test: Enhance Coverage + CI (#1055)

Reviewed-on: https://gitea.com/gitea/runner/pulls/1055
Reviewed-by: Lunny Xiao <xiaolunwen@gmail.com>
Co-authored-by: bircni <bircni@icloud.com>

internal/pkg/labels/labels_test.go

@@ -61,3 +61,75 @@ func TestParse(t *testing.T) {
 		})
 	}
 }
+
+// mustParse parses the given label strings, failing the test on any error.
+func mustParse(t *testing.T, strs ...string) Labels {
+	t.Helper()
+	ls := make(Labels, 0, len(strs))
+	for _, s := range strs {
+		l, err := Parse(s)
+		require.NoError(t, err)
+		ls = append(ls, l)
+	}
+	return ls
+}
+
+func TestRequireDocker(t *testing.T) {
+	tests := []struct {
+		name string
+		strs []string
+		want bool
+	}{
+		{"empty", nil, false},
+		{"only host", []string{"ubuntu:host", "self-hosted"}, false},
+		{"has docker", []string{"ubuntu:host", "ubuntu:docker://node:18"}, true},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			require.Equal(t, tt.want, mustParse(t, tt.strs...).RequireDocker())
+		})
+	}
+}
+
+func TestPickPlatform(t *testing.T) {
+	ls := mustParse(t,
+		"ubuntu:docker://node:18",
+		"self-hosted:host",
+	)
+
+	tests := []struct {
+		name   string
+		runsOn []string
+		want   string
+	}{
+		{"docker strips leading slashes", []string{"ubuntu"}, "node:18"},
+		{"host maps to self-hosted marker", []string{"self-hosted"}, "-self-hosted"},
+		{"first match wins", []string{"self-hosted", "ubuntu"}, "-self-hosted"},
+		{"unknown falls back to default", []string{"windows"}, "docker.gitea.com/runner-images:ubuntu-latest"},
+		{"no runsOn falls back to default", nil, "docker.gitea.com/runner-images:ubuntu-latest"},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			require.Equal(t, tt.want, ls.PickPlatform(tt.runsOn))
+		})
+	}
+}
+
+func TestNames(t *testing.T) {
+	ls := mustParse(t, "ubuntu:docker://node:18", "self-hosted:host")
+	require.Equal(t, []string{"ubuntu", "self-hosted"}, ls.Names())
+	require.Empty(t, Labels{}.Names())
+}
+
+func TestToStrings(t *testing.T) {
+	ls := mustParse(t,
+		"ubuntu:docker://node:18",
+		"self-hosted:host",
+		"bare",
+	)
+	require.Equal(t, []string{
+		"ubuntu:docker://node:18",
+		"self-hosted:host",
+		"bare:host",
+	}, ls.ToStrings())
+}