log: add testing for context logger

Signed-off-by: Stephen J Day <stephen.day@docker.com>

log/context_test.go

@@ -0,0 +1,41 @@
+package log
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"golang.org/x/net/context"
+)
+
+func TestLoggerContext(t *testing.T) {
+	ctx := context.Background()
+	assert.Equal(t, GetLogger(ctx), L)      // should be same as L variable
+	assert.Equal(t, G(ctx), GetLogger(ctx)) // these should be the same.
+
+	ctx = WithLogger(ctx, G(ctx).WithField("test", "one"))
+	assert.Equal(t, GetLogger(ctx).Data["test"], "one")
+	assert.Equal(t, G(ctx), GetLogger(ctx)) // these should be the same.
+}
+
+func TestModuleContext(t *testing.T) {
+	ctx := context.Background()
+	assert.Equal(t, GetModulePath(ctx), "")
+
+	ctx = WithModule(ctx, "a") // basic behavior
+	assert.Equal(t, GetModulePath(ctx), "a")
+	logger := GetLogger(ctx)
+	assert.Equal(t, logger.Data["module"], "a")
+
+	parent, ctx := ctx, WithModule(ctx, "a")
+	assert.Equal(t, ctx, parent) // should be a no-op
+	assert.Equal(t, GetModulePath(ctx), "a")
+	assert.Equal(t, GetLogger(ctx).Data["module"], "a")
+
+	ctx = WithModule(ctx, "b") // new module
+	assert.Equal(t, GetModulePath(ctx), "a/b")
+	assert.Equal(t, GetLogger(ctx).Data["module"], "a/b")
+
+	ctx = WithModule(ctx, "c") // new module
+	assert.Equal(t, GetModulePath(ctx), "a/b/c")
+	assert.Equal(t, GetLogger(ctx).Data["module"], "a/b/c")
+}