cache_opts: address PR comments

settings.go

@@ -93,7 +93,7 @@ func EnableCaching(enabled bool) error {
 	}
 }
 
-func GetCachedMemory() (int, int, error) {
+func GetCachedMemory() (current int, allowed int, err error) {
 	return getSizetSizet(C.GIT_OPT_GET_CACHED_MEMORY)
 }
 
@@ -130,8 +130,7 @@ func getSizetSizet(opt C.int) (int, int, error) {
 	runtime.LockOSThread()
 	defer runtime.UnlockOSThread()
 
-	var val1 C.size_t
-	var val2 C.size_t
+	var val1, val2 C.size_t
 	err := C._go_git_opts_get_size_t_size_t(opt, &val1, &val2)
 	if err < 0 {
 		return 0, 0, MakeGitError(err)

settings_test.go

@@ -48,3 +48,36 @@ func TestMmapSizes(t *testing.T) {
 		t.Fatal("Sizes don't match")
 	}
 }
+
+func TestEnableCaching(t *testing.T) {
+	err := EnableCaching(false)
+	checkFatal(t, err)
+
+	err = EnableCaching(true)
+	checkFatal(t, err)
+}
+
+func TestGetCachedMemory(t *testing.T) {
+	current, allowed, err := GetCachedMemory()
+	checkFatal(t, err)
+
+	if current < 0 {
+		t.Fatal("current < 0")
+	}
+
+	if allowed < 0 {
+		t.Fatal("allowed < 0")
+	}
+}
+
+func TestSetCacheMaxSize(t *testing.T) {
+	err := SetCacheMaxSize(0)
+	checkFatal(t, err)
+
+	err = SetCacheMaxSize(1024 * 1024)
+	checkFatal(t, err)
+
+	// revert to default 256MB
+	err = SetCacheMaxSize(256 * 1024 * 1024)
+	checkFatal(t, err)
+}