t.Errorf("Opening %q with fs.FS API succeeded", "")
	}
	if _, err := r.Open("test.txt"); err != nil {
		t.Errorf("Error opening %q with fs.FS API: %v", "test.txt", err)
	}
	dirEntries, err := fs.ReadDir(r, ".")
	if err != nil {
		t.Fatalf("Error reading the root directory: %v", err)
	}
	if len(dirEntries) != 1 || dirEntries[0].Name() != "test.txt" {
		t.Errorf("Unexpected directory entries")

		{"a☺b☻c☹d", "b", len("a☺")},               // non-ascii
	}
	for _, test := range testCases {
		actual := LastIndexByte([]byte(test.a), test.b[0])
		if actual != test.i {
			t.Errorf("LastIndexByte(%q,%c) = %v; want %v", test.a, test.b[0], actual, test.i)
		}
	}
}

// test a larger buffer with different sizes and alignments
func TestIndexByteBig(t *testing.T) {
	var n = 1024

	// Hex constant 0x20004000000
	MOVD $2199090364416, R5         // 60058001
	// Hex constant 0xFFFFFE0004000000
	MOVD $-2198956146688, R5        // 38a08001
	// TODO: On GOPPC64={power8,power9}, this is preprocessed into MOVD $-1, R5; RLDC R5, $33, $63, R5.
	//       This only captures the MOVD. Should the RLDC be appended to the encoding by the test?
	// Hex constant 0xFFFFFFFE00000001

	VFMLS	V1.D2, V12.D2, V1.D2            // 81cde14e
	VFMLS	V1.S2, V12.S2, V1.S2            // 81cda10e
	VFMLS	V1.S4, V12.S4, V1.S4            // 81cda14e
	VEXT	$4, V2.B8, V1.B8, V3.B8         // 2320022e
	VEXT	$8, V2.B16, V1.B16, V3.B16      // 2340026e
	VRBIT	V24.B16, V24.B16                // 185b606e
	VRBIT	V24.B8, V24.B8                  // 185b602e
	VUSHR	$56, V1.D2, V2.D2               // 2204486f

// the old assembler's (5a's) grammar and hand-writing complete
// instructions for each rule, to guarantee we cover the same space.

#include "../../../../../runtime/textflag.h"

TEXT	foo(SB), DUPOK|NOSPLIT, $0

// ADD
//
//	LTYPE1 cond imsr ',' spreg ',' reg
//	{
//		outcode($1, $2, &$3, $5, &$7);
//	}
// Cover some operand space here too.
	ADD	$1, R2, R3
	ADD	R1<<R2, R3, R4

		return true
	}
	return false
}

// Comment from Darwin's CFInternal.h
/*
// Tagged pointer support
// Low-bit set means tagged object, next 3 bits (currently)
// define the tagged object class, next 4 bits are for type
// information for the specific tagged object class.  Thus,
// the low byte is for type info, and the rest of a pointer