cli/command/image/build: fix linting, add sub-tests

- fix minor linting issues (unhandled errors)
- rename vars to prevent shadowing
- use sub-tests for tests that already prepared for it

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

cli/command/image/build/context.go

@@ -80,7 +80,7 @@ func ValidateContextDirectory(srcPath string, excludes []string) error {
 			if err != nil && os.IsPermission(err) {
 				return fmt.Errorf("no permission to read from '%s'", filePath)
 			}
-			currentFile.Close()
+			_ = currentFile.Close()
 		}
 		return nil
 	})
@@ -97,10 +97,10 @@ func filepathMatches(matcher *patternmatcher.PatternMatcher, file string) (bool,
 
 // DetectArchiveReader detects whether the input stream is an archive or a
 // Dockerfile and returns a buffered version of input, safe to consume in lieu
-// of input. If an archive is detected, isArchive is set to true, and to false
+// of input. If an archive is detected, ok is set to true, and to false
 // otherwise, in which case it is safe to assume input represents the contents
 // of a Dockerfile.
-func DetectArchiveReader(input io.ReadCloser) (rc io.ReadCloser, isArchive bool, err error) {
+func DetectArchiveReader(input io.ReadCloser) (rc io.ReadCloser, ok bool, err error) {
 	buf := bufio.NewReader(input)
 
 	magic, err := buf.Peek(archiveHeaderSize * 2)
@@ -141,12 +141,12 @@ func WriteTempDockerfile(rc io.ReadCloser) (dockerfileDir string, err error) {
 // Dockerfile or tar archive. Returns a tar archive used as a context and a
 // path to the Dockerfile inside the tar.
 func GetContextFromReader(rc io.ReadCloser, dockerfileName string) (out io.ReadCloser, relDockerfile string, err error) {
-	rc, isArchive, err := DetectArchiveReader(rc)
+	rc, ok, err := DetectArchiveReader(rc)
 	if err != nil {
 		return nil, "", err
 	}
 
-	if isArchive {
+	if ok {
 		return rc, dockerfileName, nil
 	}
 
@@ -171,7 +171,7 @@ func GetContextFromReader(rc io.ReadCloser, dockerfileName string) (out io.ReadC
 
 	return newReadCloserWrapper(tarArchive, func() error {
 		err := tarArchive.Close()
-		os.RemoveAll(dockerfileDir)
+		_ = os.RemoveAll(dockerfileDir)
 		return err
 	}), DefaultDockerfileName, nil
 }
@@ -242,7 +242,7 @@ func getWithStatusError(url string) (resp *http.Response, err error) {
 	}
 	msg := fmt.Sprintf("failed to GET %s with status %s", url, resp.Status)
 	body, err := io.ReadAll(resp.Body)
-	resp.Body.Close()
+	_ = resp.Body.Close()
 	if err != nil {
 		return nil, fmt.Errorf("%s: error reading body: %w", msg, err)
 	}
@@ -374,7 +374,7 @@ func isUNC(path string) bool {
 // the relative path to the dockerfile in the context.
 func AddDockerfileToBuildContext(dockerfileCtx io.ReadCloser, buildCtx io.ReadCloser) (io.ReadCloser, string, error) {
 	file, err := io.ReadAll(dockerfileCtx)
-	dockerfileCtx.Close()
+	_ = dockerfileCtx.Close()
 	if err != nil {
 		return nil, "", err
 	}
@@ -438,17 +438,19 @@ func Compress(buildCtx io.ReadCloser) (io.ReadCloser, error) {
 	go func() {
 		compressWriter, err := compression.CompressStream(pipeWriter, archive.Gzip)
 		if err != nil {
-			pipeWriter.CloseWithError(err)
+			_ = pipeWriter.CloseWithError(err)
 		}
-		defer buildCtx.Close()
+		defer func() {
+			_ = buildCtx.Close()
+		}()
 
 		if _, err := io.Copy(compressWriter, buildCtx); err != nil {
-			pipeWriter.CloseWithError(fmt.Errorf("failed to compress context: %w", err))
-			compressWriter.Close()
+			_ = pipeWriter.CloseWithError(fmt.Errorf("failed to compress context: %w", err))
+			_ = compressWriter.Close()
 			return
 		}
-		compressWriter.Close()
-		pipeWriter.Close()
+		_ = compressWriter.Close()
+		_ = pipeWriter.Close()
 	}()
 
 	return pipeReader, nil

cli/command/image/build/context_test.go

@@ -135,7 +135,7 @@ func TestGetContextFromReaderString(t *testing.T) {
 	}
 
 	buff := new(bytes.Buffer)
-	buff.ReadFrom(tarReader)
+	_, _ = buff.ReadFrom(tarReader)
 	contents := buff.String()
 
 	_, err = tarReader.Next()
@@ -182,7 +182,7 @@ func TestGetContextFromReaderTar(t *testing.T) {
 	}
 
 	buff := new(bytes.Buffer)
-	buff.ReadFrom(tarReader)
+	_, _ = buff.ReadFrom(tarReader)
 	contents := buff.String()
 
 	_, err = tarReader.Next()
@@ -263,7 +263,7 @@ func chdir(t *testing.T, dir string) {
 }
 
 func TestIsArchive(t *testing.T) {
-	testcases := []struct {
+	tests := []struct {
 		doc      string
 		header   []byte
 		expected bool
@@ -289,13 +289,15 @@ func TestIsArchive(t *testing.T) {
 			expected: false,
 		},
 	}
-	for _, testcase := range testcases {
-		assert.Check(t, is.Equal(testcase.expected, IsArchive(testcase.header)), testcase.doc)
+	for _, tc := range tests {
+		t.Run(tc.doc, func(t *testing.T) {
+			assert.Check(t, is.Equal(tc.expected, IsArchive(tc.header)), tc.doc)
+		})
 	}
 }
 
 func TestDetectArchiveReader(t *testing.T) {
-	testcases := []struct {
+	tests := []struct {
 		file     string
 		desc     string
 		expected bool
@@ -316,14 +318,18 @@ func TestDetectArchiveReader(t *testing.T) {
 			expected: false,
 		},
 	}
-	for _, testcase := range testcases {
-		content, err := os.Open(testcase.file)
-		assert.NilError(t, err)
-		defer content.Close()
+	for _, tc := range tests {
+		t.Run(tc.desc, func(t *testing.T) {
+			content, err := os.Open(tc.file)
+			assert.NilError(t, err)
+			defer func() {
+				_ = content.Close()
+			}()
 
-		_, isArchive, err := DetectArchiveReader(content)
-		assert.NilError(t, err)
-		assert.Check(t, is.Equal(testcase.expected, isArchive), testcase.file)
+			_, isArchive, err := DetectArchiveReader(content)
+			assert.NilError(t, err)
+			assert.Check(t, is.Equal(tc.expected, isArchive), tc.file)
+		})
 	}
 }
 

cli/command/image/build/dockerignore.go

@@ -21,7 +21,9 @@ func ReadDockerignore(contextDir string) ([]string, error) {
 	case err != nil:
 		return nil, err
 	}
-	defer f.Close()
+	defer func() {
+		_ = f.Close()
+	}()
 
 	patterns, err := ignorefile.ReadAll(f)
 	if err != nil {