std/hash: add generic tests for idempotency/iterative api

7 files changed, 61 insertions, 48 deletions

diff --git a/lib/std/hash/adler.zig b/lib/std/hash/adler.zig
index 200dc9aafe..52f7b2691a 100644
--- a/lib/std/hash/adler.zig
+++ b/lib/std/hash/adler.zig
@@ -3,7 +3,7 @@
 // https://tools.ietf.org/html/rfc1950#section-9
 // https://github.com/madler/zlib/blob/master/adler32.c
 
-const std = @import("../std.zig");
+const std = @import("std");
 const testing = std.testing;
 
 pub const Adler32 = struct {
@@ -126,3 +126,9 @@ test "adler32 very long with variation" {
 
     try testing.expectEqual(@as(u32, 0x5af38d6e), std.hash.Adler32.hash(long[0..]));
 }
+
+const verify = @import("verify.zig");
+
+test "adler32 iterative" {
+    try verify.iterativeApi(Adler32);
+}
diff --git a/lib/std/hash/crc.zig b/lib/std/hash/crc.zig
index 9a5936874d..cbd3c75d4d 100644
--- a/lib/std/hash/crc.zig
+++ b/lib/std/hash/crc.zig
@@ -5,7 +5,7 @@
 // - Crc32SmallWithPoly uses only 64 bytes of memory but is slower. Be aware that this is
 //   still moderately fast just slow relative to the slicing approach.
 
-const std = @import("../std.zig");
+const std = @import("std");
 const builtin = @import("builtin");
 const debug = std.debug;
 const testing = std.testing;
@@ -194,6 +194,8 @@ pub fn Crc32WithPoly(comptime poly: Polynomial) type {
     };
 }
 
+const verify = @import("verify.zig");
+
 test "crc32 ieee" {
     const Crc32Ieee = Crc32WithPoly(.IEEE);
 
@@ -210,6 +212,10 @@ test "crc32 castagnoli" {
     try testing.expect(Crc32Castagnoli.hash("abc") == 0x364b3fb7);
 }
 
+test "crc32 iterative" {
+    try verify.iterativeApi(Crc32WithPoly(.IEEE));
+}
+
 // half-byte lookup table implementation.
 pub fn Crc32SmallWithPoly(comptime poly: Polynomial) type {
     return struct {
@@ -258,6 +264,10 @@ pub fn Crc32SmallWithPoly(comptime poly: Polynomial) type {
     };
 }
 
+test "small crc32 iterative" {
+    try verify.iterativeApi(Crc32SmallWithPoly(.IEEE));
+}
+
 test "small crc32 ieee" {
     const Crc32Ieee = Crc32SmallWithPoly(.IEEE);
 
diff --git a/lib/std/hash/crc/catalog_test.zig b/lib/std/hash/crc/catalog_test.zig
index b9bf21fc99..ab89745ca8 100644
--- a/lib/std/hash/crc/catalog_test.zig
+++ b/lib/std/hash/crc/catalog_test.zig
@@ -1,6 +1,6 @@
 //! This file is auto-generated by tools/update_crc_catalog.zig.
 
-const std = @import("../../std.zig");
+const std = @import("std");
 const testing = std.testing;
 const catalog = @import("catalog.zig");
 
diff --git a/lib/std/hash/fnv.zig b/lib/std/hash/fnv.zig
index c95f19c04e..01469bff8a 100644
--- a/lib/std/hash/fnv.zig
+++ b/lib/std/hash/fnv.zig
@@ -40,19 +40,24 @@ fn Fnv1a(comptime T: type, comptime prime: T, comptime offset: T) type {
     };
 }
 
+const verify = @import("verify.zig");
+
 test "fnv1a-32" {
     try testing.expect(Fnv1a_32.hash("") == 0x811c9dc5);
     try testing.expect(Fnv1a_32.hash("a") == 0xe40c292c);
     try testing.expect(Fnv1a_32.hash("foobar") == 0xbf9cf968);
+    try verify.iterativeApi(Fnv1a_32);
 }
 
 test "fnv1a-64" {
     try testing.expect(Fnv1a_64.hash("") == 0xcbf29ce484222325);
     try testing.expect(Fnv1a_64.hash("a") == 0xaf63dc4c8601ec8c);
     try testing.expect(Fnv1a_64.hash("foobar") == 0x85944171f73967e8);
+    try verify.iterativeApi(Fnv1a_64);
 }
 
 test "fnv1a-128" {
     try testing.expect(Fnv1a_128.hash("") == 0x6c62272e07bb014262b821756295c58d);
     try testing.expect(Fnv1a_128.hash("a") == 0xd228cb696f1a8caf78912b704e4a8964);
+    try verify.iterativeApi(Fnv1a_128);
 }
diff --git a/lib/std/hash/verify.zig b/lib/std/hash/verify.zig
index bfc6a1f22c..5d853fee28 100644
--- a/lib/std/hash/verify.zig
+++ b/lib/std/hash/verify.zig
@@ -13,6 +13,15 @@ fn hashMaybeSeed(comptime hash_fn: anytype, seed: anytype, buf: []const u8) @typ
     }
 }
 
+fn initMaybeSeed(comptime Hash: anytype, seed: anytype) Hash {
+    const HashFn = @typeInfo(@TypeOf(Hash.init)).Fn;
+    if (HashFn.params.len == 1) {
+        return Hash.init(@intCast(seed));
+    } else {
+        return Hash.init();
+    }
+}
+
 // Returns a verification code, the same as user by SMHasher.
 //
 // Hash keys of the form {0}, {0,1}, {0,1,2}... up to N=255, using 256-N as seed.
@@ -33,3 +42,21 @@ pub fn smhasher(comptime hash_fn: anytype) u32 {
 
     return @truncate(hashMaybeSeed(hash_fn, 0, buf_all[0..]));
 }
+
+pub fn iterativeApi(comptime Hash: anytype) !void {
+    // Sum(1..32) = 528
+    var buf: [528]u8 = [_]u8{0} ** 528;
+    var len: usize = 0;
+    const seed = 0;
+
+    var hasher = initMaybeSeed(Hash, seed);
+    for (1..32) |i| {
+        const r = hashMaybeSeed(Hash.hash, seed, buf[0 .. len + i]);
+        hasher.update(buf[len..][0..i]);
+        const f1 = hasher.final();
+        const f2 = hasher.final();
+        if (f1 != f2) return error.IterativeHashWasNotIdempotent;
+        if (f1 != r) return error.IterativeHashDidNotMatchDirect;
+        len += i;
+    }
+}
diff --git a/lib/std/hash/wyhash.zig b/lib/std/hash/wyhash.zig
index 741b117f5d..6ceaba696a 100644
--- a/lib/std/hash/wyhash.zig
+++ b/lib/std/hash/wyhash.zig
@@ -234,51 +234,8 @@ test "smhasher" {
     try expectEqual(verify.smhasher(Wyhash.hash), 0xBD5E840C);
 }
 
-test "test vectors streaming" {
-    const step = 5;
-
-    for (vectors) |e| {
-        var wh = Wyhash.init(e.seed);
-        var i: usize = 0;
-        while (i < e.input.len) : (i += step) {
-            const len = if (i + step > e.input.len) e.input.len - i else step;
-            wh.update(e.input[i..][0..len]);
-        }
-        try expectEqual(e.expected, wh.final());
-    }
-}
-
-test "test ensure idempotent final call" {
-    const e: TestVector = .{ .seed = 6, .expected = 0xc39cab13b115aad3, .input = "12345678901234567890123456789012345678901234567890123456789012345678901234567890" };
-    var wh = Wyhash.init(e.seed);
-    wh.update(e.input);
-
-    for (0..10) |_| {
-        try expectEqual(e.expected, wh.final());
-    }
-}
-
-test "iterative non-divisible update" {
-    var buf: [8192]u8 = undefined;
-    for (&buf, 0..) |*e, i| {
-        e.* = @as(u8, @truncate(i));
-    }
-
-    const seed = 0x128dad08f;
-
-    var end: usize = 32;
-    while (end < buf.len) : (end += 32) {
-        const non_iterative_hash = Wyhash.hash(seed, buf[0..end]);
-
-        var wy = Wyhash.init(seed);
-        var i: usize = 0;
-        while (i < end) : (i += 33) {
-            wy.update(buf[i..@min(i + 33, end)]);
-        }
-        const iterative_hash = wy.final();
-
-        try std.testing.expectEqual(iterative_hash, non_iterative_hash);
-    }
+test "iterative api" {
+    try verify.iterativeApi(Wyhash);
 }
 
 test "iterative maintains last sixteen" {
diff --git a/lib/std/hash/xxhash.zig b/lib/std/hash/xxhash.zig
index 6b6208b854..f267f72e6a 100644
--- a/lib/std/hash/xxhash.zig
+++ b/lib/std/hash/xxhash.zig
@@ -461,6 +461,10 @@ test "xxhash64" {
     try expectEqual(verify.smhasher(H.hash), 0x024B7CF4);
 }
 
+test "xxhash64 iterative api" {
+    try verify.iterativeApi(XxHash64);
+}
+
 test "xxhash32" {
     const H = XxHash32;
 
@@ -474,3 +478,7 @@ test "xxhash32" {
 
     try expectEqual(verify.smhasher(H.hash), 0xBA88B743);
 }
+
+test "xxhash32 iterative api" {
+    try verify.iterativeApi(XxHash32);
+}