assert: reduce diff noise

Assertion errors that produce a diff show a diff for identical entries in case one side of the comparison has more object properties than the other one. Those lines are now taken into account and will not show up as diverging lines anymore. Refs: nodejs#22763
BridgeAR · Sep 24, 2018 · 1e6bd03 · 1e6bd03
1 parent de0441f
commit 1e6bd03
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Showing 2 changed files with 50 additions and 29 deletions.
diff --git a/lib/internal/assert.js b/lib/internal/assert.js
@@ -191,29 +191,42 @@ function createErrDiff(actual, expected, operator) {
       res += `\n${green}+${white} ${actualLines[i]}`;
       printedLines++;
     // Lines diverge
-    } else if (actualLines[i] !== expectedLines[i]) {
-      if (cur > 1 && i > 2) {
-        if (cur > 4) {
-          res += `\n${blue}...${white}`;
-          skipped = true;
-        } else if (cur > 3) {
-          res += `\n  ${actualLines[i - 2]}`;
+    } else {
+      const expectedLine = expectedLines[i];
+      let actualLine = actualLines[i];
+      let divergingLines = actualLine !== expectedLine &&
+                           (!actualLine.endsWith(',') ||
+                            actualLine.slice(0, -1) !== expectedLine);
+      if (divergingLines &&
+          expectedLine.endsWith(',') &&
+          expectedLine.slice(0, -1) === actualLine) {
+        divergingLines = false;
+        actualLine += ',';
+      }
+      if (divergingLines) {
+        if (cur > 1 && i > 2) {
+          if (cur > 4) {
+            res += `\n${blue}...${white}`;
+            skipped = true;
+          } else if (cur > 3) {
+            res += `\n  ${actualLines[i - 2]}`;
+            printedLines++;
+          }
+          res += `\n  ${actualLines[i - 1]}`;
+          printedLines++;
+        }
+        lastPos = i;
+        res += `\n${green}+${white} ${actualLine}`;
+        other += `\n${red}-${white} ${expectedLine}`;
+        printedLines += 2;
+      // Lines are identical
+      } else {
+        res += other;
+        other = '';
+        if (cur === 1 || i === 0) {
+          res += `\n  ${actualLine}`;
           printedLines++;
         }
-        res += `\n  ${actualLines[i - 1]}`;
-        printedLines++;
-      }
-      lastPos = i;
-      res += `\n${green}+${white} ${actualLines[i]}`;
-      other += `\n${red}-${white} ${expectedLines[i]}`;
-      printedLines += 2;
-    // Lines are identical
-    } else {
-      res += other;
-      other = '';
-      if (cur === 1 || i === 0) {
-        res += `\n  ${actualLines[i]}`;
-        printedLines++;
       }
     }
     // Inspected object to big (Show ~20 rows max)

diff --git a/test/parallel/test-assert-deep.js b/test/parallel/test-assert-deep.js
@@ -65,9 +65,13 @@ assert.deepEqual(arr, buf);
     () => assert.deepStrictEqual(buf2, buf),
     {
       code: 'ERR_ASSERTION',
-      message: `${defaultMsgStartFull}\n\n` +
-               '  Buffer [Uint8Array] [\n    120,\n    121,\n    122,\n' +
-               '+   10,\n+   prop: 1\n-   10\n  ]'
+      message: `${defaultMsgStartFull} ... Lines skipped\n\n` +
+               '  Buffer [Uint8Array] [\n' +
+               '    120,\n' +
+               '...\n' +
+               '    10,\n' +
+               '+   prop: 1\n' +
+               '  ]'
     }
   );
   assert.deepEqual(buf2, buf);
@@ -80,9 +84,13 @@ assert.deepEqual(arr, buf);
     () => assert.deepStrictEqual(arr, arr2),
     {
       code: 'ERR_ASSERTION',
-      message: `${defaultMsgStartFull}\n\n` +
-               '  Uint8Array [\n    120,\n    121,\n    122,\n' +
-               '+   10\n-   10,\n-   prop: 5\n  ]'
+      message: `${defaultMsgStartFull} ... Lines skipped\n\n` +
+               '  Uint8Array [\n' +
+               '    120,\n' +
+               '...\n' +
+               '    10,\n' +
+               '-   prop: 5\n' +
+               '  ]'
     }
   );
   assert.deepEqual(arr, arr2);
@@ -822,7 +830,7 @@ assert.throws(
     code: 'ERR_ASSERTION',
     name: 'AssertionError [ERR_ASSERTION]',
     message: `${defaultMsgStartFull}\n\n  ` +
-             '{\n+   a: 4\n-   a: 4,\n-   b: true\n  }'
+             '{\n    a: 4,\n-   b: true\n  }'
   });
 assert.throws(
   () => assert.deepStrictEqual(['a'], { 0: 'a' }),
@@ -891,7 +899,7 @@ assert.deepStrictEqual(obj1, obj2);
   assert.throws(
     () => assert.deepStrictEqual(arrProxy, [1, 2, 3]),
     { message: `${defaultMsgStartFull}\n\n` +
-               '  [\n    1,\n+   2\n-   2,\n-   3\n  ]' }
+               '  [\n    1,\n    2,\n-   3\n  ]' }
   );
   util.inspect.defaultOptions = tmp;