Fix record signatures based on data provided by mappings. (#507)

Reads "extras/record_signatures.json" from mappings jar, just works with yarn.

Mojmap:

```
mappings loom.layered {
   officialMojangMappings()
   signatureFix("net.fabricmc:yarn:21w38a+build.9:v2")
}
```

2 files changed, 2 insertions, 2 deletions

diff --git a/src/test/groovy/net/fabricmc/loom/test/LoomTestConstants.groovy b/src/test/groovy/net/fabricmc/loom/test/LoomTestConstants.groovy
index 57c0f2cc..e478d61b 100644
--- a/src/test/groovy/net/fabricmc/loom/test/LoomTestConstants.groovy
+++ b/src/test/groovy/net/fabricmc/loom/test/LoomTestConstants.groovy
@@ -26,7 +26,7 @@ package net.fabricmc.loom.test
 
 class LoomTestConstants {
     public final static String DEFAULT_GRADLE = "7.0.1"
-    public final static String PRE_RELEASE_GRADLE = "7.3-20210906222431+0000"
+    public final static String PRE_RELEASE_GRADLE = "7.4-20210926222420+0000"
 
     public final static String[] STANDARD_TEST_VERSIONS = [DEFAULT_GRADLE, PRE_RELEASE_GRADLE]
 }
diff --git a/src/test/groovy/net/fabricmc/loom/test/unit/layeredmappings/LayeredMappingsSpecification.groovy b/src/test/groovy/net/fabricmc/loom/test/unit/layeredmappings/LayeredMappingsSpecification.groovy
index 1fba03dc..f751f3ab 100644
--- a/src/test/groovy/net/fabricmc/loom/test/unit/layeredmappings/LayeredMappingsSpecification.groovy
+++ b/src/test/groovy/net/fabricmc/loom/test/unit/layeredmappings/LayeredMappingsSpecification.groovy
@@ -85,7 +85,7 @@ abstract class LayeredMappingsSpecification extends Specification implements Lay
     MemoryMappingTree getLayeredMappings(MappingsSpec<? extends MappingLayer>... specs) {
         LayeredMappingSpec spec = new LayeredMappingSpec(specs.toList())
         LayeredMappingsProcessor processor = new LayeredMappingsProcessor(spec)
-        return processor.getMappings(mappingContext)
+        return processor.getMappings(processor.resolveLayers(mappingContext))
     }
 
     String getTiny(MemoryMappingTree mappingTree) {