vmm_tests: Fix build requirements function when parsing vmm_test macros (#2218)

The build_requirements function did not take into account all the
possible combinations for a VmmBackend to be configured. This allowed
for some discrepancy when generating the test case host capabilities
requirements depending on how the vmm backend was being configured. This
PR refactors the make_vmm_test so that resolving the vmm backend happens
earlier in the function, and the resolved value is the one that is used
throughout.

---------

Co-authored-by: Daman Mulye <[email protected]>

Author: damanm24

vmm_tests/vmm_test_macros/src/lib.rs

@@ -91,13 +91,12 @@ fn arch_to_tokens(arch: MachineArch) -> TokenStream {
 }
 
 impl Config {
-    fn name_prefix(&self, specific_vmm: Option<Vmm>) -> String {
+    fn name_prefix(&self, resolved_vmm: Vmm) -> String {
         let arch_prefix = arch_to_str(self.arch);
 
-        let vmm_prefix = match (specific_vmm, self.vmm) {
-            (_, Some(Vmm::OpenVmm)) | (Some(Vmm::OpenVmm), None) => "openvmm",
-            (_, Some(Vmm::HyperV)) | (Some(Vmm::HyperV), None) => "hyperv",
-            _ => "",
+        let vmm_prefix = match resolved_vmm {
+            Vmm::OpenVmm => "openvmm",
+            Vmm::HyperV => "hyperv",
         };
 
         let firmware_prefix = match &self.firmware {
@@ -675,10 +674,22 @@ fn make_vmm_test(
     let mut tests = TokenStream::new();
     // FUTURE: compute all this in code instead of in the macro.
     for config in args.configs {
-        let name = format!("{}_{original_name}", config.name_prefix(specific_vmm));
+        // Resolve the VMM backend early by combining specific_vmm and config.vmm
+        let resolved_vmm = match (specific_vmm, config.vmm) {
+            (Some(Vmm::HyperV), Some(Vmm::HyperV))
+            | (Some(Vmm::HyperV), None)
+            | (None, Some(Vmm::HyperV)) => Vmm::HyperV,
+            (Some(Vmm::OpenVmm), Some(Vmm::OpenVmm))
+            | (Some(Vmm::OpenVmm), None)
+            | (None, Some(Vmm::OpenVmm)) => Vmm::OpenVmm,
+            (None, None) => return Err(Error::new(config.span, "vmm must be specified")),
+            _ => return Err(Error::new(config.span, "vmm mismatch")),
+        };
+
+        let name = format!("{}_{original_name}", config.name_prefix(resolved_vmm));
 
-        // Build requirements based on the configuration
-        let requirements = build_requirements(&config, &name);
+        // Build requirements based on the configuration and resolved VMM
+        let requirements = build_requirements(&config.firmware, &name, resolved_vmm);
         let requirements = if let Some(req) = requirements {
             quote! { Some(#req) }
         } else {
@@ -694,24 +705,17 @@ fn make_vmm_test(
         };
         let arch = arch_to_tokens(config.arch);
 
-        let (cfg_conditions, artifacts, petri_vm_config) = match (specific_vmm, config.vmm) {
-            (Some(Vmm::HyperV), Some(Vmm::HyperV))
-            | (Some(Vmm::HyperV), None)
-            | (None, Some(Vmm::HyperV)) => (
+        let (cfg_conditions, artifacts, petri_vm_config) = match resolved_vmm {
+            Vmm::HyperV => (
                 quote!(#[cfg(windows)]),
                 quote!(::petri::PetriVmArtifacts::<::petri::hyperv::HyperVPetriBackend>),
                 quote!(::petri::PetriVmBuilder::<::petri::hyperv::HyperVPetriBackend>),
             ),
-
-            (Some(Vmm::OpenVmm), Some(Vmm::OpenVmm))
-            | (Some(Vmm::OpenVmm), None)
-            | (None, Some(Vmm::OpenVmm)) => (
+            Vmm::OpenVmm => (
                 quote!(),
                 quote!(::petri::PetriVmArtifacts::<::petri::openvmm::OpenVmmPetriBackend>),
                 quote!(::petri::PetriVmBuilder::<::petri::openvmm::OpenVmmPetriBackend>),
             ),
-            (None, None) => return Err(Error::new(config.span, "vmm must be specified")),
-            _ => return Err(Error::new(config.span, "vmm mismatch")),
         };
 
         let petri_vm_config = quote!(#petri_vm_config::new(&params, artifacts, &driver)?);
@@ -746,8 +750,8 @@ fn make_vmm_test(
     })
 }
 
-// Helper to build requirements TokenStream for a config and specific_vmm
-fn build_requirements(config: &Config, name: &str) -> Option<TokenStream> {
+// Helper to build requirements TokenStream for firmware and resolved VMM
+fn build_requirements(firmware: &Firmware, name: &str, resolved_vmm: Vmm) -> Option<TokenStream> {
     let mut requirement_expr: Option<TokenStream> = None;
     let mut is_vbs = false;
     // Add isolation requirement if specified
@@ -757,7 +761,7 @@ fn build_requirements(config: &Config, name: &str) -> Option<TokenStream> {
             ..
         },
         _,
-    ) = &config.firmware
+    ) = firmware
     {
         let isolation_requirement = match isolation {
             IsolationType::Vbs => {
@@ -803,7 +807,7 @@ fn build_requirements(config: &Config, name: &str) -> Option<TokenStream> {
         };
     }
 
-    let is_hyperv = config.vmm.is_some() && config.vmm == Some(Vmm::HyperV);
+    let is_hyperv = resolved_vmm == Vmm::HyperV;
 
     if is_hyperv && is_vbs {
         let hyperv_vbs_requirement_expr = quote!(