From bd21e377c8d0fe6470201b3a9c707a225f19cbd9 Mon Sep 17 00:00:00 2001
From: DualFroz <me@dualfroz.com>
Date: Sat, 12 Sep 2026 16:46:35 +0200
Subject: [PATCH] test: cover slabTest

---
 src/slabTest.c | 154 +++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 154 insertions(+)
 create mode 100644 src/slabTest.c

diff --git a/src/slabTest.c b/src/slabTest.c
new file mode 100644
index 0000000..5036387
--- /dev/null
+++ b/src/slabTest.c
@@ -0,0 +1,154 @@
+#include "ktest.h"
+#include "slab.h"
+#include "pmm.h"
+#include "string.h"
+#include "heap.h"
+
+KTEST(slabInitRejectsOversizedObject)
+{
+    KmemCache cache;
+    KT_FALSE(t, kmemCacheInit(&cache, "toobig", frameSize));
+    KT_EQ(t, kmemCacheCapacity(&cache), 0);
+    KT_NULL(t, kmemCacheAlloc(&cache));
+}
+
+KTEST(slabAllocDistinctNonOverlapping)
+{
+    KmemCache cache;
+    KT_TRUE(t, kmemCacheInit(&cache, "small32", 32));
+    KT_GT(t, kmemCacheObjsPerSlab(&cache), 0);
+    KT_EQ(t, kmemCacheCapacity(&cache), 0);   /* nothing grown yet */
+
+    void* a = kmemCacheAlloc(&cache);
+    void* b = kmemCacheAlloc(&cache);
+    void* c = kmemCacheAlloc(&cache);
+    KT_NOTNULL(t, a);
+    KT_NOTNULL(t, b);
+    KT_NOTNULL(t, c);
+    KT_NE(t, a, b);
+    KT_NE(t, b, c);
+    KT_NE(t, a, c);
+    KT_EQ(t, kmemCacheUsed(&cache), 3);
+
+    /* write a distinct pattern into each object and check none of them
+       stomped on a neighbor */
+    memset(a, 0xAA, 32);
+    memset(b, 0xBB, 32);
+    memset(c, 0xCC, 32);
+    uint8 probe[32];
+    memset(probe, 0xAA, 32);
+    KT_EQ(t, memcmp(a, probe, 32), 0);
+    memset(probe, 0xBB, 32);
+    KT_EQ(t, memcmp(b, probe, 32), 0);
+    memset(probe, 0xCC, 32);
+    KT_EQ(t, memcmp(c, probe, 32), 0);
+
+    kmemCacheFree(&cache, a);
+    kmemCacheFree(&cache, b);
+    kmemCacheFree(&cache, c);
+    KT_EQ(t, kmemCacheUsed(&cache), 0);
+
+    kmemCacheDestroy(&cache);
+}
+
+KTEST(slabFreeReusesLifo)
+{
+    KmemCache cache;
+    kmemCacheInit(&cache, "reuse", 16);
+
+    void* a = kmemCacheAlloc(&cache);
+    kmemCacheFree(&cache, a);
+    void* b = kmemCacheAlloc(&cache);
+    KT_EQP(t, a, b);   /* single-slot free list, must come back the same */
+
+    kmemCacheFree(&cache, b);
+    kmemCacheDestroy(&cache);
+}
+
+KTEST(slabGrowsAcrossMultipleSlabs)
+{
+    KmemCache cache;
+    kmemCacheInit(&cache, "grow64", 64);
+    usize perSlab = kmemCacheObjsPerSlab(&cache);
+    KT_GT(t, perSlab, 0);
+
+    uint64 framesBefore = pmmFreeFrames();
+
+    /* fill exactly the first slab */
+    void* first = nullptr;
+    for (usize i = 0; i < perSlab; i++) {
+        void* p = kmemCacheAlloc(&cache);
+        KT_NOTNULL(t, p);
+        if (i == 0)
+            first = p;
+    }
+    KT_EQ(t, kmemCacheSlabCount(&cache), 1);
+    KT_EQ(t, kmemCacheUsed(&cache), perSlab);
+
+    /* one more forces a second slab (a second frame from pmm) */
+    void* overflow = kmemCacheAlloc(&cache);
+    KT_NOTNULL(t, overflow);
+    KT_EQ(t, kmemCacheSlabCount(&cache), 2);
+    KT_EQ(t, kmemCacheCapacity(&cache), perSlab * 2);
+    KT_EQ(t, pmmFreeFrames(), framesBefore - 2);
+    KT_NE(t, overflow, first);
+
+    kmemCacheDestroy(&cache);
+    /* destroying the cache must return every frame it ever grew into */
+    KT_EQ(t, pmmFreeFrames(), framesBefore);
+}
+
+#define slabStressCount 800
+
+KTEST(slabStressAllocFreePattern)
+{
+    KmemCache cache;
+    kmemCacheInit(&cache, "stress", 40);
+
+    void** slots = (void**)kmalloc(sizeof(void*) * slabStressCount);
+    KT_NOTNULL(t, slots);
+    if (!slots) {
+        kmemCacheDestroy(&cache);
+        return;
+    }
+
+    for (int i = 0; i < slabStressCount; i++) {
+        slots[i] = kmemCacheAlloc(&cache);
+        KT_NOTNULL(t, slots[i]);
+        if (slots[i])
+            *(int32*)slots[i] = i;
+    }
+    KT_EQ(t, kmemCacheUsed(&cache), slabStressCount);
+
+    /* every slot still holds the value we stamped, none aliased */
+    for (int i = 0; i < slabStressCount; i++) {
+        if (slots[i])
+            KT_EQ(t, *(int32*)slots[i], i);
+    }
+
+    /* free every third object, then re-allocate that many and confirm the
+       cache handed back exactly that many reclaimed slots (no capacity
+       growth needed to satisfy them) */
+    usize freedCount = 0;
+    for (int i = 0; i < slabStressCount; i += 3) {
+        kmemCacheFree(&cache, slots[i]);
+        slots[i] = nullptr;
+        freedCount++;
+    }
+    KT_EQ(t, kmemCacheUsed(&cache), slabStressCount - freedCount);
+
+    usize capacityBeforeRefill = kmemCacheCapacity(&cache);
+    for (int i = 0; i < slabStressCount; i += 3) {
+        slots[i] = kmemCacheAlloc(&cache);
+        KT_NOTNULL(t, slots[i]);
+    }
+    KT_EQ(t, kmemCacheCapacity(&cache), capacityBeforeRefill);
+    KT_EQ(t, kmemCacheUsed(&cache), slabStressCount);
+
+    for (int i = 0; i < slabStressCount; i++)
+        kmemCacheFree(&cache, slots[i]);
+    KT_EQ(t, kmemCacheUsed(&cache), 0);
+
+    kfree(slots);
+    kmemCacheDestroy(&cache);
+}