Introduce tflogtest and tfsdklogtest packages (#62)

Reference: #61

.changelog/62.txt

@@ -0,0 +1,7 @@
+```release-note:feature
+Added `tflogtest` package, which provides functionality for unit testing of provider logging
+```
+
+```release-note:feature
+Added `tfsdklogtest` package, which provides functionality for unit testing of SDK logging
+```

internal/loggertest/json_decode.go

@@ -8,11 +8,12 @@ import (
 
 func MultilineJSONDecode(data io.Reader) ([]map[string]interface{}, error) {
 	var result []map[string]interface{}
-	var entry map[string]interface{}
 
 	dec := json.NewDecoder(data)
 
 	for {
+		var entry map[string]interface{}
+
 		err := dec.Decode(&entry)
 
 		if err == io.EOF {

tflogtest/doc.go

@@ -0,0 +1,3 @@
+// Package tflogtest provides functionality for unit testing of provider
+// logging.
+package tflogtest

tflogtest/json_decode.go

@@ -0,0 +1,13 @@
+package tflogtest
+
+import (
+	"io"
+
+	"github.com/hashicorp/terraform-plugin-log/internal/loggertest"
+)
+
+// MultilineJSONDecode supports decoding the output of a JSON logger into a
+// slice of maps, with each element representing a log entry.
+func MultilineJSONDecode(data io.Reader) ([]map[string]interface{}, error) {
+	return loggertest.MultilineJSONDecode(data)
+}

tflogtest/json_decode_example_test.go

@@ -0,0 +1,38 @@
+package tflogtest
+
+import (
+	"bytes"
+	"context"
+	"fmt"
+
+	"github.com/hashicorp/terraform-plugin-log/tflog"
+)
+
+func ExampleMultilineJSONDecode() {
+	var output bytes.Buffer
+
+	ctx := RootLogger(context.Background(), &output)
+
+	// Root provider logger is now available for usage, such as writing
+	// entries, calling With(), or calling NewSubsystem().
+	tflog.Trace(ctx, "entry 1")
+	tflog.Trace(ctx, "entry 2")
+
+	entries, err := MultilineJSONDecode(&output)
+
+	if err != nil {
+		// Typical unit testing would call t.Fatalf() here.
+		fmt.Printf("unable to read multiple line JSON: %s", err)
+	}
+
+	// Entries can be checked via go-cmp's cmp.Diff() or other testing methods.
+	// This example outputs them to stdout in an explicitly formatted string,
+	// which would not be expected in typical unit testing.
+	for _, entry := range entries {
+		fmt.Printf("@message: %s\n", entry["@message"])
+	}
+
+	// Output:
+	// @message: entry 1
+	// @message: entry 2
+}

tflogtest/root_logger.go

@@ -0,0 +1,21 @@
+package tflogtest
+
+import (
+	"context"
+	"io"
+
+	"github.com/hashicorp/terraform-plugin-log/internal/loggertest"
+)
+
+// RootLogger returns a context containing a provider root logger suitable for
+// unit testing that is:
+//
+//    - Written to the given io.Writer, such as a bytes.Buffer.
+//    - Written with JSON output, that can be decoded with MultilineJSONDecode.
+//    - Log level set to TRACE.
+//    - Without location/caller information in log entries.
+//    - Without timestamps in log entries.
+//
+func RootLogger(ctx context.Context, output io.Writer) context.Context {
+	return loggertest.ProviderRoot(ctx, output)
+}

tflogtest/root_logger_example_test.go

@@ -0,0 +1,27 @@
+package tflogtest
+
+import (
+	"bytes"
+	"context"
+	"fmt"
+
+	"github.com/hashicorp/terraform-plugin-log/tflog"
+)
+
+func ExampleRootLogger() {
+	var output bytes.Buffer
+
+	ctx := RootLogger(context.Background(), &output)
+
+	// Root provider logger is now available for usage, such as writing
+	// entries, calling With(), or calling NewSubsystem().
+	tflog.Trace(ctx, "hello, world", map[string]interface{}{
+		"foo":    123,
+		"colors": []string{"red", "blue", "green"},
+	})
+
+	fmt.Println(output.String())
+
+	// Output:
+	// {"@level":"trace","@message":"hello, world","@module":"provider","colors":["red","blue","green"],"foo":123}
+}

tfsdklogtest/doc.go

@@ -0,0 +1,3 @@
+// Package tfsdklogtest provides functionality for unit testing of SDK
+// logging. Provider developers should use the tflogtest package.
+package tfsdklogtest

tfsdklogtest/json_decode.go

@@ -0,0 +1,13 @@
+package tfsdklogtest
+
+import (
+	"io"
+
+	"github.com/hashicorp/terraform-plugin-log/internal/loggertest"
+)
+
+// MultilineJSONDecode supports decoding the output of a JSON logger into a
+// slice of maps, with each element representing a log entry.
+func MultilineJSONDecode(data io.Reader) ([]map[string]interface{}, error) {
+	return loggertest.MultilineJSONDecode(data)
+}

tfsdklogtest/json_decode_example_test.go

@@ -0,0 +1,38 @@
+package tfsdklogtest
+
+import (
+	"bytes"
+	"context"
+	"fmt"
+
+	"github.com/hashicorp/terraform-plugin-log/tfsdklog"
+)
+
+func ExampleMultilineJSONDecode() {
+	var output bytes.Buffer
+
+	ctx := RootLogger(context.Background(), &output)
+
+	// Root SDK logger is now available for usage, such as writing entries,
+	// calling With(), or calling NewSubsystem().
+	tfsdklog.Trace(ctx, "entry 1")
+	tfsdklog.Trace(ctx, "entry 2")
+
+	entries, err := MultilineJSONDecode(&output)
+
+	if err != nil {
+		// Typical unit testing would call t.Fatalf() here.
+		fmt.Printf("unable to read multiple line JSON: %s", err)
+	}
+
+	// Entries can be checked via go-cmp's cmp.Diff() or other testing methods.
+	// This example outputs them to stdout in an explicitly formatted string,
+	// which would not be expected in typical unit testing.
+	for _, entry := range entries {
+		fmt.Printf("@message: %s\n", entry["@message"])
+	}
+
+	// Output:
+	// @message: entry 1
+	// @message: entry 2
+}

tfsdklogtest/root_logger.go

@@ -0,0 +1,21 @@
+package tfsdklogtest
+
+import (
+	"context"
+	"io"
+
+	"github.com/hashicorp/terraform-plugin-log/internal/loggertest"
+)
+
+// RootLogger returns a context containing a SDK root logger suitable for unit
+// testing that is:
+//
+//    - Written to the given io.Writer, such as a bytes.Buffer.
+//    - Written with JSON output, that can be decoded with MultilineJSONDecode.
+//    - Log level set to TRACE.
+//    - Without location/caller information in log entries.
+//    - Without timestamps in log entries.
+//
+func RootLogger(ctx context.Context, output io.Writer) context.Context {
+	return loggertest.SDKRoot(ctx, output)
+}

tfsdklogtest/root_logger_example_test.go

@@ -0,0 +1,27 @@
+package tfsdklogtest
+
+import (
+	"bytes"
+	"context"
+	"fmt"
+
+	"github.com/hashicorp/terraform-plugin-log/tfsdklog"
+)
+
+func ExampleRootLogger() {
+	var output bytes.Buffer
+
+	ctx := RootLogger(context.Background(), &output)
+
+	// Root SDK logger is now available for usage, such as writing entries,
+	// calling With(), or calling NewSubsystem().
+	tfsdklog.Trace(ctx, "hello, world", map[string]interface{}{
+		"foo":    123,
+		"colors": []string{"red", "blue", "green"},
+	})
+
+	fmt.Println(output.String())
+
+	// Output:
+	// {"@level":"trace","@message":"hello, world","@module":"sdk","colors":["red","blue","green"],"foo":123}
+}