Better testify usage (#54)

* Use assert.NoError instead of assert.Nil

This gives nicer error messages.

* Swap arguments to assert.Equal

The expectation comes first. Otherwise, error messages will be
misleading.

An example:

=== RUN   TestDeleteWithIncorrectRepoForDeleteCaches
Error: authentication token not found for host github.com
    delete_test.go:56:
                Error Trace:    /build/source/cmd/delete_test.go:56
                Error:          Should be true
                Test:           TestDeleteWithIncorrectRepoForDeleteCaches
                Messages:       1 unmatched mocks: https://api.github.com/repos/testOrg/testRepo/actions/caches?key=cacheName
    delete_test.go:59:
                Error Trace:    /build/source/cmd/delete_test.go:59
                Error:          Not equal:
                                expected: "authentication token not found for host github.com"
                                actual  : "The given repo does not exist."

                                Diff:
                                --- Expected
                                +++ Actual
                                @@ -1 +1 @@
                                -authentication token not found for host github.com
                                +The given repo does not exist.
                Test:           TestDeleteWithIncorrectRepoForDeleteCaches
--- FAIL: TestDeleteWithIncorrectRepoForDeleteCaches (0.00s)

* Use assert.Error instead of assert.NotNil

This gives nicer error messages.

* Use assert.ErrorAs and assert.ErrorContains

This simplifies the assertions and potentially gives better error
messages.

* Use require instead of assert and use assert.NotNil as guard

This is to prevent panics in tests, when things get accessed which
shouldn't be nil.

cmd/delete_test.go

@@ -1,9 +1,6 @@
 package cmd
 
 import (
-	"errors"
-	"fmt"
-	"reflect"
 	"testing"
 
 	"github.com/actions/gh-actions-cache/internal"
@@ -19,8 +16,7 @@ func TestDeleteWithIncorrectArguments(t *testing.T) {
 	cmd.SetArgs([]string{})
 	err := cmd.Execute()
 
-	assert.NotNil(t, err)
-	assert.Equal(t, err, fmt.Errorf("accepts 1 arg(s), received 0"))
+	assert.ErrorContains(t, err, "accepts 1 arg(s), received 0")
 	assert.True(t, gock.IsDone(), internal.PrintPendingMocks(gock.Pending()))
 }
 
@@ -31,8 +27,7 @@ func TestDeleteWithIncorrectRepo(t *testing.T) {
 	cmd.SetArgs([]string{"--repo", "testOrg/testRepo/123/123", "cacheName"})
 	err := cmd.Execute()
 
-	assert.NotNil(t, err)
-	assert.Equal(t, err, fmt.Errorf("expected the \"[HOST/]OWNER/REPO\" format, got \"testOrg/testRepo/123/123\""))
+	assert.ErrorContains(t, err, "expected the \"[HOST/]OWNER/REPO\" format, got \"testOrg/testRepo/123/123\"")
 	assert.True(t, gock.IsDone(), internal.PrintPendingMocks(gock.Pending()))
 }
 
@@ -52,11 +47,11 @@ func TestDeleteWithIncorrectRepoForDeleteCaches(t *testing.T) {
 	cmd.SetArgs([]string{"--repo", "testOrg/testRepo", "cacheName"})
 	err := cmd.Execute()
 
-	assert.NotNil(t, err)
-	assert.True(t, gock.IsDone(), internal.PrintPendingMocks(gock.Pending()))
 	var customError types.HandledError
-	errors.As(err, &customError)
-	assert.Equal(t, customError.Message, "The given repo does not exist.")
+	if assert.ErrorAs(t, err, &customError) {
+		assert.Equal(t, "The given repo does not exist.", customError.Message)
+	}
+	assert.True(t, gock.IsDone(), internal.PrintPendingMocks(gock.Pending()))
 }
 
 func TestDeleteSuccessWithConfirmFlagProvided(t *testing.T) {
@@ -85,7 +80,7 @@ func TestDeleteSuccessWithConfirmFlagProvided(t *testing.T) {
 	cmd.SetArgs([]string{"--repo", "testOrg/testRepo", "2022-06-29T13:33:49", "--confirm"})
 	err := cmd.Execute()
 
-	assert.Nil(t, err)
+	assert.NoError(t, err)
 	assert.True(t, gock.IsDone(), internal.PrintPendingMocks(gock.Pending()))
 }
 
@@ -116,7 +111,7 @@ func TestDeleteFailureWhileTakingUserInput(t *testing.T) {
 	cmd.SetArgs([]string{"--repo", "testOrg/testRepo", "2022-06-29T13:33:49"})
 	err := cmd.Execute()
 
-	assert.NotNil(t, err)
+	assert.Error(t, err)
 	assert.True(t, gock.IsDone(), internal.PrintPendingMocks(gock.Pending()))
 }
 
@@ -135,13 +130,10 @@ func TestDeleteWithUnauthorizedRequestForDeleteCaches(t *testing.T) {
 	cmd.SetArgs([]string{"--repo", "testOrg/testRepo", "cacheKey", "--confirm"})
 	err := cmd.Execute()
 
-	assert.NotNil(t, err)
-	assert.Equal(t, reflect.TypeOf(err), reflect.TypeOf(types.HandledError{}))
-
 	var customError types.HandledError
-	errors.As(err, &customError)
-	assert.Equal(t, customError.Message, "Must have admin rights to Repository.")
-
+	if assert.ErrorAs(t, err, &customError) {
+		assert.Equal(t, "Must have admin rights to Repository.", customError.Message)
+	}
 	assert.True(t, gock.IsDone(), internal.PrintPendingMocks(gock.Pending()))
 }
 
@@ -160,12 +152,9 @@ func TestDeleteWithInternalServerErrorForDeleteCaches(t *testing.T) {
 	cmd.SetArgs([]string{"--repo", "testOrg/testRepo", "cacheKey", "--confirm"})
 	err := cmd.Execute()
 
-	assert.NotNil(t, err)
-	assert.Equal(t, reflect.TypeOf(err), reflect.TypeOf(types.HandledError{}))
-
 	var customError types.HandledError
-	errors.As(err, &customError)
-	assert.Equal(t, customError.Message, "We could not process your request due to internal error.")
-
+	if assert.ErrorAs(t, err, &customError) {
+		assert.Equal(t, "We could not process your request due to internal error.", customError.Message)
+	}
 	assert.True(t, gock.IsDone(), internal.PrintPendingMocks(gock.Pending()))
 }