Do not build decode table for base85 until it is actually needed

Also make the tests actual tests

tools/utils/base85/base85_test.go

@@ -1,60 +1,54 @@
 package base85
 
 import (
-	"testing"
 	"fmt"
+	"testing"
+
+	"github.com/google/go-cmp/cmp"
 )
 
-func TestChunked (t *testing.T) {
-	a := []byte("M")
-	fmt.Printf("a %#v\n", a)
-	b := make([]byte, EncodedLen(len(a)))
-	encodeChunk(b, a)
-	fmt.Printf("b %#v\n", b)
-	c := make([]byte, DecodedLen(len(b)))
-	decodeChunk(c, b)
-	fmt.Printf("c %#v\n", c)
+var _ = fmt.Print
 
-	a = []byte("Ma")
-	fmt.Printf("a %#v\n", a)
-	b = make([]byte, EncodedLen(len(a)))
-	encodeChunk(b, a)
-	fmt.Printf("b %#v\n", b)
-	c = make([]byte, DecodedLen(len(b)))
-	decodeChunk(c, b)
-	fmt.Printf("c %#v\n", c)
-
-	a = []byte("Man")
-	fmt.Printf("a %#v\n", a)
-	b = make([]byte, EncodedLen(len(a)))
-	encodeChunk(b, a)
-	fmt.Printf("b %#v\n", b)
-	c = make([]byte, DecodedLen(len(b)))
-	decodeChunk(c, b)
-	fmt.Printf("c %#v\n", c)
-
-	a = []byte("Man ")
-	fmt.Printf("a %#v\n", a)
-	b = make([]byte, EncodedLen(len(a)))
-	encodeChunk(b, a)
-	fmt.Printf("b %#v\n", b)
-	c = make([]byte, DecodedLen(len(b)))
-	decodeChunk(c, b)
-	fmt.Printf("c %#v\n", c)
-
-	a = []byte("Manual")
-	fmt.Printf("a %#v\n", a)
-	b = make([]byte, EncodedLen(len(a)))
-	n := Encode(b, a)
-	fmt.Printf("b %#v %d\n", b, n)
-	c = make([]byte, DecodedLen(len(b)))
-	n, _ = Decode(c, b)
-	fmt.Printf("c %#v %d\n", c, n)
-
-	a = []byte("Manual")
-	fmt.Printf("a %s\n", a)
-	sb := EncodeToString(a) + "\""
-	fmt.Printf("b %#v\n", sb)
-	sc, err := DecodeString(sb)
-	fmt.Printf("c %s %s\n", sc, err)
+type pair struct {
+	src, encoded string
+}
+
+func TestBase85(t *testing.T) {
+	dst, dst2 := [8]byte{}, [8]byte{}
+	decode := decoder_array()
+	var el int
+	for _, x := range []string{"M", "Ma", "Man", "Man "} {
+		a := []byte(x)
+		if el = encodeChunk(dst[:], a); el != EncodedLen(len(a)) {
+			t.Fatalf("Encoded len for %#v wrong: %d != %d", x, el, EncodedLen(len(a)))
+		}
+		encoded := dst[:el]
+		dl, bad_idx := decodeChunk(&decode, dst2[:], encoded)
+		if bad_idx != 0 {
+			t.Fatalf("Decode for %#v returned bad data at: %d (%#v)", x, bad_idx, encoded)
+		}
+		if dl != DecodedLen(len(encoded)) {
+			t.Fatalf("Decoded len for %#v wrong: %d != %d", x, dl, DecodedLen(len(a)))
+		}
+		decoded := string(dst2[:dl])
+		if diff := cmp.Diff(x, decoded); diff != "" {
+			t.Fatalf("Roundtrip failed for %#v: %s", x, diff)
+		}
+	}
+	for _, p := range []pair{
+		{"M", "O#"},
+		{"Manual", "O<`_zVQc"},
+	} {
+		q := EncodeToString([]byte(p.src))
+		if diff := cmp.Diff(p.encoded, q); diff != "" {
+			t.Fatalf("Incorrect encoding of: %#v\n%s", p.src, diff)
+		}
+		sc, err := DecodeString(q)
+		if err != nil {
+			t.Fatalf("Failed to decode %#v with error: %s", p.src, err)
+		}
+		if diff := cmp.Diff(p.src, string(sc)); diff != "" {
+			t.Fatalf("Failed to roundtrip %#v\n%s", p.src, diff)
+		}
+	}
 }