doc: be clear about Go special cases

README.md

@@ -8,7 +8,7 @@ This repository contains fixtures for standard IPLD codecs. It is used to verify
 
 The [fixtures](./fixtures/) directory contains a suite of test data, where each subdirectory comprises an encoded IPLD block in the formats that are supported for that data. A file containing the binary encoded form of that block has the name `<CID>.<codec-name>`, where the `CID` is the CIDv1 using a SHA2-256 multihash of the block for that codec. The `codec-name` is the standard codec name as found in the [multicodec table](https://github.com/multiformats/multicodec/blob/master/table.csv).
 
-Fixtures are also available in CAR format, in the [./fixtures.car](./fixtures.car) file, with every valid variation stored as a separate block.
+Fixtures are also available in CAR format, in the [./fixtures.car](./fixtures.car) file, with every valid variation stored as a separate block. (Note that this file includes blocks that may not be readable on some systems, e.g. Kubo because of the currently [unsupported Go edge cases](./go/special_cases.go)).
 
 Codec implementations are expected to be able to:
 

go/codecs_test.go

@@ -170,8 +170,7 @@ func testNegativeFixtureEncode(codecName string, fixture negativeFixtureEncode)
 		err = encoder(node, &buf)
 		if err == nil {
 			t.Errorf("should error on encode")
-		}
-		if !strings.EqualFold(err.Error(), fixture.Error) {
+		} else if !strings.EqualFold(err.Error(), fixture.Error) {
 			t.Logf("error mismatch: [%s] ~= [%s]", err.Error(), fixture.Error)
 		}
 	}

go/special_cases.go

@@ -4,9 +4,14 @@ type FixtureName = string
 type FixtureBlacklistReason = string
 
 var FixtureBlacklist = map[FixtureName]FixtureBlacklistReason{
-	"int--11959030306112471732":            "integer out of int64 range",
-	"int-11959030306112471731":             "integer out of int64 range",
-	"int-18446744073709551615":             "integer out of int64 range",
+	// negative integer outside of the int64 range, no support for that in Go
+	"int--11959030306112471732": "integer out of int64 range",
+	// dag-json strconv parsing error, out of int64 range
+	"int-11959030306112471731": "integer out of int64 range",
+	// dag-json strconv parsing error, out of int64 range
+	"int-18446744073709551615": "integer out of int64 range",
+	// dag-pb codec not strict on encoding unordered named link lists, should
+	// error but does not for these two:
 	"dag-pb/encode/bad sort":               "pre-sort not required",
 	"dag-pb/encode/bad sort (incl length)": "pre-sort not required",
 }