cleaned up sign-compare unittest build warnings

addresses issue #3624

test/unit/Common/utStandardShapes.cpp

@@ -46,7 +46,7 @@ TEST_F( utStandardShapes, testMakeMesh ) {
     Assimp::StandardShapes::MakeSphere(1, positions);
 
     // Make mesh
-    const auto numIndicesPerPrimitive = 3;
+    const auto numIndicesPerPrimitive = 3u;
     aiMesh *aiMeshPtr = Assimp::StandardShapes::MakeMesh(positions, numIndicesPerPrimitive);
 
     // The mNumIndices member of the second face is now incorrect

test/unit/utFBXImporterExporter.cpp

@@ -324,7 +324,7 @@ TEST_F(utFBXImporterExporter, importMaxPbrMaterialsMetalRoughness) {
     ASSERT_NE(nullptr, scene);
     ASSERT_TRUE(scene->mRootNode);
 
-    ASSERT_EQ(scene->mNumMaterials, 1);
+    ASSERT_EQ(scene->mNumMaterials, 1u);
     const aiMaterial* mat = scene->mMaterials[0];
     aiString texture;
     ASSERT_EQ(mat->Get(AI_MATKEY_TEXTURE(aiTextureType_BASE_COLOR, 0), texture), AI_SUCCESS);
@@ -377,7 +377,7 @@ TEST_F(utFBXImporterExporter, importMaxPbrMaterialsSpecularGloss) {
     ASSERT_NE(nullptr, scene);
     ASSERT_TRUE(scene->mRootNode);
 
-    ASSERT_EQ(scene->mNumMaterials, 1);
+    ASSERT_EQ(scene->mNumMaterials, 1u);
     const aiMaterial* mat = scene->mMaterials[0];
     aiString texture;
     ASSERT_EQ(mat->Get(AI_MATKEY_TEXTURE(aiTextureType_BASE_COLOR, 0), texture), AI_SUCCESS);

test/unit/utFindDegenerates.cpp

@@ -201,8 +201,8 @@ TEST_F(FindDegeneratesProcessTest, meshRemoval) {
 
     mProcess->Execute(scene.get());    
 
-    EXPECT_EQ(scene->mNumMeshes, 1);
+    EXPECT_EQ(scene->mNumMeshes, 1u);
     EXPECT_EQ(scene->mMeshes[0], meshWhichSurvives);
-    EXPECT_EQ(scene->mRootNode->mNumMeshes, 1);
-    EXPECT_EQ(scene->mRootNode->mMeshes[0], 0);    
+    EXPECT_EQ(scene->mRootNode->mNumMeshes, 1u);
+    EXPECT_EQ(scene->mRootNode->mMeshes[0], 0u);    
 }