Add acceptance/selftest, showcasing basic features

Make TestInprocessMode use this test.

acceptance/acceptance_test.go

@@ -60,12 +60,7 @@ func TestInprocessMode(t *testing.T) {
 	if InprocessMode {
 		t.Skip("Already tested by TestAccept")
 	}
-	if runtime.GOOS == "windows" {
-		// -  catalogs                               A catalog is the first layer of Unity Catalog’s three-level namespace.
-		// +  catalogs                               A catalog is the first layer of Unity Catalog<6F>s three-level namespace.
-		t.Skip("Fails on CI on unicode characters")
-	}
-	require.NotZero(t, testAccept(t, true, "help"))
+	require.NotZero(t, testAccept(t, true, "selftest"))
 }
 
 func testAccept(t *testing.T, InprocessMode bool, singleTest string) int {

acceptance/selftest/out.hello.txt

@@ -0,0 +1 @@
+HELLO

acceptance/selftest/output.txt

@@ -0,0 +1,30 @@
+=== Capturing STDERR
+>>> python3 -c import sys; sys.stderr.write("STDERR\n")
+STDERR
+
+=== Capturing STDOUT
+>>> python3 -c import sys; sys.stderr.write("STDOUT\n")
+STDOUT
+
+=== Capturing exit code
+>>> errcode python3 -c raise SystemExit(5)
+
+Exit code: 5
+
+=== Capturing exit code (alt)
+>>> python3 -c raise SystemExit(7)
+
+Exit code: 7
+
+=== Capturing pwd
+>>> pwd
+$TMPDIR
+
+=== Capturing subdir
+>>> mkdir -p subdir/a/b/c
+
+>>> withdir subdir/a/b/c pwd
+$TMPDIR/subdir/a/b/c
+
+=== Custom output files - everything starting with out is captured and compared
+>>> echo HELLO

acceptance/selftest/script

@@ -0,0 +1,21 @@
+printf "=== Capturing STDERR"
+trace python3 -c 'import sys; sys.stderr.write("STDERR\n")'
+
+printf "\n=== Capturing STDOUT"
+trace python3 -c 'import sys; sys.stderr.write("STDOUT\n")'
+
+printf "\n=== Capturing exit code"
+trace errcode python3 -c 'raise SystemExit(5)'
+
+printf "\n=== Capturing exit code (alt)"
+errcode trace python3 -c 'raise SystemExit(7)'
+
+printf "\n=== Capturing pwd"
+trace pwd
+
+printf "\n=== Capturing subdir"
+trace mkdir -p subdir/a/b/c
+trace withdir subdir/a/b/c pwd | sed 's/\\/\//g'
+
+printf "\n=== Custom output files - everything starting with out is captured and compared"
+trace echo HELLO > out.hello.txt