cmd/internal/test2json: generate and validate test artifacts

Adds a mechanism for generating test2json test artifacts from and validating them against a real test. If a .test file has a corresponding .src file, TestGolden will now treat the .src file as a script test, executing it and verifying that the output matches the contents of the .test file. Running TestGolden with the -update flag will also regenerate .test files if they have a corresponding .src file.

Capturing the output of the script test in this way required making minor changes to cmd/internal/script/scripttest.

This was motivated by CL 601535 (golang/go#62728). Specifically, testing that CL required adding src/cmd/internal/test2json/testdata/frameescape.test which has a multitude of non-printing characters and thus must be generated by executing `go test`. Using a script test to generate the test file is more reliable than doing it by hand.

Change-Id: I60456700e37e21a42d0514be2ce86dc6df2bccb0
Reviewed-on: https://go-review.googlesource.com/c/go/+/628615
Reviewed-by: Michael Matloob <matloob@golang.org>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Michael Matloob <matloob@google.com>
Reviewed-by: Damien Neil <dneil@google.com>
Auto-Submit: Damien Neil <dneil@google.com>

3 files changed, 50 insertions, 0 deletions

diff --git a/src/cmd/internal/test2json/testdata/README.md b/src/cmd/internal/test2json/testdata/README.md
new file mode 100644
index 0000000000..e86c88f51c
--- /dev/null
+++ b/src/cmd/internal/test2json/testdata/README.md
@@ -0,0 +1,11 @@
+# test2json test artifacts
+
+This directory contains test artifacts for `TestGolden` in
+[test2json_test.go](../test2json_test.go). For each set of `<test>.*` files:
+
+- If `<test>.src` is present, TestGolden executes it as a script test and verifies
+  that the output matches `<test>.test`. This verifies that the testing package
+  produces the output expected by test2json.
+- TestGolden reads `<test>.test` and processes it with a `Converter`, verifying
+  that the output matches `<test>.json`.This verifies that test2json produces
+  the expected output events.
\ No newline at end of file
diff --git a/src/cmd/internal/test2json/testdata/frameescape.src b/src/cmd/internal/test2json/testdata/frameescape.src
new file mode 100644
index 0000000000..4bad6dac77
--- /dev/null
+++ b/src/cmd/internal/test2json/testdata/frameescape.src
@@ -0,0 +1,24 @@
+! go test -v=test2json
+
+stdout '=== RUN   TestAscii'
+
+-- go.mod --
+module p
+
+-- x_test.go --
+package p
+
+import "testing"
+
+func TestAscii(t *testing.T) {
+	t.Run("Log", func(t *testing.T) {
+		for i := rune(0); i < 0x80; i++ {
+			t.Log(string(i))
+		}
+	})
+	t.Run("Error", func(t *testing.T) {
+		for i := rune(0); i < 0x80; i++ {
+			t.Error(string(i))
+		}
+	})
+}
diff --git a/src/cmd/internal/test2json/testdata/multiline-error.src b/src/cmd/internal/test2json/testdata/multiline-error.src
new file mode 100644
index 0000000000..a09570bd82
--- /dev/null
+++ b/src/cmd/internal/test2json/testdata/multiline-error.src
@@ -0,0 +1,15 @@
+! go test -v=test2json
+
+stdout '=== RUN   Test'
+
+-- go.mod --
+module p
+
+-- x_test.go --
+package p
+
+import "testing"
+
+func Test(t *testing.T) {
+	t.Error("Error1\nError2\r")
+}