Add blob typechecker (#5519)

Signed-off-by: ddl-rliu <[email protected]>

flytepropeller/pkg/compiler/validators/typing.go

@@ -72,6 +72,26 @@ func (t mapTypeChecker) CastsFrom(upstreamType *flyte.LiteralType) bool {
 	return false
 }
 
+type blobTypeChecker struct {
+	literalType *flyte.LiteralType
+}
+
+// CastsFrom checks that the target blob type can be cast to the current blob type. When the blob has no format
+// specified, it accepts all blob inputs since it is generic.
+func (t blobTypeChecker) CastsFrom(upstreamType *flyte.LiteralType) bool {
+	blobType := upstreamType.GetBlob()
+	if blobType == nil {
+		return false
+	}
+
+	// Empty blobs should match any blob.
+	if blobType.GetFormat() == "" || t.literalType.GetBlob().GetFormat() == "" {
+		return true
+	}
+
+	return blobType.GetFormat() == t.literalType.GetBlob().GetFormat()
+}
+
 type collectionTypeChecker struct {
 	literalType *flyte.LiteralType
 }
@@ -333,6 +353,10 @@ func getTypeChecker(t *flyte.LiteralType) typeChecker {
 		return mapTypeChecker{
 			literalType: t,
 		}
+	case *flyte.LiteralType_Blob:
+		return blobTypeChecker{
+			literalType: t,
+		}
 	case *flyte.LiteralType_Schema:
 		return schemaTypeChecker{
 			literalType: t,

flytepropeller/pkg/compiler/validators/typing_test.go

@@ -893,3 +893,58 @@ func TestStructuredDatasetCasting(t *testing.T) {
 		assert.True(t, castable, "StructuredDataset are nullable")
 	})
 }
+
+func TestBlobCasting(t *testing.T) {
+	emptyBlob := &core.LiteralType{
+		Type: &core.LiteralType_Blob{
+			Blob: &core.BlobType{
+				Format: "",
+			},
+		},
+	}
+	genericBlob := &core.LiteralType{
+		Type: &core.LiteralType_Blob{
+			Blob: &core.BlobType{
+				Format: "csv",
+			},
+		},
+	}
+	mismatchedFormatBlob := &core.LiteralType{
+		Type: &core.LiteralType_Blob{
+			Blob: &core.BlobType{
+				Format: "pdf",
+			},
+		},
+	}
+
+	t.Run("BaseCase_GenericBlob", func(t *testing.T) {
+		castable := AreTypesCastable(genericBlob, genericBlob)
+		assert.True(t, castable, "Blob() should be castable to Blob()")
+	})
+
+	t.Run("GenericToEmptyFormat", func(t *testing.T) {
+		castable := AreTypesCastable(genericBlob, emptyBlob)
+		assert.True(t, castable, "Blob(format='csv') should be castable to Blob()")
+	})
+
+	t.Run("EmptyFormatToGeneric", func(t *testing.T) {
+		castable := AreTypesCastable(genericBlob, emptyBlob)
+		assert.True(t, castable, "Blob() should be castable to Blob(format='csv')")
+	})
+
+	t.Run("MismatchedFormat", func(t *testing.T) {
+		castable := AreTypesCastable(genericBlob, mismatchedFormatBlob)
+		assert.False(t, castable, "Blob(format='csv') should not be castable to Blob(format='pdf')")
+	})
+
+	t.Run("BlobsAreNullable", func(t *testing.T) {
+		castable := AreTypesCastable(
+			&core.LiteralType{
+				Type: &core.LiteralType_Simple{
+					Simple: core.SimpleType_NONE,
+				},
+			},
+			genericBlob)
+		assert.False(t, castable, "Blob is not nullable")
+	})
+}