circleci: add test-assets and style jobs

Since assets tests can only run on go1.16 and later the matrix style job
list avoinds adding more conditionals to the job spec.

Signed-off-by: Jan Fajerski <jfajersk@redhat.com>

.circleci/config.yml

@@ -9,9 +9,6 @@ jobs:
     parameters:
       go_version:
         type: string
-      run_style:
-        type: boolean
-        default: false
       use_gomod_cache:
         type: boolean
         default: true
@@ -28,10 +25,57 @@ jobs:
     - run: make test
     - run: cd sigv4 && make test
     - when:
-        condition: << parameters.run_style >>
+        condition: << parameters.use_gomod_cache >>
+        steps:
+        - go/save-cache:
+            key: v1-go<< parameters.go_version >>
+    - store_test_results:
+        path: test-results
+  test-assets:
+    parameters:
+      go_version:
+        type: string
+      use_gomod_cache:
+        type: boolean
+        default: true
+    docker:
+    - image: circleci/golang:<< parameters.go_version >>
+    working_directory: /go/src/github.com/prometheus/common/assets
+    steps:
+    - checkout
+    - when:
+        condition: << parameters.use_gomod_cache >>
         steps:
-        - run: make style
-        - run: cd sigv4 && make style
+        - go/load-cache:
+            key: v1-go<< parameters.go_version >>
+    - run: make test
+    - when:
+        condition: << parameters.use_gomod_cache >>
+        steps:
+        - go/save-cache:
+            key: v1-go<< parameters.go_version >>
+    - store_test_results:
+        path: ../test-results
+  style:
+    parameters:
+      go_version:
+        type: string
+      use_gomod_cache:
+        type: boolean
+        default: true
+    docker:
+    - image: circleci/golang:<< parameters.go_version >>
+    working_directory: /go/src/github.com/prometheus/common
+    steps:
+    - checkout
+    - when:
+        condition: << parameters.use_gomod_cache >>
+        steps:
+        - go/load-cache:
+            key: v1-go<< parameters.go_version >>
+    - run: make style
+    - run: cd sigv4 && make style
+    - run: cd assets && make style
     - when:
         condition: << parameters.use_gomod_cache >>
         steps:
@@ -46,16 +90,15 @@ workflows:
     jobs:
     # Supported Go versions are synced with github.com/prometheus/client_golang.
     - test:
-        name: go-1-13
-        go_version: "1.13"
-    - test:
-        name: go-1-14
-        go_version: "1.14"
-    - test:
-        name: go-1-15
-        go_version: "1.15"
-    - test:
-        name: go-1-16
+        name: go-<< matrix.go_version >>
+        matrix:
+          parameters:
+            go_version: ["1.13", "1.14", "1.15", "1.16"]
+    - test-assets:
+        name: assets-go-<< matrix.go_version >>
+        matrix:
+          parameters:
+            go_version: ["1.16"]
+    - style:
+        name: style
         go_version: "1.16"
-        # Style is only checked against the latest supported Go version.
-        run_style: true