Introduce TestWriteDeclsAndStmts

I wanted a way to quickly add example gomacro files as test cases.

This change adds TestWriteDeclsAndStmts that essentially constructs a
new fast interpreter, calls EvalFile and then WriteDeclsToFile.  The
testdata directory is searched for test cases; every test case must have
a .gomacro file, a .go file and optionally a .err file.  The .gomacro
file will be passed to EvalFile and its resulting error will be compared
against contents of any .err file.  Then the contents of the .go file
will be compared to the output of WriteDeclsToStream.  To create a test
just add the .gomacro file and then go test can be called with the
UPDATE_SNAPSHOTS envvar set, e.g.

   UPDATE_SNAPSHOTS=on go test ./cmd -run=TestWriteDeclsAndStmts

This will call EvalFile and WriteDeclsToFile and generate the .go and
.err files.  Note the tests will fail because we are generating, not
testing against the fixture.

The first test added is failing and demonstrates issue #84.

Signed-off-by: Corin Lawson <[email protected]>

cmd/cmd_test.go

@@ -0,0 +1,77 @@
+package cmd_test
+
+import (
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"strings"
+	"testing"
+
+	. "github.com/cosmos72/gomacro/base"
+	. "github.com/cosmos72/gomacro/fast"
+	"github.com/kylelemons/godebug/diff"
+)
+
+func TestWriteDeclsAndStmts(t *testing.T) {
+	testdata, err := ioutil.ReadDir("testdata")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	for _, file := range testdata {
+		if !strings.HasSuffix(file.Name(), ".gomacro") {
+			continue
+		}
+		test := strings.TrimSuffix(file.Name(), ".gomacro")
+		t.Run(test, func(t *testing.T) {
+			gomacroFile := filepath.Join("testdata", test+".gomacro")
+			goFile := filepath.Join("testdata", test+".go")
+			errFile := filepath.Join("testdata", test+".err")
+			ir := New()
+			g := &ir.Comp.Globals
+			g.Options |= OptCollectDeclarations | OptCollectStatements
+
+			comments, got := ir.EvalFile(gomacroFile)
+
+			if os.Getenv("UPDATE_SNAPSHOTS") != "" {
+				if got != nil {
+					if err := ioutil.WriteFile(errFile, []byte(got.Error()), 0644); err != nil {
+						t.Fatal(err)
+					}
+				}
+
+				g.WriteDeclsToFile(goFile, comments)
+
+				t.Fail() // Test not performed
+			} else {
+				buf, err := ioutil.ReadFile(errFile)
+				if os.IsNotExist(err) {
+					if got != nil {
+						t.Errorf("EvalFile returned an error: %q", got)
+					}
+				} else if err == nil {
+					if got == nil {
+						t.Errorf("EvalFile didn't return an expected error:\nwant %q", string(buf))
+					} else if string(buf) != got.Error() {
+						t.Errorf("EvalFile returned an unexpected error:\nwant %q;\n got %q", string(buf), got)
+					}
+				} else {
+					t.Fatal(err)
+				}
+
+				if buf, err = ioutil.ReadFile(goFile); err != nil {
+					if os.IsNotExist(err) {
+						t.Fatalf("%s, try setting UPDATE_SNAPSHOTS=on", err)
+					}
+					t.Fatal(err)
+				}
+				out := &strings.Builder{}
+				out.WriteString(comments)
+				g.WriteDeclsToStream(out)
+				if diff := diff.Diff(string(buf), out.String()); diff != "" {
+					t.Errorf("EvalFile produced unexpected AST (lines starting with '-' are missing, '+' lines are superfluous):\n%s", diff)
+				}
+			}
+		})
+	}
+}

cmd/testdata/type.go

@@ -0,0 +1,3 @@
+package main
+
+type Name struct{}

cmd/testdata/type.gomacro

@@ -0,0 +1,7 @@
+:macro make() interface{} {
+	return ~"{
+		type Name struct{}
+	}
+}
+
+make

go.mod

@@ -3,6 +3,7 @@ module github.com/cosmos72/gomacro
 go 1.9
 
 require (
+	github.com/kylelemons/godebug v1.1.0
 	github.com/mattn/go-runewidth v0.0.7
 	github.com/peterh/liner v1.1.0
 	golang.org/x/tools v0.0.0-20191206204035-259af5ff87bd

go.sum

@@ -1,3 +1,5 @@
+github.com/kylelemons/godebug v1.1.0 h1:RPNrshWIDI6G2gRW9EHilWtl7Z6Sb1BR0xunSBf0SNc=
+github.com/kylelemons/godebug v1.1.0/go.mod h1:9/0rRGxNHcop5bhtWyNeEfOS8JIWk580+fNqagV/RAw=
 github.com/mattn/go-runewidth v0.0.3/go.mod h1:LwmH8dsx7+W8Uxz3IHJYH5QSwggIsqBzpuz5H//U1FU=
 github.com/mattn/go-runewidth v0.0.7 h1:Ei8KR0497xHyKJPAv59M1dkC+rOZCMBJ+t3fZ+twI54=
 github.com/mattn/go-runewidth v0.0.7/go.mod h1:H031xJmbD/WCDINGzjvQ9THkh0rPKHF+m2gUSrubnMI=