
+	Name: "delete_rune",
+	In:   "groat\n",
+	Out:  "goat\n",
+	Unified: UnifiedPrefix + `
 @@ -1 +1 @@
 -groat
 +goat
 `[1:],
-	}, {
-		name: "replace_rune",
-		in:   "loud\n",
-		out:  "lord\n",
-		unified: unifiedPrefix + `
+	Edits: []diff.TextEdit{{Span: newSpan(1, 2), NewText: ""}},
+}, {
+	Name: "replace_rune",
+	In:   "loud\n",
+	Out:  "lord\n",
+	Unified: UnifiedPrefix + `
 @@ -1 +1 @@
 -loud
 +lord
 `[1:],
-	}, {
-		name: "insert_line",
-		in:   "one\nthree\n",
-		out:  "one\ntwo\nthree\n",
-		unified: unifiedPrefix + `
+	Edits: []diff.TextEdit{{Span: newSpan(2, 3), NewText: "r"}},
+}, {
+	Name: "replace_partials",
+	In:   "blanket\n",
+	Out:  "bunker\n",
+	Unified: UnifiedPrefix + `
+@@ -1 +1 @@
+-blanket
++bunker
+`[1:],
+	Edits: []diff.TextEdit{
+		{Span: newSpan(1, 3), NewText: "u"},
+		{Span: newSpan(6, 7), NewText: "r"},
+	},
+}, {
+	Name: "insert_line",
+	In:   "one\nthree\n",
+	Out:  "one\ntwo\nthree\n",
+	Unified: UnifiedPrefix + `
 @@ -1,2 +1,3 @@
  one
 +two
  three
 `[1:],
-	}, {
-		name: "replace_no_newline",
-		in:   "A",
-		out:  "B",
-		unified: unifiedPrefix + `
+	Edits: []diff.TextEdit{{Span: newSpan(4, 4), NewText: "two\n"}},
+}, {
+	Name: "replace_no_newline",
+	In:   "A",
+	Out:  "B",
+	Unified: UnifiedPrefix + `
 @@ -1 +1 @@
 -A
 \ No newline at end of file
 +B
 \ No newline at end of file
 `[1:],
-	}, {
-		name: "delete_front",
-		in:   "A\nB\nC\nA\nB\nB\nA\n",
-		out:  "C\nB\nA\nB\nA\nC\n",
-		unified: unifiedPrefix + `
+	Edits: []diff.TextEdit{{Span: newSpan(0, 1), NewText: "B"}},
+}, {
+	Name: "delete_front",
+	In:   "A\nB\nC\nA\nB\nB\nA\n",
+	Out:  "C\nB\nA\nB\nA\nC\n",
+	Unified: UnifiedPrefix + `
 @@ -1,7 +1,6 @@
 -A
 -B
@@ -114,25 +125,32 @@ func DiffTest(t *testing.T, compute diff.ComputeEdits) {
  A
 +C
 `[1:],
-		nodiff: true, // diff algorithm produces different delete/insert pattern
+	Edits: []diff.TextEdit{
+		{Span: newSpan(0, 4), NewText: ""},
+		{Span: newSpan(6, 6), NewText: "B\n"},
+		{Span: newSpan(10, 12), NewText: ""},
+		{Span: newSpan(14, 14), NewText: "C\n"},
 	},
-		{
-			name: "replace_last_line",
-			in:   "A\nB\n",
-			out:  "A\nC\n\n",
-			unified: unifiedPrefix + `
+	NoDiff: true, // diff algorithm produces different delete/insert pattern
+},
+	{
+		Name: "replace_last_line",
+		In:   "A\nB\n",
+		Out:  "A\nC\n\n",
+		Unified: UnifiedPrefix + `
 @@ -1,2 +1,3 @@
  A
 -B
 +C
 +
 `[1:],
-		},
-		{
-			name: "mulitple_replace",
-			in:   "A\nB\nC\nD\nE\nF\nG\n",
-			out:  "A\nH\nI\nJ\nE\nF\nK\n",
-			unified: unifiedPrefix + `
+		Edits: []diff.TextEdit{{Span: newSpan(2, 3), NewText: "C\n"}},
+	},
+	{
+		Name: "mulitple_replace",
+		In:   "A\nB\nC\nD\nE\nF\nG\n",
+		Out:  "A\nH\nI\nJ\nE\nF\nK\n",
+		Unified: UnifiedPrefix + `
 @@ -1,7 +1,7 @@
  A
 -B
@@ -146,71 +164,42 @@ func DiffTest(t *testing.T, compute diff.ComputeEdits) {
 -G
 +K
 `[1:],
-		}} {
-		t.Run(test.name, func(t *testing.T) {
+		Edits: []diff.TextEdit{
+			{Span: newSpan(2, 8), NewText: "H\nI\nJ\n"},
+			{Span: newSpan(12, 14), NewText: "K\n"},
+		},
+	},
+}
+
+func init() {
+	// expand all the spans to full versions
+	// we need them all to have their line number and column
+	for _, tc := range TestCases {
+		c := span.NewContentConverter("", []byte(tc.In))
+		for i := range tc.Edits {
+			tc.Edits[i].Span, _ = tc.Edits[i].Span.WithAll(c)
+		}
+	}
+}
+
+func DiffTest(t *testing.T, compute diff.ComputeEdits) {
+	t.Helper()
+	for _, test := range TestCases {
+		t.Run(test.Name, func(t *testing.T) {
 			t.Helper()
-			edits := compute(span.FileURI("/"+test.name), test.in, test.out)
-			got := diff.ApplyEdits(test.in, edits)
-			unified := fmt.Sprint(diff.ToUnified("from", "to", test.in, edits))
-			if got != test.out {
-				t.Errorf("got patched:\n%v\nfrom diff:\n%v\nexpected:\n%v", got, unified, test.out)
+			edits := compute(span.FileURI("/"+test.Name), test.In, test.Out)
+			got := diff.ApplyEdits(test.In, edits)
+			unified := fmt.Sprint(diff.ToUnified(FileA, FileB, test.In, edits))
+			if got != test.Out {
+				t.Errorf("got patched:\n%v\nfrom diff:\n%v\nexpected:\n%v", got, unified, test.Out)
 			}
-			if unified != test.unified {
-				t.Errorf("got diff:\n%v\nexpected:\n%v", unified, test.unified)
-			}
-			if *verifyDiff && !test.nodiff {
-				diff, err := getDiffOutput(test.in, test.out)
-				if err != nil {
-					t.Fatal(err)
-				}
-				if len(diff) > 0 {
-					diff = unifiedPrefix + diff
-				}
-				if diff != test.unified {
-					t.Errorf("unified:\n%q\ndiff -u:\n%q", test.unified, diff)
-				}
+			if unified != test.Unified {
+				t.Errorf("got diff:\n%v\nexpected:\n%v", unified, test.Unified)
 			}
 		})
 	}
 }
 
-func getDiffOutput(a, b string) (string, error) {
-	fileA, err := ioutil.TempFile("", "myers.in")
-	if err != nil {
-		return "", err
-	}
-	defer os.Remove(fileA.Name())
-	if _, err := fileA.Write([]byte(a)); err != nil {
-		return "", err
-	}
-	if err := fileA.Close(); err != nil {
-		return "", err
-	}
-	fileB, err := ioutil.TempFile("", "myers.in")
-	if err != nil {
-		return "", err
-	}
-	defer os.Remove(fileB.Name())
-	if _, err := fileB.Write([]byte(b)); err != nil {
-		return "", err
-	}
-	if err := fileB.Close(); err != nil {
-		return "", err
-	}
-	cmd := exec.Command("diff", "-u", fileA.Name(), fileB.Name())
-	out, err := cmd.CombinedOutput()
-	if err != nil {
-		if _, ok := err.(*exec.ExitError); !ok {
-			return "", fmt.Errorf("failed to run diff -u %v %v: %v\n%v", fileA.Name(), fileB.Name(), err, string(out))
-		}
-	}
-	diff := string(out)
-	if len(diff) <= 0 {
-		return diff, nil
-	}
-	bits := strings.SplitN(diff, "\n", 3)
-	if len(bits) != 3 {
-		return "", fmt.Errorf("diff output did not have file prefix:\n%s", diff)
-	}
-	return bits[2], nil
+func newSpan(start, end int) span.Span {
+	return span.New("", span.NewPoint(0, 0, start), span.NewPoint(0, 0, end))
 }

internal/lsp/diff/difftest/difftest_test.go

@@ -0,0 +1,83 @@
+// 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 difftest supplies a set of tests that will operate on any
+// implementation of a diff algorithm as exposed by
+// "golang.org/x/tools/internal/lsp/diff"
+package difftest_test
+
+import (
+	"fmt"
+	"io/ioutil"
+	"os"
+	"os/exec"
+	"strings"
+	"testing"
+
+	"golang.org/x/tools/internal/lsp/diff/difftest"
+	"golang.org/x/tools/internal/testenv"
+)
+
+func VerifyUnifiedTest(t *testing.T) {
+	testenv.NeedsTool(t, "diff")
+	for _, test := range difftest.TestCases {
+		t.Run(test.Name, func(t *testing.T) {
+			t.Helper()
+			if test.NoDiff {
+				t.Skip("diff tool produces expected different results")
+			}
+			diff, err := getDiffOutput(test.In, test.Out)
+			if err != nil {
+				t.Fatal(err)
+			}
+			if len(diff) > 0 {
+				diff = difftest.UnifiedPrefix + diff
+			}
+			if diff != test.Unified {
+				t.Errorf("unified:\n%q\ndiff -u:\n%q", test.Unified, diff)
+			}
+		})
+	}
+}
+
+func getDiffOutput(a, b string) (string, error) {
+	fileA, err := ioutil.TempFile("", "myers.in")
+	if err != nil {
+		return "", err
+	}
+	defer os.Remove(fileA.Name())
+	if _, err := fileA.Write([]byte(a)); err != nil {
+		return "", err
+	}
+	if err := fileA.Close(); err != nil {
+		return "", err
+	}
+	fileB, err := ioutil.TempFile("", "myers.in")
+	if err != nil {
+		return "", err
+	}
+	defer os.Remove(fileB.Name())
+	if _, err := fileB.Write([]byte(b)); err != nil {
+		return "", err
+	}
+	if err := fileB.Close(); err != nil {
+		return "", err
+	}
+	cmd := exec.Command("diff", "-u", fileA.Name(), fileB.Name())
+	out, err := cmd.CombinedOutput()
+	if err != nil {
+		if _, ok := err.(*exec.ExitError); !ok {
+			return "", fmt.Errorf("failed to run diff -u %v %v: %v\n%v", fileA.Name(), fileB.Name(), err, string(out))
+		}
+	}
+	diff := string(out)
+	if len(diff) <= 0 {
+		return diff, nil
+	}
+	bits := strings.SplitN(diff, "\n", 3)
+	if len(bits) != 3 {
+		return "", fmt.Errorf("diff output did not have file prefix:\n%s", diff)
+	}
+	return bits[2], nil
+}