Fix #66 Change formatter to not create unnecessary edits

The formatter should not create edits on lines that are already indented correctly. For example, if we expect a tab on a line and there is already a tab then no edits should be created even if the creation of such an edit is essentially a no-op. Signed-off-by: Remy Suen <[email protected]>
rcjsuen · Dec 25, 2019 · e3edce2 · e3edce2
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diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -5,6 +5,7 @@ All notable changes to this project will be documented in this file.
 ### Fixed
 - do not append newline when printing out the output of `dockerfile-utils format` to the console ([#63](https://github.com/rcjsuen/dockerfile-utils/issues/63))
 - allow paths to be quoted in WORKDIRs ([#67](https://github.com/rcjsuen/dockerfile-utils/issues/67))
+- do not calculate edits for lines that are already formatted correctly ([#66](https://github.com/rcjsuen/dockerfile-utils/issues/66))
 
 ## [0.0.13] - 2019-05-22
 ### Added

diff --git a/src/dockerFormatter.ts b/src/dockerFormatter.ts
@@ -150,9 +150,17 @@ export class DockerFormatter {
                         // process the next line
                         continue lineCheck;
                     default:
-                        // non-whitespace encountered
-                        if (i !== startOffset || indentedLines[line]) {
-                            let edit = this.createFormattingEdit(document, startOffset, i, indentedLines[line], indentation);
+                        // found a line that should be indented
+                        if (indentedLines[line]) {
+                            const originalIndentation = document.getText().substring(startOffset, i);
+                            // change the indentation if it's not what we expect
+                            if (originalIndentation !== indentation) {
+                                const edit = this.createFormattingEdit(document, startOffset, i, indentedLines[line], indentation);
+                                edits.push(edit);
+                            }
+                        } else if (i !== startOffset) {
+                            // non-whitespace character encountered, realign
+                            const edit = this.createFormattingEdit(document, startOffset, i, indentedLines[line], indentation);
                             edits.push(edit);
                         }
                         // process the next line

diff --git a/test/dockerFormatter.test.ts b/test/dockerFormatter.test.ts
@@ -144,6 +144,12 @@ describe("Dockerfile formatter", function() {
         });
 
         describe("newline escaped tabbing", function() {
+            it("correctly formatted", function() {
+                let document = createDocument("EXPOSE 8081\\\n\t8082");
+                let edits = formatDocument(document);
+                assert.equal(edits.length, 0);
+            });
+
             it("single newline", function() {
                 let document = createDocument("EXPOSE 8081\\\n8082");
                 let edits = formatDocument(document);