wa-lang.org/wazero@v1.0.2/cmd/wazero/compositefs_test.go

package main

import (
	"bytes"
	"embed"
	"fmt"
	"io/fs"
	"testing"
	"testing/fstest"

	"wa-lang.org/wazero/internal/testing/require"
)

//go:embed testdata/fs
var testFS embed.FS

func TestCompositeFS(t *testing.T) {
	tests := []struct {
		name    string
		fs      *compositeFS
		path    string
		content string
	}{
		{
			name: "empty",
			fs:   &compositeFS{},
			path: "bear.txt",
		},
		{
			name: "single mount to root",
			fs: &compositeFS{
				paths: map[string]fs.FS{
					"": testFSSub(""),
				},
			},
			path:    "bear.txt",
			content: "pooh",
		},
		{
			name: "single mount to root",
			fs: &compositeFS{
				paths: map[string]fs.FS{
					"": testFSSub(""),
				},
			},
			path:    "fish/clownfish.txt",
			content: "nemo",
		},
		{
			name: "single mount to root",
			fs: &compositeFS{
				paths: map[string]fs.FS{
					"": testFSSub(""),
				},
			},
			path:    "mammals/primates/ape.txt",
			content: "king kong",
		},
		{
			name: "single mount to path",
			fs: &compositeFS{
				paths: map[string]fs.FS{
					"mammals": testFSSub(""),
				},
			},
			path:    "mammals/bear.txt",
			content: "pooh",
		},
		{
			name: "single mount to path",
			fs: &compositeFS{
				paths: map[string]fs.FS{
					"mammals": testFSSub(""),
				},
			},
			path: "mammals/whale.txt",
		},
		{
			name: "single mount to path",
			fs: &compositeFS{
				paths: map[string]fs.FS{
					"mammals": testFSSub(""),
				},
			},
			path: "bear.txt",
		},
		{
			name: "non-overlapping mounts",
			fs: &compositeFS{
				paths: map[string]fs.FS{
					"fish":    testFSSub("fish"),
					"mammals": testFSSub("mammals"),
				},
			},
			path:    "fish/clownfish.txt",
			content: "nemo",
		},
		{
			name: "non-overlapping mounts",
			fs: &compositeFS{
				paths: map[string]fs.FS{
					"fish":    testFSSub("fish"),
					"mammals": testFSSub("mammals"),
				},
			},
			path:    "mammals/whale.txt",
			content: "moby dick",
		},
		{
			name: "non-overlapping mounts",
			fs: &compositeFS{
				paths: map[string]fs.FS{
					"fish":    testFSSub("fish"),
					"mammals": testFSSub("mammals"),
				},
			},
			path:    "mammals/primates/ape.txt",
			content: "king kong",
		},
		{
			name: "non-overlapping mounts",
			fs: &compositeFS{
				paths: map[string]fs.FS{
					"fish":    testFSSub("fish"),
					"mammals": testFSSub("mammals"),
				},
			},
			path: "bear.txt",
		},
		{
			name: "overlapping mounts, deep first",
			fs: &compositeFS{
				paths: map[string]fs.FS{
					"animals/fish": testFSSub("fish"),
					"animals":      testFSSub("mammals"),
				},
			},
			path:    "animals/fish/clownfish.txt",
			content: "nemo",
		},
		{
			name: "overlapping mounts, deep first",
			fs: &compositeFS{
				paths: map[string]fs.FS{
					"animals/fish": testFSSub("fish"),
					"animals":      testFSSub("mammals"),
				},
			},
			path:    "animals/whale.txt",
			content: "moby dick",
		},
		{
			name: "overlapping mounts, deep first",
			fs: &compositeFS{
				paths: map[string]fs.FS{
					"animals/fish": testFSSub("fish"),
					"animals":      testFSSub("mammals"),
				},
			},
			path: "animals/bear.txt",
		},
		{
			name: "overlapping mounts, shallow first",
			fs: &compositeFS{
				paths: map[string]fs.FS{
					"animals":      testFSSub("mammals"),
					"animals/fish": testFSSub("fish"),
				},
			},
			path:    "animals/fish/clownfish.txt",
			content: "nemo",
		},
		{
			name: "overlapping mounts, shallow first",
			fs: &compositeFS{
				paths: map[string]fs.FS{
					"animals":      testFSSub("mammals"),
					"animals/fish": testFSSub("fish"),
				},
			},
			path:    "animals/whale.txt",
			content: "moby dick",
		},
		{
			name: "overlapping mounts, shallow first",
			fs: &compositeFS{
				paths: map[string]fs.FS{
					"animals":      testFSSub("mammals"),
					"animals/fish": testFSSub("fish"),
				},
			},
			path: "animals/bear.txt",
		},
	}

	for _, tc := range tests {
		tt := tc
		t.Run(fmt.Sprintf("%s - %s", tt.name, tt.path), func(t *testing.T) {
			content, err := fs.ReadFile(tt.fs, tt.path)
			if tt.content != "" {
				require.NoError(t, err)
				require.Equal(t, tt.content, string(bytes.TrimSpace(content)))
			} else {
				require.ErrorIs(t, err, fs.ErrNotExist)
			}
		})
	}
}

func TestFSTest(t *testing.T) {
	fs := &compositeFS{
		paths: map[string]fs.FS{
			// TestFS requires non-rooted paths to be read from current directory so we mount
			// both with . and no prefix.
			".": testFSSub(""),
			"":  testFSSub(""),
		},
	}

	require.NoError(t, fstest.TestFS(fs, "bear.txt"))
}

func testFSSub(path string) fs.FS {
	// Can't use filepath.Join because we need unix behavior even on Windows.
	p := "testdata/fs"
	if len(path) > 0 {
		p = fmt.Sprintf("%s/%s", p, path)
	}
	f, err := fs.Sub(testFS, p)
	if err != nil {
		panic(err)
	}
	return f
}