test: Update fuzz tests to use the built-in infrastructure

Go 1.18 supports fuzzing natively, so this patch migrates our fuzzing
tests to make use of it.

internal/auth/auth_test.go

@@ -285,3 +285,10 @@ func TestReload(t *testing.T) {
 		t.Errorf("unexpected error reloading wrapped backend: %v", err)
 	}
 }
+
+// Fuzz testing for the response decoder, which handles user-provided data.
+func FuzzDecodeResponse(f *testing.F) {
+	f.Fuzz(func(t *testing.T, response string) {
+		DecodeResponse(response)
+	})
+}

internal/auth/fuzz.go

@@ -1,17 +0,0 @@
-// Fuzz testing for package aliases.
-
-//go:build gofuzz
-// +build gofuzz
-
-package auth
-
-func Fuzz(data []byte) int {
-	//	user, domain, passwd, err := DecodeResponse(string(data))
-	interesting := 0
-	_, _, _, err := DecodeResponse(string(data))
-	if err == nil {
-		interesting = 1
-	}
-
-	return interesting
-}

internal/auth/testdata/fuzz/FuzzDecodeResponse/0274b170c6fe2654ca5418a914b804e9c7cc5d8e5c2a7c5fcf5c29540ec5ae52

@@ -0,0 +1,2 @@
+go test fuzz v1
+string("@\xed\x88̥̥̥̥̥̥̄̈́̈́̈́̈́̈́̈́̈́̈́ͥ̈́̈́ͥ̓\x00\x00")

internal/auth/testdata/fuzz/FuzzDecodeResponse/24d35771ef1fe0645d90b061e13a777faea328736483ec2833b63950d26b5399

@@ -0,0 +1,2 @@
+go test fuzz v1
+string("AHVAZABwYXNz")

internal/auth/testdata/fuzz/FuzzDecodeResponse/2e5d0b26626f2d2dd6fb423e1e1cc432277ae9877c622fe6ca067e247bc11c9d

@@ -0,0 +1,2 @@
+go test fuzz v1
+string("dUBkAHVAZABwYXNz")

internal/auth/testdata/fuzz/FuzzDecodeResponse/2ef1aee5347414c139270ebb6ea63d2223a8c0c7c8ec30a2ca7152f4c18f1c74

@@ -0,0 +1,2 @@
+go test fuzz v1
+string("\xeb̥̥̥̥̥̥̥̈́ͥ̈́̈́̈́̈́̈́̈́̈́̈́̈́ͥ̓@\x00\x00")

internal/auth/testdata/fuzz/FuzzDecodeResponse/4b9259040da90f06aa2b593ee20fdffefeda813c59430050f15965bd9471235e

@@ -0,0 +1,2 @@
+go test fuzz v1
+string("this is not base64 encoded")

internal/auth/testdata/fuzz/FuzzDecodeResponse/6c2c0b4f81a675d91d1291bfdcddb7c9d43cf6264dd7763cfed31a3946854e27

@@ -0,0 +1,2 @@
+go test fuzz v1
+string("\xeb̥̥̥̥̥̥ͯ̈́̈́̈́̈́̈́ͯ̈́̈́̈́̈́̈́̈́@\x00\x00")

internal/auth/testdata/fuzz/FuzzDecodeResponse/6e05782952b68c7ccd94160ad6ea45e7f766397850b08e78f89407a94350825c

@@ -0,0 +1,2 @@
+go test fuzz v1
+string("\xeb̥̥̥̥̥̥̈́̈́̈́̈́̈́ͯ̈́̈́̈́̈́̈́̈́̈́@\x00\x00")

internal/auth/testdata/fuzz/FuzzDecodeResponse/c2ae184876dd0fe9acfc8a5e2f2174a968b889b01e0f5c9a61fa27d7361f0091

@@ -0,0 +1,2 @@
+go test fuzz v1
+string("dUBkAABwYXNz")

internal/auth/testdata/fuzz/FuzzDecodeResponse/d9aa9c617d1f5b3021aca758b9d896d136e3b16ed53233d02abffd02aa73ffa4

@@ -0,0 +1,2 @@
+go test fuzz v1
+string("w7FhY2FAw7FlcXVlAABjbGF2YXLDqQ==")

internal/auth/testdata/fuzz/FuzzDecodeResponse/de05c7993312bab83e8114e9d9ced331c49822dc55c1a353f1cc9718a28226e7

@@ -0,0 +1,2 @@
+go test fuzz v1
+string("dUBkAABwYXNz/w==")

internal/auth/testdata/fuzz/corpus/t-001

@@ -1 +0,0 @@
-dUBkAHVAZABwYXNz

internal/auth/testdata/fuzz/corpus/t-002

@@ -1 +0,0 @@
-dUBkAABwYXNz

internal/auth/testdata/fuzz/corpus/t-003

@@ -1 +0,0 @@
-AHVAZABwYXNz

internal/auth/testdata/fuzz/corpus/t-004

@@ -1 +0,0 @@
-dUBkAABwYXNz/w==

internal/auth/testdata/fuzz/corpus/t-005

@@ -1 +0,0 @@
-w7FhY2FAw7FlcXVlAABjbGF2YXLDqQ==

internal/auth/testdata/fuzz/corpus/t-006

@@ -1 +0,0 @@
-this is not base64 encoded