terraform: add variables to Interpolator value

Fixes #10412

The context wasn't properly adding variable values to the Interpolator
instance which made it so that the `console` command couldn't access
variables set via tfvars and the CLI.

This also adds better test coverage in command itself for this.

command/command_test.go

@@ -2,6 +2,7 @@ package command
 
 import (
 	"flag"
+	"io"
 	"io/ioutil"
 	"log"
 	"os"
@@ -336,3 +337,67 @@ func testFixCwd(t *testing.T, tmp, cwd string) {
 		t.Fatalf("err: %v", err)
 	}
 }
+
+// testStdinPipe changes os.Stdin to be a pipe that sends the data from
+// the reader before closing the pipe.
+//
+// The returned function should be deferred to properly clean up and restore
+// the original stdin.
+func testStdinPipe(t *testing.T, src io.Reader) func() {
+	r, w, err := os.Pipe()
+	if err != nil {
+		t.Fatalf("err: %s", err)
+	}
+
+	// Modify stdin to point to our new pipe
+	old := os.Stdin
+	os.Stdin = r
+
+	// Copy the data from the reader to the pipe
+	go func() {
+		defer w.Close()
+		io.Copy(w, src)
+	}()
+
+	return func() {
+		// Close our read end
+		r.Close()
+
+		// Reset stdin
+		os.Stdin = old
+	}
+}
+
+// Modify os.Stdout to write to the given buffer. Note that this is generally
+// not useful since the commands are configured to write to a cli.Ui, not
+// Stdout directly. Commands like `console` though use the raw stdout.
+func testStdoutCapture(t *testing.T, dst io.Writer) func() {
+	r, w, err := os.Pipe()
+	if err != nil {
+		t.Fatalf("err: %s", err)
+	}
+
+	// Modify stdout
+	old := os.Stdout
+	os.Stdout = w
+
+	// Copy
+	doneCh := make(chan struct{})
+	go func() {
+		defer close(doneCh)
+		defer r.Close()
+		io.Copy(dst, r)
+	}()
+
+	return func() {
+		// Close the writer end of the pipe
+		w.Sync()
+		w.Close()
+
+		// Reset stdout
+		os.Stdout = old
+
+		// Wait for the data copy to complete to avoid a race reading data
+		<-doneCh
+	}
+}

command/console_test.go

@@ -1,6 +1,86 @@
 package command
 
+import (
+	"bytes"
+	"io/ioutil"
+	"path/filepath"
+	"strings"
+	"testing"
+
+	"github.com/mitchellh/cli"
+)
+
 // ConsoleCommand is tested primarily with tests in the "repl" package.
 // It is not tested here because the Console uses a readline-like library
 // that takes over stdin/stdout. It is difficult to test directly. The
 // core logic is tested in "repl"
+//
+// This file still contains some tests using the stdin-based input.
+
+func TestConsole_basic(t *testing.T) {
+	tmp, cwd := testCwd(t)
+	defer testFixCwd(t, tmp, cwd)
+
+	p := testProvider()
+	ui := new(cli.MockUi)
+	c := &ConsoleCommand{
+		Meta: Meta{
+			ContextOpts: testCtxConfig(p),
+			Ui:          ui,
+		},
+	}
+
+	var output bytes.Buffer
+	defer testStdinPipe(t, strings.NewReader("1+5\n"))()
+	outCloser := testStdoutCapture(t, &output)
+
+	args := []string{}
+	code := c.Run(args)
+	outCloser()
+	if code != 0 {
+		t.Fatalf("bad: %d\n\n%s", code, ui.ErrorWriter.String())
+	}
+
+	actual := output.String()
+	if actual != "6\n" {
+		t.Fatalf("bad: %q", actual)
+	}
+}
+
+func TestConsole_tfvars(t *testing.T) {
+	tmp, cwd := testCwd(t)
+	defer testFixCwd(t, tmp, cwd)
+
+	// Write a terraform.tvars
+	varFilePath := filepath.Join(tmp, "terraform.tfvars")
+	if err := ioutil.WriteFile(varFilePath, []byte(applyVarFile), 0644); err != nil {
+		t.Fatalf("err: %s", err)
+	}
+
+	p := testProvider()
+	ui := new(cli.MockUi)
+	c := &ConsoleCommand{
+		Meta: Meta{
+			ContextOpts: testCtxConfig(p),
+			Ui:          ui,
+		},
+	}
+
+	var output bytes.Buffer
+	defer testStdinPipe(t, strings.NewReader("var.foo\n"))()
+	outCloser := testStdoutCapture(t, &output)
+
+	args := []string{
+		testFixturePath("apply-vars"),
+	}
+	code := c.Run(args)
+	outCloser()
+	if code != 0 {
+		t.Fatalf("bad: %d\n\n%s", code, ui.ErrorWriter.String())
+	}
+
+	actual := output.String()
+	if actual != "bar\n" {
+		t.Fatalf("bad: %q", actual)
+	}
+}

terraform/context.go

@@ -246,7 +246,7 @@ func (c *Context) Interpolater() *Interpolater {
 		Module:             c.module,
 		State:              c.state.DeepCopy(),
 		StateLock:          &stateLock,
-		VariableValues:     map[string]interface{}{},
+		VariableValues:     c.variables,
 		VariableValuesLock: &varLock,
 	}
 }