Add eigen3 test targets to satisfy layering checks

Signed-off-by: Shameek Ganguly <[email protected]>

eigen3/BUILD.bazel

@@ -30,22 +30,6 @@ cc_library(
     ],
 )
 
-test_sources = glob(
-    [
-        "src/*_TEST.cc",
-    ],
-)
-
-[cc_test(
-    name = src.replace("/", "_").replace(".cc", "").replace("src_", ""),
-    srcs = [src],
-    deps = [
-        ":eigen3",
-        "@gtest",
-        "@gtest//:gtest_main",
-    ],
-) for src in test_sources]
-
 cc_library(
     name = "Conversions",
     hdrs = ["include/gz/math/eigen3/Conversions.hh"],
@@ -61,6 +45,16 @@ cc_library(
     ],
 )
 
+cc_test(
+    name = "Conversions_TEST",
+    srcs = ["src/Conversions_TEST.cc"],
+    deps = [
+        ":Conversions",
+        "@gtest",
+        "@gtest//:gtest_main",
+    ],
+)
+
 cc_library(
     name = "Util",
     hdrs = ["include/gz/math/eigen3/Util.hh"],
@@ -76,3 +70,13 @@ cc_library(
         "@eigen3",
     ],
 )
+
+cc_test(
+    name = "Util_TEST",
+    srcs = ["src/Util_TEST.cc"],
+    deps = [
+        ":Util",
+        "@gtest",
+        "@gtest//:gtest_main",
+    ],
+)