2 files changed, 264 insertions, 0 deletions
diff --git a/cli/internal/inference/inference.go b/cli/internal/inference/inference.go
new file mode 100644
index 0000000..5d6d34f
--- /dev/null
+++ b/cli/internal/inference/inference.go
@@ -0,0 +1,167 @@
+package inference
+
+import "github.com/vercel/turbo/cli/internal/fs"
+
+// Framework is an identifier for something that we wish to inference against.
+type Framework struct {
+	Slug            string
+	EnvMatcher      string
+	DependencyMatch matcher
+}
+
+type matcher struct {
+	strategy     matchStrategy
+	dependencies []string
+}
+
+type matchStrategy int
+
+const (
+	all matchStrategy = iota + 1
+	some
+)
+
+var _frameworks = []Framework{
+	{
+		Slug:       "blitzjs",
+		EnvMatcher: "^NEXT_PUBLIC_",
+		DependencyMatch: matcher{
+			strategy:     all,
+			dependencies: []string{"blitz"},
+		},
+	},
+	{
+		Slug:       "nextjs",
+		EnvMatcher: "^NEXT_PUBLIC_",
+		DependencyMatch: matcher{
+			strategy:     all,
+			dependencies: []string{"next"},
+		},
+	},
+	{
+		Slug:       "gatsby",
+		EnvMatcher: "^GATSBY_",
+		DependencyMatch: matcher{
+			strategy:     all,
+			dependencies: []string{"gatsby"},
+		},
+	},
+	{
+		Slug:       "astro",
+		EnvMatcher: "^PUBLIC_",
+		DependencyMatch: matcher{
+			strategy:     all,
+			dependencies: []string{"astro"},
+		},
+	},
+	{
+		Slug:       "solidstart",
+		EnvMatcher: "^VITE_",
+		DependencyMatch: matcher{
+			strategy:     all,
+			dependencies: []string{"solid-js", "solid-start"},
+		},
+	},
+	{
+		Slug:       "vue",
+		EnvMatcher: "^VUE_APP_",
+		DependencyMatch: matcher{
+			strategy:     all,
+			dependencies: []string{"@vue/cli-service"},
+		},
+	},
+	{
+		Slug:       "sveltekit",
+		EnvMatcher: "^VITE_",
+		DependencyMatch: matcher{
+			strategy:     all,
+			dependencies: []string{"@sveltejs/kit"},
+		},
+	},
+	{
+		Slug:       "create-react-app",
+		EnvMatcher: "^REACT_APP_",
+		DependencyMatch: matcher{
+			strategy:     some,
+			dependencies: []string{"react-scripts", "react-dev-utils"},
+		},
+	},
+	{
+		Slug:       "nuxtjs",
+		EnvMatcher: "^NUXT_ENV_",
+		DependencyMatch: matcher{
+			strategy:     some,
+			dependencies: []string{"nuxt", "nuxt-edge", "nuxt3", "nuxt3-edge"},
+		},
+	},
+	{
+		Slug:       "redwoodjs",
+		EnvMatcher: "^REDWOOD_ENV_",
+		DependencyMatch: matcher{
+			strategy:     all,
+			dependencies: []string{"@redwoodjs/core"},
+		},
+	},
+	{
+		Slug:       "vite",
+		EnvMatcher: "^VITE_",
+		DependencyMatch: matcher{
+			strategy:     all,
+			dependencies: []string{"vite"},
+		},
+	},
+	{
+		Slug:       "sanity",
+		EnvMatcher: "^SANITY_STUDIO_",
+		DependencyMatch: matcher{
+			strategy:     all,
+			dependencies: []string{"@sanity/cli"},
+		},
+	},
+}
+
+func (m matcher) match(pkg *fs.PackageJSON) bool {
+	deps := pkg.UnresolvedExternalDeps
+	// only check dependencies if we're in a non-monorepo
+	if pkg.Workspaces != nil && len(pkg.Workspaces) == 0 {
+		deps = pkg.Dependencies
+	}
+
+	if m.strategy == all {
+		for _, dependency := range m.dependencies {
+			_, exists := deps[dependency]
+			if !exists {
+				return false
+			}
+		}
+		return true
+	}
+
+	// m.strategy == some
+	for _, dependency := range m.dependencies {
+		_, exists := deps[dependency]
+		if exists {
+			return true
+		}
+	}
+	return false
+}
+
+func (f Framework) match(pkg *fs.PackageJSON) bool {
+	return f.DependencyMatch.match(pkg)
+}
+
+// InferFramework returns a reference to a matched framework
+func InferFramework(pkg *fs.PackageJSON) *Framework {
+	if pkg == nil {
+		return nil
+	}
+
+	for _, candidateFramework := range _frameworks {
+		if candidateFramework.match(pkg) {
+			return &candidateFramework
+		}
+	}
+
+	return nil
+}
diff --git a/cli/internal/inference/inference_test.go b/cli/internal/inference/inference_test.go
new file mode 100644
index 0000000..ed82ecc
--- /dev/null
+++ b/cli/internal/inference/inference_test.go
@@ -0,0 +1,97 @@
+package inference
+
+import (
+	"reflect"
+	"testing"
+
+	"github.com/vercel/turbo/cli/internal/fs"
+)
+
+func getFrameworkBySlug(slug string) *Framework {
+	for _, framework := range _frameworks {
+		if framework.Slug == slug {
+			return &framework
+		}
+	}
+	panic("that framework doesn't exist")
+}
+
+func TestInferFramework(t *testing.T) {
+	tests := []struct {
+		name string
+		pkg  *fs.PackageJSON
+		want *Framework
+	}{
+		{
+			name: "Hello world",
+			pkg:  nil,
+			want: nil,
+		},
+		{
+			name: "Empty dependencies",
+			pkg:  &fs.PackageJSON{UnresolvedExternalDeps: map[string]string{}},
+			want: nil,
+		},
+		{
+			name: "Finds Blitz",
+			pkg: &fs.PackageJSON{UnresolvedExternalDeps: map[string]string{
+				"blitz": "*",
+			}},
+			want: getFrameworkBySlug("blitzjs"),
+		},
+		{
+			name: "Order is preserved (returns blitz, not next)",
+			pkg: &fs.PackageJSON{UnresolvedExternalDeps: map[string]string{
+				"blitz": "*",
+				"next":  "*",
+			}},
+			want: getFrameworkBySlug("blitzjs"),
+		},
+		{
+			name: "Finds next without blitz",
+			pkg: &fs.PackageJSON{UnresolvedExternalDeps: map[string]string{
+				"next": "*",
+			}},
+			want: getFrameworkBySlug("nextjs"),
+		},
+		{
+			name: "match strategy of all works (solid)",
+			pkg: &fs.PackageJSON{UnresolvedExternalDeps: map[string]string{
+				"solid-js":    "*",
+				"solid-start": "*",
+			}},
+			want: getFrameworkBySlug("solidstart"),
+		},
+		{
+			name: "match strategy of some works (nuxt)",
+			pkg: &fs.PackageJSON{UnresolvedExternalDeps: map[string]string{
+				"nuxt3": "*",
+			}},
+			want: getFrameworkBySlug("nuxtjs"),
+		},
+		{
+			name: "match strategy of some works (c-r-a)",
+			pkg: &fs.PackageJSON{UnresolvedExternalDeps: map[string]string{
+				"react-scripts": "*",
+			}},
+			want: getFrameworkBySlug("create-react-app"),
+		},
+		{
+			name: "Finds next in non monorepo",
+			pkg: &fs.PackageJSON{
+				Dependencies: map[string]string{
+					"next": "*",
+				},
+				Workspaces: []string{},
+			},
+			want: getFrameworkBySlug("nextjs"),
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := InferFramework(tt.pkg); !reflect.DeepEqual(got, tt.want) {
+				t.Errorf("InferFramework() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}