ef_tests: skipped tests and bls_setting support

tests/ef_tests/src/bls_setting.rs

@@ -0,0 +1,30 @@
+use self::BlsSetting::*;
+use crate::error::Error;
+use serde_repr::Deserialize_repr;
+
+// TODO: use this in every test case
+#[derive(Deserialize_repr, Debug, Clone, Copy)]
+#[repr(u8)]
+pub enum BlsSetting {
+    Flexible = 0,
+    Required = 1,
+    Ignored = 2,
+}
+
+impl Default for BlsSetting {
+    fn default() -> Self {
+        Flexible
+    }
+}
+
+impl BlsSetting {
+    /// Check the BLS setting and skip the test if it isn't compatible with the crypto config.
+    pub fn check(self) -> Result<(), Error> {
+        match self {
+            Flexible => Ok(()),
+            Required if !cfg!(feature = "fake_crypto") => Ok(()),
+            Ignored if cfg!(feature = "fake_crypto") => Ok(()),
+            _ => Err(Error::Skipped),
+        }
+    }
+}