internal/cuetxtar: Correct nesting of tests

TxTarTest.Run passed the wrong testing.T to TxTarTest.run which led to
confused nesting of tests.

Also, be explicit about use of DebugArchive always causing tests to
error - although that was clear from the code, it was not clear from the
test output.

Signed-off-by: Matthew Sackman <[email protected]>
Change-Id: I2c4d7acabe2eed8d9433d9960533bb50458622e2
Reviewed-on: https://review.gerrithub.io/c/cue-lang/cue/+/1198556
TryBot-Result: CUEcueckoo <[email protected]>
Reviewed-by: Daniel Martí <[email protected]>

internal/cuetxtar/txtar.go

@@ -334,7 +334,7 @@ func (x *TxTarTest) Run(t *testing.T, f func(tc *Test)) {
 		if s := m.Name(); s != cuetdtest.DefaultVersion {
 			test.Name += "-" + s
 		}
-		test.run(t, func(tc *Test) {
+		test.run(m.T, func(tc *Test) {
 			tc.M = m
 			f(tc)
 		})
@@ -379,8 +379,9 @@ func (x *TxTarTest) run(t *testing.T, f func(tc *Test)) {
 
 			f(tc)
 
-			// Unconditionally output as an error.
-			t.Error(tc.buf.String())
+			// Unconditionally log the output and fail.
+			t.Log(tc.buf.String())
+			t.Error("DebugArchive tests always fail")
 		})
 		return
 	}