issues/65: Dump circular references (#66)

- Fixes: #65
- See: https://github.com/sanity-io/litter/blob/v1.5.5/README.md#circular-references

CHANGELOG.md

@@ -2,6 +2,10 @@
 
 Most recent version is listed first.  
 
+
+# v0.0.17
+- Add ability to dump items with circular references: https://github.com/komuw/kama/pull/66
+
 # v0.0.16
 - Update Go version: https://github.com/komuw/kama/pull/62
 - Add ability to dump private struct fields via config option: https://github.com/komuw/kama/pull/64

dump.go

@@ -105,6 +105,8 @@ func dump(val reflect.Value, hideZeroValues bool, indentLevel int) string {
 		if v.IsValid() {
 			if v.Type().Kind() == reflect.Struct {
 				fromPtr := true
+				// TODO: should we pass in `val`, itself instead of `v`
+				// that way `val.Pointer()` would happen inside `dumpStruct`
 				return dumpStruct(v, fromPtr, hideZeroValues, indentLevel)
 			} else {
 				return dumpNonStructPointer(v, hideZeroValues, indentLevel)
@@ -179,6 +181,10 @@ func dumpStruct(v reflect.Value, fromPtr, hideZeroValues bool, indentLevel int)
 		typeName = "&" + typeName
 	}
 
+	if indentLevel > cfg.MaxIndentLevel {
+		return fmt.Sprintf("%v: kama warning(indentation `%d` exceeds max of `%d`. Possible circular reference)", typeName, indentLevel, cfg.MaxIndentLevel)
+	}
+
 	sep := "\n"
 	fieldNameSep := strings.Repeat("  ", indentLevel)
 	lastBracketSep := strings.Repeat("  ", indentLevel-1)

kama.go

@@ -18,8 +18,13 @@ import (
 )
 
 var (
-	cfg     = Config{MaxLength: 14} //nolint:gochecknoglobals
-	onceCfg = &sync.Once{}          //nolint:gochecknoglobals
+	cfg = Config{ //nolint:gochecknoglobals
+		MaxLength:         14,
+		ShowPrivateFields: false,
+		MaxIndentLevel:    10,
+	}
+
+	onceCfg = &sync.Once{} //nolint:gochecknoglobals
 )
 
 // Config controls how printing is going to be done.
@@ -28,6 +33,9 @@ type Config struct {
 	MaxLength int
 	// ShowPrivateFields dictates whether private struct fields will be dumped.
 	ShowPrivateFields bool
+	// MaxIndentLevel is the maximum level of indentation/recursiveness to dump to.
+	// This is especially important to set if the thing you are dumping has circular references.
+	MaxIndentLevel int
 }
 
 // Dirp prints (to stdout) exported information of types, variables, packages, modules, imports
@@ -59,6 +67,13 @@ func Dir(i interface{}, c ...Config) string {
 				// https://github.com/golang/go/issues/38673#issuecomment-643885108
 				cfg.MaxLength = 10_000
 			}
+
+			if cfg.MaxIndentLevel < 1 {
+				cfg.MaxIndentLevel = 10 // ie, the default
+			}
+			if cfg.MaxIndentLevel > 100 {
+				cfg.MaxIndentLevel = 100
+			}
 		})
 	}
 

testdata/vars_test/TestCircularRef-with-NO-cirlce-DoNotShowPrivateFields.txt

@@ -0,0 +1,13 @@
+
+[
+NAME: github.com/komuw/kama.Client
+KIND: struct
+SIGNATURE: [*kama.Client kama.Client]
+FIELDS: [
+	Public string 
+	]
+METHODS: []
+SNIPPET: &Client{
+  Public: "PublicName",
+}
+]

testdata/vars_test/TestCircularRef-with-NO-cirlce-ShowPrivateFields.txt

@@ -0,0 +1,19 @@
+
+[
+NAME: github.com/komuw/kama.Client
+KIND: struct
+SIGNATURE: [*kama.Client kama.Client]
+FIELDS: [
+	Public string 
+	]
+METHODS: []
+SNIPPET: &Client{
+  Public: "PublicName",
+  srv: srvRef{
+    cli: &Client{
+      Public: "NewPubName",
+      srv: srvRef{},
+    },
+  },
+}
+]

testdata/vars_test/TestCircularRef-with-cirlce-DoNotShowPrivateFields.txt

@@ -0,0 +1,13 @@
+
+[
+NAME: github.com/komuw/kama.Client
+KIND: struct
+SIGNATURE: [*kama.Client kama.Client]
+FIELDS: [
+	Public string 
+	]
+METHODS: []
+SNIPPET: &Client{
+  Public: "PublicName",
+}
+]

testdata/vars_test/TestCircularRef-with-cirlce-ShowPrivateFields.txt

@@ -0,0 +1,36 @@
+
+[
+NAME: github.com/komuw/kama.Client
+KIND: struct
+SIGNATURE: [*kama.Client kama.Client]
+FIELDS: [
+	Public string 
+	]
+METHODS: []
+SNIPPET: &Client{
+  Public: "PublicName",
+  srv: srvRef{
+    cli: &Client{
+      Public: "PublicName",
+      srv: srvRef{
+        cli: &Client{
+          Public: "PublicName",
+          srv: srvRef{
+            cli: &Client{
+              Public: "PublicName",
+              srv: srvRef{
+                cli: &Client{
+                  Public: "PublicName",
+                  srv: srvRef{
+                    cli: &Client: kama warning(indentation `11` exceeds max of `10`. Possible circular reference),
+                  },
+                },
+              },
+            },
+          },
+        },
+      },
+    },
+  },
+}
+]

vars_test.go

@@ -560,3 +560,89 @@ func TestPublicPrivate(t *testing.T) {
 		})
 	}
 }
+
+type Client struct {
+	Public string
+	srv    srvRef
+}
+
+type srvRef struct {
+	cli *Client
+}
+
+func TestCircularRef(t *testing.T) {
+	// t.Parallel() // This cannot be ran in Parallel since it mutates a global var.
+
+	oldCfg := cfg
+
+	{ // Set the new config and schedule to return old config.
+		onceCfg = &sync.Once{}
+		t.Cleanup(func() {
+			cfg = oldCfg
+		})
+	}
+
+	for _, name := range []string{"ShowPrivateFields", "DoNotShowPrivateFields"} {
+		name := name
+		tName := fmt.Sprintf("TestCircularRef-with-cirlce-%s", name)
+
+		x := &Client{Public: "PublicName"}
+		x.srv.cli = x // circular
+
+		t.Run(tName, func(t *testing.T) {
+			// t.Parallel() // This cannot be ran in Parallel since it mutates a global var.
+
+			{ // Set the new config and schedule to return old config.
+				onceCfg = &sync.Once{}
+				t.Cleanup(func() {
+					cfg = oldCfg
+				})
+			}
+
+			var res string
+			switch name {
+			default:
+				t.Fatalf("option `%s` is not expected", name)
+			case "ShowPrivateFields":
+				res = Dir(x, Config{ShowPrivateFields: true})
+			case "DoNotShowPrivateFields":
+				res = Dir(x, Config{ShowPrivateFields: false})
+			}
+
+			path := getDataPath(t, "vars_test.go", tName)
+			dealWithTestData(t, path, res)
+		})
+	}
+
+	for _, name := range []string{"ShowPrivateFields", "DoNotShowPrivateFields"} {
+		name := name
+		tName := fmt.Sprintf("TestCircularRef-with-NO-cirlce-%s", name)
+
+		x := &Client{Public: "PublicName"}
+		x.srv.cli = &Client{Public: "NewPubName"} // no circle
+
+		t.Run(tName, func(t *testing.T) {
+			// t.Parallel() // This cannot be ran in Parallel since it mutates a global var.
+
+			{ // Set the new config and schedule to return old config.
+				onceCfg = &sync.Once{}
+				t.Cleanup(func() {
+					cfg = oldCfg
+				})
+			}
+
+			var res string
+			switch name {
+			default:
+				t.Fatalf("option `%s` is not expected", name)
+			case "ShowPrivateFields":
+				res = Dir(x, Config{ShowPrivateFields: true})
+			case "DoNotShowPrivateFields":
+				res = Dir(x, Config{ShowPrivateFields: false})
+			}
+
+			path := getDataPath(t, "vars_test.go", tName)
+			dealWithTestData(t, path, res)
+		})
+	}
+}