feat(verify): add universal --fuzz differential testing driven by // func signatures

Assisted-by: Qwen 3.8 Max Preview

verify/fuzz_test.go

@@ -0,0 +1,98 @@
+// Copyright (c) 2026 Petr Balvín <opensource@petrbalvin.org> (https://petrbalvin.org)
+// SPDX-License-Identifier: BSD-3-Clause
+
+package verify
+
+import (
+	"testing"
+)
+
+func TestExtractSignatures(t *testing.T) {
+	src := `// func add(a int64, b int64) int64
+TEXT ·add(SB), NOSPLIT, $0-24
+	RET
+
+// func wideCopy(dst []byte, src []byte)
+TEXT ·wideCopy(SB), NOSPLIT, $0-48
+	RET
+`
+	sigs := ExtractSignatures(src)
+	if len(sigs) != 2 {
+		t.Fatalf("expected 2 signatures, got %d: %v", len(sigs), sigs)
+	}
+	add, ok := sigs["add"]
+	if !ok {
+		t.Fatal("add not found")
+	}
+	if len(add.params) != 2 {
+		t.Errorf("add params: got %d, want 2", len(add.params))
+	}
+	wc, ok := sigs["wideCopy"]
+	if !ok {
+		t.Fatal("wideCopy not found")
+	}
+	if len(wc.params) != 2 {
+		t.Errorf("wideCopy params: got %d, want 2", len(wc.params))
+	}
+	if wc.params[0].typ != "[]byte" {
+		t.Errorf("wideCopy param[0].typ = %q, want []byte", wc.params[0].typ)
+	}
+}
+
+func TestFuzzWideCopy(t *testing.T) {
+	k := loadBasic(t)
+
+	gt, err := GroundTruth("../testdata/verify/basic_amd64.s")
+	if err != nil {
+		t.Fatalf("GroundTruth: %v", err)
+	}
+	goCode, ok := gt["wideCopy"]
+	if !ok {
+		t.Skip("wideCopy not in ground truth")
+	}
+
+	sig := funcSig{
+		name: "wideCopy",
+		params: []param{
+			{name: "dst", typ: "[]byte"},
+			{name: "src", typ: "[]byte"},
+		},
+	}
+
+	res := k.FuzzFunc("wideCopy", sig, goCode, 200, 42)
+	if !res.OK() {
+		t.Errorf("wideCopy fuzz: %s", res)
+	}
+}
+
+func TestParseFuncSig(t *testing.T) {
+	tests := []struct {
+		comment string
+		name    string
+		nParams int
+	}{
+		{"// func add(a int64, b int64) int64", "add", 2},
+		{"// func wideCopy(dst []byte, src []byte)", "wideCopy", 2},
+		{"// func analyzeO1RangeAVX2(swin []int32, dstP []uint32, hist *[32]uint16) (partSum uint64, overflow bool)", "analyzeO1RangeAVX2", 3},
+		{"// not a func", "", 0},
+	}
+	for _, tt := range tests {
+		sig, ok := parseFuncSig(tt.comment)
+		if tt.name == "" {
+			if ok {
+				t.Errorf("parseFuncSig(%q): expected not ok", tt.comment)
+			}
+			continue
+		}
+		if !ok {
+			t.Errorf("parseFuncSig(%q): expected ok", tt.comment)
+			continue
+		}
+		if sig.name != tt.name {
+			t.Errorf("parseFuncSig(%q).name = %q, want %q", tt.comment, sig.name, tt.name)
+		}
+		if len(sig.params) != tt.nParams {
+			t.Errorf("parseFuncSig(%q): %d params, want %d", tt.comment, len(sig.params), tt.nParams)
+		}
+	}
+}