fix: omit status field when empty (#2654)

This PR omits that `status` field when it is empty. The `status` field
is always empty in `generate-request.json`, so this change ensures that
`generate-request.json` no longer contains the `status` field. This
aligns with what we have in the docs:
https://github.com/googleapis/librarian/blob/main/doc/language-onboarding.md

We only need the `status` field in `configure-request.json`, and the
value is expected to be either `new` or `existing` as per the above
docs.

Author: parthea

internal/config/state.go

@@ -245,7 +245,7 @@ type API struct {
 	ServiceConfig string `yaml:"service_config" json:"service_config"`
 	// The status of the API, one of "new" or "existing".
 	// This field is ignored when writing to state.yaml.
-	Status string `yaml:"-" json:"status"`
+	Status string `yaml:"-" json:"status,omitempty"`
 }
 
 // Validate checks that the API is valid.

internal/docker/docker_test.go

@@ -715,6 +715,36 @@ func TestWriteLibraryState(t *testing.T) {
 			filename: "a-library-example.json",
 			wantFile: "successful-marshaling-and-writing.json",
 		},
+		{
+			name: "omit empty status",
+			state: &config.LibrarianState{
+				Image: "v1.0.0",
+				Libraries: []*config.LibraryState{
+					{
+						ID:      "google-cloud-go",
+						Version: "1.0.0",
+						APIs: []*config.API{
+							{
+								Path:          "google/cloud/compute/v1",
+								ServiceConfig: "example_service_config.yaml",
+							},
+						},
+						SourceRoots: []string{
+							"src/example/path",
+						},
+						PreserveRegex: []string{
+							"example-preserve-regex",
+						},
+						RemoveRegex: []string{
+							"example-remove-regex",
+						},
+					},
+				},
+			},
+			path:     os.TempDir(),
+			filename: "omit-empty-status.json",
+			wantFile: "omit-empty-status.json",
+		},
 		{
 			name:     "empty library state",
 			state:    &config.LibrarianState{},

testdata/test-write-library-state/omit-empty-status.json

@@ -0,0 +1,19 @@
+{
+  "id": "google-cloud-go",
+  "version": "1.0.0",
+  "apis": [
+    {
+      "path": "google/cloud/compute/v1",
+      "service_config": "example_service_config.yaml"
+    }
+  ],
+  "source_roots": [
+    "src/example/path"
+  ],
+  "preserve_regex": [
+    "example-preserve-regex"
+  ],
+  "remove_regex": [
+    "example-remove-regex"
+  ]
+}