test: add failing tests for cache_max_bytes config and cache eviction
Red phase for #51: covers strict cache_max_bytes parsing (invalid explicit values abort naming key and value), the computed default of max(75% of free space, 500 MiB) via an injectable free-space probe, explicit-value-no-floor, zero-disables-cache, size accounting over source blobs and variants, LRU eviction under the limit, the multi-referenced blob case, write-pressure and periodic eviction triggers, and startup reconciliation. Minimal API skeletons keep the tree compiling and lint-clean; only the new tests fail.
This commit is contained in:
271
internal/config/cache_max_bytes_test.go
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271
internal/config/cache_max_bytes_test.go
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package config
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import (
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"errors"
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"io"
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"log/slog"
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"os"
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"path/filepath"
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"strings"
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"testing"
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)
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// discardLogger returns a logger that swallows all output, for tests
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// that exercise code paths which log.
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func discardLogger() *slog.Logger {
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return slog.New(slog.NewTextHandler(io.Discard, nil))
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}
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// TestCacheMaxBytesExplicitValueUsedWithoutFloor verifies that an
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// explicitly configured cache_max_bytes value is used exactly as
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// given: the 500 MiB floor applies only to the computed default, never
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// to explicit values.
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func TestCacheMaxBytesExplicitValueUsedWithoutFloor(t *testing.T) {
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yamlContent := "signing_key: " + validTestSigningKey + "\ncache_max_bytes: 1024\n"
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c, err := configFromYAML(t, yamlContent)
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if err != nil {
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t.Fatalf("explicit cache_max_bytes must be accepted, got error: %v", err)
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}
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if c.CacheMaxBytes != 1024 {
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t.Errorf("CacheMaxBytes = %d, want 1024 (no floor for explicit values)",
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c.CacheMaxBytes)
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}
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}
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// TestCacheMaxBytesZeroIsValidAndDisablesCache verifies that an
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// explicit zero is a valid value (it disables the disk cache), not an
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// error.
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func TestCacheMaxBytesZeroIsValidAndDisablesCache(t *testing.T) {
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yamlContent := "signing_key: " + validTestSigningKey + "\ncache_max_bytes: 0\n"
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c, err := configFromYAML(t, yamlContent)
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if err != nil {
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t.Fatalf("cache_max_bytes: 0 must be accepted, got error: %v", err)
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}
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if c.CacheMaxBytes != 0 {
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t.Errorf("CacheMaxBytes = %d, want 0", c.CacheMaxBytes)
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}
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}
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// TestCacheMaxBytesLargeExplicitValueParses verifies that values above
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// 32-bit range parse correctly (the field is an int64 byte count).
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func TestCacheMaxBytesLargeExplicitValueParses(t *testing.T) {
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yamlContent := "signing_key: " + validTestSigningKey + "\ncache_max_bytes: 10737418240\n"
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c, err := configFromYAML(t, yamlContent)
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if err != nil {
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t.Fatalf("large cache_max_bytes must be accepted, got error: %v", err)
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}
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if c.CacheMaxBytes != 10737418240 {
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t.Errorf("CacheMaxBytes = %d, want 10737418240", c.CacheMaxBytes)
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}
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}
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// TestCacheMaxBytesInvalidValuesAbortStartup verifies that a SET but
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// invalid cache_max_bytes value aborts startup naming the key and the
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// offending value, per the no-silent-fallback rule: defaults apply
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// only to omitted keys.
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func TestCacheMaxBytesInvalidValuesAbortStartup(t *testing.T) {
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signingKeyLine := "signing_key: " + validTestSigningKey + "\n"
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cases := []struct {
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name string
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yaml string
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// wantErrSubstrings must all appear in the error message.
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wantErrSubstrings []string
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}{
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{
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name: "negative",
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yaml: signingKeyLine + "cache_max_bytes: -1024\n",
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wantErrSubstrings: []string{"cache_max_bytes", "-1024"},
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},
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{
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name: "float",
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yaml: signingKeyLine + "cache_max_bytes: 3.5\n",
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wantErrSubstrings: []string{"cache_max_bytes", "3.5"},
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},
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{
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name: "non-numeric string",
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yaml: signingKeyLine + "cache_max_bytes: banana\n",
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wantErrSubstrings: []string{"cache_max_bytes", "banana"},
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},
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{
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name: "explicit null",
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yaml: signingKeyLine + "cache_max_bytes: null\n",
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wantErrSubstrings: []string{"cache_max_bytes", "null"},
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},
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{
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name: "bare key no value",
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yaml: signingKeyLine + "cache_max_bytes:\n",
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wantErrSubstrings: []string{"cache_max_bytes", "null"},
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},
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{
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name: "boolean",
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yaml: signingKeyLine + "cache_max_bytes: true\n",
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wantErrSubstrings: []string{"cache_max_bytes", "true"},
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},
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{
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name: "list",
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yaml: signingKeyLine + "cache_max_bytes:\n - 1\n",
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wantErrSubstrings: []string{"cache_max_bytes"},
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},
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}
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for _, tc := range cases {
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t.Run(tc.name, func(t *testing.T) {
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c, err := configFromYAML(t, tc.yaml)
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if err == nil {
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t.Fatalf("config with %s cache_max_bytes must abort startup, got config: %+v",
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tc.name, c)
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}
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t.Logf("got expected error: %v", err)
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for _, want := range tc.wantErrSubstrings {
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if !strings.Contains(err.Error(), want) {
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t.Errorf("error %q does not mention %q", err.Error(), want)
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}
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}
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})
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}
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}
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// TestComputeDefaultCacheMaxBytesUses75PercentOfFreeSpace verifies the
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// computed default is 75% of the probed free space when that exceeds
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// the floor.
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func TestComputeDefaultCacheMaxBytesUses75PercentOfFreeSpace(t *testing.T) {
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// 4 GiB free -> 3 GiB default.
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probe := func(string) (uint64, error) { return 4294967296, nil }
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got, err := ComputeDefaultCacheMaxBytes(t.TempDir(), probe)
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if err != nil {
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t.Fatalf("ComputeDefaultCacheMaxBytes returned error: %v", err)
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}
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if got != 3221225472 {
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t.Errorf("ComputeDefaultCacheMaxBytes = %d, want 3221225472 (75%% of 4 GiB)", got)
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}
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}
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// TestComputeDefaultCacheMaxBytesAppliesFloorToComputedDefault
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// verifies that when 75% of free space is below 500 MiB, the computed
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// default is floored at DefaultCacheMaxBytesFloor.
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func TestComputeDefaultCacheMaxBytesAppliesFloorToComputedDefault(t *testing.T) {
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cases := []struct {
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name string
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freeBytes uint64
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}{
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{name: "100 MiB free", freeBytes: 104857600},
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{name: "zero free", freeBytes: 0},
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{name: "just below floor threshold", freeBytes: 699050665},
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}
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for _, tc := range cases {
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t.Run(tc.name, func(t *testing.T) {
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probe := func(string) (uint64, error) { return tc.freeBytes, nil }
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got, err := ComputeDefaultCacheMaxBytes(t.TempDir(), probe)
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if err != nil {
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t.Fatalf("ComputeDefaultCacheMaxBytes returned error: %v", err)
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}
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if got != DefaultCacheMaxBytesFloor {
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t.Errorf("ComputeDefaultCacheMaxBytes = %d, want floor %d",
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got, DefaultCacheMaxBytesFloor)
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}
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})
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}
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}
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// TestComputeDefaultCacheMaxBytesPropagatesProbeError verifies that a
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// failing free-space probe produces an error naming the config key,
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// instead of a silently wrong default.
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func TestComputeDefaultCacheMaxBytesPropagatesProbeError(t *testing.T) {
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probe := func(string) (uint64, error) { return 0, errors.New("statfs failed") }
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_, err := ComputeDefaultCacheMaxBytes(t.TempDir(), probe)
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if err == nil {
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t.Fatal("probe failure must produce an error, got nil")
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}
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t.Logf("got expected error: %v", err)
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if !strings.Contains(err.Error(), "cache_max_bytes") {
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t.Errorf("error %q does not name the config key cache_max_bytes", err.Error())
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}
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}
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// TestResolveCacheMaxBytesComputesDefaultWhenOmitted verifies that an
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// omitted cache_max_bytes key resolves to the computed default, that
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// the probe is pointed at <state_dir>/cache/ (which must be created
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// first so statfs measures the right filesystem), and that the result
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// lands on the Config.
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func TestResolveCacheMaxBytesComputesDefaultWhenOmitted(t *testing.T) {
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c, err := configFromYAML(t, "signing_key: "+validTestSigningKey+"\n")
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if err != nil {
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t.Fatalf("minimal config should be valid, got error: %v", err)
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}
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c.StateDir = t.TempDir()
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wantCacheDir := filepath.Join(c.StateDir, "cache")
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var probedPath string
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// 4 GiB free -> 3 GiB default.
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probe := func(path string) (uint64, error) {
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probedPath = path
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return 4294967296, nil
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}
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if err := c.resolveCacheMaxBytes(discardLogger(), probe); err != nil {
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t.Fatalf("resolveCacheMaxBytes returned error: %v", err)
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}
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if c.CacheMaxBytes != 3221225472 {
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t.Errorf("CacheMaxBytes = %d, want computed default 3221225472", c.CacheMaxBytes)
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}
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if probedPath != wantCacheDir {
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t.Errorf("free space probed at %q, want cache directory %q", probedPath, wantCacheDir)
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}
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info, err := os.Stat(wantCacheDir)
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if err != nil || !info.IsDir() {
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t.Errorf("cache directory %q was not created before probing: info=%v err=%v",
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wantCacheDir, info, err)
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}
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}
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// TestResolveCacheMaxBytesDoesNotOverrideExplicitValue verifies that
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// an explicitly configured value survives resolution untouched and
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// that the free-space probe is never consulted for it.
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func TestResolveCacheMaxBytesDoesNotOverrideExplicitValue(t *testing.T) {
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yamlContent := "signing_key: " + validTestSigningKey + "\ncache_max_bytes: 1024\n"
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c, err := configFromYAML(t, yamlContent)
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if err != nil {
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t.Fatalf("explicit cache_max_bytes must be accepted, got error: %v", err)
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}
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c.StateDir = t.TempDir()
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probe := func(string) (uint64, error) {
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t.Error("free-space probe must not be consulted for explicit values")
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return 0, errors.New("probe must not be called")
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}
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if err := c.resolveCacheMaxBytes(discardLogger(), probe); err != nil {
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t.Fatalf("resolveCacheMaxBytes returned error: %v", err)
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}
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if c.CacheMaxBytes != 1024 {
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t.Errorf("CacheMaxBytes = %d, want explicit 1024 (no floor, no recompute)",
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c.CacheMaxBytes)
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}
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}
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