fix-tests: Attempt to fix tests that use HasSubstr()
By comparing the old substring to the new full body, we can do a pretty
good job at creating a new substring.
This is not an exact science. Always carefully examine the newly
generated strings for correctness.
Change-Id: I8bdf591539a32ec42d0444aa054d88a933e4d250
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/47765
Commit-Queue: Ben Clayton <bclayton@chromium.org>
Kokoro: Kokoro <noreply+kokoro@google.com>
Reviewed-by: Antonio Maiorano <amaiorano@google.com>
diff --git a/tools/fix-tests/substr/substr.go b/tools/fix-tests/substr/substr.go
new file mode 100644
index 0000000..d8ed99d
--- /dev/null
+++ b/tools/fix-tests/substr/substr.go
@@ -0,0 +1,52 @@
+// Copyright 2021 The Tint Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package substr
+
+import (
+ diff "github.com/sergi/go-diff/diffmatchpatch"
+)
+
+// Fix attempts to reconstruct substr by comparing it to body.
+// substr is a fuzzy substring of body.
+// Fix returns a new exact substring of body, by calculating a diff of the text.
+// If no match could be made, Fix() returns an empty string.
+func Fix(body, substr string) string {
+ dmp := diff.New()
+
+ diffs := dmp.DiffMain(body, substr, false)
+ if len(diffs) == 0 {
+ return ""
+ }
+
+ front := func() diff.Diff { return diffs[0] }
+ back := func() diff.Diff { return diffs[len(diffs)-1] }
+
+ start, end := 0, len(body)
+
+ // Trim edits that remove text from body start
+ for len(diffs) > 0 && front().Type == diff.DiffDelete {
+ start += len(front().Text)
+ diffs = diffs[1:]
+ }
+
+ // Trim edits that remove text from body end
+ for len(diffs) > 0 && back().Type == diff.DiffDelete {
+ end -= len(back().Text)
+ diffs = diffs[:len(diffs)-1]
+ }
+
+ // New substring is the span for the remainder of the edits
+ return body[start:end]
+}
