Better testing for JSON deserialisation

Adds tests to ensure that JSON deserialisation from program arguments
takes place. This was a testing blind spot, which led to a brief
regression:

https://gitlab.com/gitlab-org/gitlab-shell/merge_requests/280

go/cmd/gitaly-receive-pack/main_test.go

+package main
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+	pb "gitlab.com/gitlab-org/gitaly-proto/go/gitalypb"
+)
+
+func Test_deserialize(t *testing.T) {
+	tests := []struct {
+		name        string
+		requestJSON string
+		want        *pb.SSHReceivePackRequest
+		wantErr     bool
+	}{
+		{
+			name:        "empty",
+			requestJSON: "",
+			want:        nil,
+			wantErr:     true,
+		},
+		{
+			name:        "empty_hash",
+			requestJSON: "{}",
+			want:        &pb.SSHReceivePackRequest{},
+			wantErr:     false,
+		},
+		{
+			name:        "nil",
+			requestJSON: "null",
+			want:        &pb.SSHReceivePackRequest{},
+			wantErr:     false,
+		},
+		{
+			name:        "values",
+			requestJSON: `{"gl_id": "1234"}`,
+			want:        &pb.SSHReceivePackRequest{GlId: "1234"},
+			wantErr:     false,
+		},
+		{
+			name:        "invalid_json",
+			requestJSON: `{"gl_id": "1234`,
+			want:        nil,
+			wantErr:     true,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got, err := deserialize(tt.requestJSON)
+			require.EqualValues(t, got, tt.want, "Got %+v, wanted %+v", got, tt.want)
+			if tt.wantErr {
+				require.Error(t, err, "Wanted an error, got %+v", err)
+			} else {
+				require.NoError(t, err, "Wanted no error, got %+v", err)
+			}
+		})
+	}
+}

go/cmd/gitaly-upload-archive/main_test.go

+package main
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+	pb "gitlab.com/gitlab-org/gitaly-proto/go/gitalypb"
+)
+
+func Test_deserialize(t *testing.T) {
+	tests := []struct {
+		name        string
+		requestJSON string
+		want        *pb.SSHUploadArchiveRequest
+		wantErr     bool
+	}{
+		{
+			name:        "empty",
+			requestJSON: "",
+			want:        nil,
+			wantErr:     true,
+		},
+		{
+			name:        "empty_hash",
+			requestJSON: "{}",
+			want:        &pb.SSHUploadArchiveRequest{},
+			wantErr:     false,
+		},
+		{
+			name:        "nil",
+			requestJSON: "null",
+			want:        &pb.SSHUploadArchiveRequest{},
+			wantErr:     false,
+		},
+		{
+			name:        "values",
+			requestJSON: `{"repository": { "storage_name": "12345"} }`,
+			want:        &pb.SSHUploadArchiveRequest{Repository: &pb.Repository{StorageName: "12345"}},
+			wantErr:     false,
+		},
+		{
+			name:        "invalid_json",
+			requestJSON: `{"gl_id": "1234`,
+			want:        nil,
+			wantErr:     true,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got, err := deserialize(tt.requestJSON)
+			require.EqualValues(t, got, tt.want, "Got %+v, wanted %+v", got, tt.want)
+			if tt.wantErr {
+				require.Error(t, err, "Wanted an error, got %+v", err)
+			} else {
+				require.NoError(t, err, "Wanted no error, got %+v", err)
+			}
+		})
+	}
+}

go/cmd/gitaly-upload-pack/main_test.go

+package main
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+	pb "gitlab.com/gitlab-org/gitaly-proto/go/gitalypb"
+)
+
+func Test_deserialize(t *testing.T) {
+	tests := []struct {
+		name        string
+		requestJSON string
+		want        *pb.SSHUploadPackRequest
+		wantErr     bool
+	}{
+		{
+			name:        "empty",
+			requestJSON: "",
+			want:        nil,
+			wantErr:     true,
+		},
+		{
+			name:        "empty_hash",
+			requestJSON: "{}",
+			want:        &pb.SSHUploadPackRequest{},
+			wantErr:     false,
+		},
+		{
+			name:        "nil",
+			requestJSON: "null",
+			want:        &pb.SSHUploadPackRequest{},
+			wantErr:     false,
+		},
+		{
+			name:        "values",
+			requestJSON: `{"repository": { "storage_name": "12345"} }`,
+			want:        &pb.SSHUploadPackRequest{Repository: &pb.Repository{StorageName: "12345"}},
+			wantErr:     false,
+		},
+		{
+			name:        "invalid_json",
+			requestJSON: `{"gl_id": "1234`,
+			want:        nil,
+			wantErr:     true,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got, err := deserialize(tt.requestJSON)
+			require.EqualValues(t, got, tt.want, "Got %+v, wanted %+v", got, tt.want)
+			if tt.wantErr {
+				require.Error(t, err, "Wanted an error, got %+v", err)
+			} else {
+				require.NoError(t, err, "Wanted no error, got %+v", err)
+			}
+		})
+	}
+}