From bc8b26d5f80a2bff2c94fa5d5570b06c965be7b4 Mon Sep 17 00:00:00 2001
From: Chris Cuellar <58723+ChrisC@users.noreply.github.com>
Date: Tue, 28 Nov 2023 22:12:28 -0800
Subject: [PATCH 1/7] set log message default to quiet

---
 scripts/update-bcd.ts | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/scripts/update-bcd.ts b/scripts/update-bcd.ts
index 31314231f..a406fa603 100644
--- a/scripts/update-bcd.ts
+++ b/scripts/update-bcd.ts
@@ -363,7 +363,12 @@ const reason = (
   message: ReasonMessageFactory,
   args: Omit<Reason, "message"> = {},
 ): ReasonFactory => {
-  return (value) => ({message: message(value), skip: true, ...args});
+  return (value) => ({
+    message: message(value),
+    skip: true,
+    quiet: true,
+    ...args,
+  });
 };
 
 const isReasonFactory = (
@@ -975,9 +980,9 @@ export const update = (
       if (!statements?.length) {
         return reason(
           ({browser, path}) =>
-            `${path} skipped for ${browser}: no reason identified`,
+            `${path} skipped for ${browser}: no known reason identified. Possible intervention required.`,
           {
-            quiet: true,
+            quiet: false,
           },
         );
       }

From e4944b9db88c8fd03d72e48eda24ad2ce79662ef Mon Sep 17 00:00:00 2001
From: Chris Cuellar <58723+ChrisC@users.noreply.github.com>
Date: Tue, 28 Nov 2023 22:20:52 -0800
Subject: [PATCH 2/7] adds helper to detect contradictions

---
 scripts/update-bcd.test.ts | 120 +++++++++++++++++++++++++++++++++++++
 scripts/update-bcd.ts      |  66 +++++++++++++++++++-
 2 files changed, 183 insertions(+), 3 deletions(-)

diff --git a/scripts/update-bcd.test.ts b/scripts/update-bcd.test.ts
index 891381c40..f1c9b8f88 100644
--- a/scripts/update-bcd.test.ts
+++ b/scripts/update-bcd.test.ts
@@ -19,6 +19,7 @@ import {
   findEntry,
   getSupportMap,
   getSupportMatrix,
+  hasSupportMatrixContradictions,
   inferSupportStatements,
   splitRange,
   update,
@@ -821,6 +822,125 @@ describe("BCD updater", () => {
     });
   });
 
+  describe("hasSupportMatrixContradictions", () => {
+    it("detects contradictions with nonexistent support statements", () => {
+      assert.isTrue(
+        hasSupportMatrixContradictions(new Map([["80", true]]), {
+          version_added: null,
+        }),
+      );
+
+      assert.isTrue(
+        hasSupportMatrixContradictions(new Map([["80", true]]), undefined),
+      );
+    });
+
+    it("skips null support claims", () => {
+      assert.isFalse(
+        hasSupportMatrixContradictions(new Map([["80", null]]), {
+          version_added: "≤80",
+        }),
+      );
+
+      assert.isFalse(
+        hasSupportMatrixContradictions(
+          new Map([
+            ["79", false],
+            ["80", true],
+            ["81", true],
+            ["82", null],
+          ]),
+          {
+            version_added: "≤80",
+          },
+        ),
+        "skips new null test result",
+      );
+    });
+
+    it("detects contradictions in statements with boolean values", () => {
+      assert.isFalse(
+        hasSupportMatrixContradictions(new Map([["80", false]]), {
+          version_added: false,
+        }),
+        "skips generic false statements",
+      );
+      // TODO: verify this is the result that we want
+      assert.isFalse(
+        hasSupportMatrixContradictions(new Map([["80", true]]), {
+          version_added: true,
+        }),
+        "skips generic true statements",
+      );
+
+      assert.isTrue(
+        hasSupportMatrixContradictions(
+          new Map([
+            ["80", false],
+            ["81", true],
+          ]),
+          {version_added: false},
+        ),
+      );
+    });
+
+    it("detects contradictions in statements with string values", () => {
+      assert.isTrue(
+        hasSupportMatrixContradictions(
+          new Map([
+            ["79", false],
+            ["80", false],
+            ["81", true],
+          ]),
+          {
+            version_added: "≤80",
+          },
+        ),
+      );
+
+      assert.isFalse(
+        hasSupportMatrixContradictions(
+          new Map([
+            ["79", false],
+            ["80", false],
+            ["81", true],
+          ]),
+          {
+            version_added: "81",
+          },
+        ),
+      );
+
+      assert.isFalse(
+        hasSupportMatrixContradictions(
+          new Map([
+            ["79", false],
+            ["80", true],
+            ["81", true],
+          ]),
+          {
+            version_added: "≤80",
+          },
+        ),
+      );
+
+      assert.isTrue(
+        hasSupportMatrixContradictions(
+          new Map([
+            ["79", false],
+            ["80", true],
+            ["81", true],
+            ["82", false],
+          ]),
+          {
+            version_added: "≤80",
+          },
+        ),
+        "detects possible support removal",
+      );
+    });
+  });
+
   describe("update", () => {
     const supportMatrix = getSupportMatrix(reports, bcd.browsers, overrides);
     let bcdCopy;
diff --git a/scripts/update-bcd.ts b/scripts/update-bcd.ts
index a406fa603..b15804f0c 100644
--- a/scripts/update-bcd.ts
+++ b/scripts/update-bcd.ts
@@ -684,6 +684,42 @@ const skipCurrentBeforeSupport = skip("currentBeforeSupport", ({
   }
 });
 
+export const hasSupportMatrixContradictions = (
+  versionMap: BrowserSupportMap,
+  simpleStatement?: SimpleSupportStatement,
+) => {
+  if (!simpleStatement || simpleStatement.version_added === null) {
+    return true;
+  }
+
+  const contradictions: string[] = [];
+  for (const [version, supportAssertion] of versionMap.entries()) {
+    if (supportAssertion === null) {
+      continue;
+    }
+
+    if (typeof simpleStatement.version_added === "boolean") {
+      if (simpleStatement.version_added !== supportAssertion) {
+        contradictions.push(version);
+      }
+    }
+
+    if (typeof simpleStatement.version_added === "string") {
+      const simpleAdded = simpleStatement.version_added.replace("≤", "");
+      if (compareVersions(version, simpleAdded, "<") && supportAssertion) {
+        contradictions.push(version);
+      }
+      if (
+        compareVersions(version, simpleAdded, ">=") &&
+        supportAssertion === false
+      ) {
+        contradictions.push(version);
+      }
+    }
+  }
+  return contradictions.length > 0;
+};
+
 const persistInferredRange = provideStatements(
   "inferredRange",
   ({
@@ -924,6 +960,19 @@ export const update = (
       }
     }),
     skipBrowserMismatch(options.browser),
+    provideAllStatements,
+    provideDefaultStatements,
+    skip("supportMatrixMatchesDefaultStatements", ({
+      shared: {versionMap},
+      defaultStatements: [simpleStatement],
+    }) => {
+      if (!hasSupportMatrixContradictions(versionMap, simpleStatement)) {
+        return reason(
+          ({path, browser}) =>
+            `$${path} skipped for ${browser} because support matrix matches current BCD support data`,
+        );
+      }
+    }),
     provide("inferredStatements", ({shared: {versionMap}}) =>
       inferSupportStatements(versionMap),
     ),
@@ -936,8 +985,6 @@ export const update = (
       }
     }),
     skipReleaseMismatch(options.release),
-    provideAllStatements,
-    provideDefaultStatements,
     skip("zeroDefaultStatements", ({
       inferredStatements: [inferredStatement],
       defaultStatements,
@@ -976,8 +1023,21 @@ export const update = (
     persistAddedOver,
     persistRemoved,
     clearNonExact(options.exactOnly),
-    skip("noStatement", ({statements}) => {
+    skip("noStatement", ({
+      statements,
+      defaultStatements: [simpleStatement],
+      shared: {versionMap},
+    }) => {
       if (!statements?.length) {
+        if (hasSupportMatrixContradictions(versionMap, simpleStatement)) {
+          return reason(
+            ({browser, path}) =>
+              `${path} skipped for ${browser} with unresolved differences between support matrix and BCD data. Possible intervention required.`,
+            {
+              quiet: false,
+            },
+          );
+        }
         return reason(
           ({browser, path}) =>
             `${path} skipped for ${browser}: no known reason identified. Possible intervention required.`,

From ace7e41def04a6539fd9cb378d0c13c5046f3a33 Mon Sep 17 00:00:00 2001
From: Chris Cuellar <58723+ChrisC@users.noreply.github.com>
Date: Wed, 29 Nov 2023 13:59:44 -0800
Subject: [PATCH 3/7] adds check for "preview" statement

---
 scripts/update-bcd.test.ts | 13 +++++++++++++
 scripts/update-bcd.ts      |  4 ++++
 2 files changed, 17 insertions(+)

diff --git a/scripts/update-bcd.test.ts b/scripts/update-bcd.test.ts
index f1c9b8f88..995161f5f 100644
--- a/scripts/update-bcd.test.ts
+++ b/scripts/update-bcd.test.ts
@@ -938,6 +938,19 @@ describe("BCD updater", () => {
         ),
         "detects possible support removal",
       );
+
+      assert.isTrue(
+        hasSupportMatrixContradictions(
+          new Map([
+            ["79", false],
+            ["80", true],
+            ["81", true],
+          ]),
+          {
+            version_added: "preview",
+          },
+        ),
+      );
     });
   });
 
diff --git a/scripts/update-bcd.ts b/scripts/update-bcd.ts
index b15804f0c..a00d155e8 100644
--- a/scripts/update-bcd.ts
+++ b/scripts/update-bcd.ts
@@ -692,6 +692,10 @@ export const hasSupportMatrixContradictions = (
     return true;
   }
 
+  if (simpleStatement.version_added === "preview") {
+    return true;
+  }
+
   const contradictions: string[] = [];
   for (const [version, supportAssertion] of versionMap.entries()) {
     if (supportAssertion === null) {

From 846fb2e6e59fb432191673577eb6d067504c1a08 Mon Sep 17 00:00:00 2001
From: Chris Cuellar <58723+ChrisC@users.noreply.github.com>
Date: Mon, 4 Dec 2023 15:08:19 -0800
Subject: [PATCH 4/7] catches specific version_added updates over generic
 support statements

---
 scripts/update-bcd.test.ts | 14 +++++++++++---
 scripts/update-bcd.ts      |  4 +++-
 unittest/bcd.test.ts       |  3 +++
 3 files changed, 17 insertions(+), 4 deletions(-)

diff --git a/scripts/update-bcd.test.ts b/scripts/update-bcd.test.ts
index 995161f5f..37043f834 100644
--- a/scripts/update-bcd.test.ts
+++ b/scripts/update-bcd.test.ts
@@ -286,6 +286,11 @@ const reports: Report[] = [
           exposure: "Window",
           result: false,
         },
+        {
+          name: "api.unspecifiedVersionAPI",
+          exposure: "Window",
+          result: true,
+        },
         {
           name: "css.properties.font-family",
           exposure: "Window",
@@ -865,12 +870,12 @@ describe("BCD updater", () => {
         }),
         "skips generic false statements",
       );
-      // TODO: verify this is the result that we want
-      assert.isFalse(
+
+      assert.isTrue(
         hasSupportMatrixContradictions(new Map([["80", true]]), {
           version_added: true,
         }),
-        "skips generic true statements",
+        "catches specific support updates over generic true statements",
       );
 
       assert.isTrue(
@@ -1083,6 +1088,9 @@ describe("BCD updater", () => {
           SuperNewInterface: {
             __compat: {support: {chrome: {version_added: "100"}}},
           },
+          unspecifiedVersionAPI: {
+            __compat: {support: {chrome: {version_added: "≤85"}}},
+          },
         },
         browsers: {
           chrome: {name: "Chrome", releases: {82: {}, 83: {}, 84: {}, 85: {}}},
diff --git a/scripts/update-bcd.ts b/scripts/update-bcd.ts
index a00d155e8..596a2a85d 100644
--- a/scripts/update-bcd.ts
+++ b/scripts/update-bcd.ts
@@ -703,7 +703,9 @@ export const hasSupportMatrixContradictions = (
     }
 
     if (typeof simpleStatement.version_added === "boolean") {
-      if (simpleStatement.version_added !== supportAssertion) {
+      if (!simpleStatement.version_added && !supportAssertion) {
+        continue;
+      } else {
         contradictions.push(version);
       }
     }
diff --git a/unittest/bcd.test.ts b/unittest/bcd.test.ts
index db453aa07..075f1dd18 100644
--- a/unittest/bcd.test.ts
+++ b/unittest/bcd.test.ts
@@ -116,6 +116,9 @@ export default {
     SuperNewInterface: {
       __compat: {support: {chrome: {version_added: "100"}}},
     },
+    unspecifiedVersionAPI: {
+      __compat: {support: {chrome: {version_added: true}}},
+    },
   },
   browsers: {
     chrome: {name: "Chrome", releases: {82: {}, 83: {}, 84: {}, 85: {}}},

From 09eb95aa75a7a3c4e9a33d5e9ffd7506da4e7b18 Mon Sep 17 00:00:00 2001
From: Chris Cuellar <58723+ChrisC@users.noreply.github.com>
Date: Mon, 4 Dec 2023 15:13:10 -0800
Subject: [PATCH 5/7] walks back edits to "normal" update unit test

---
 scripts/update-bcd.test.ts | 8 --------
 unittest/bcd.test.ts       | 3 ---
 2 files changed, 11 deletions(-)

diff --git a/scripts/update-bcd.test.ts b/scripts/update-bcd.test.ts
index 37043f834..89640d132 100644
--- a/scripts/update-bcd.test.ts
+++ b/scripts/update-bcd.test.ts
@@ -286,11 +286,6 @@ const reports: Report[] = [
           exposure: "Window",
           result: false,
         },
-        {
-          name: "api.unspecifiedVersionAPI",
-          exposure: "Window",
-          result: true,
-        },
         {
           name: "css.properties.font-family",
           exposure: "Window",
@@ -1088,9 +1083,6 @@ describe("BCD updater", () => {
           SuperNewInterface: {
             __compat: {support: {chrome: {version_added: "100"}}},
           },
-          unspecifiedVersionAPI: {
-            __compat: {support: {chrome: {version_added: "≤85"}}},
-          },
         },
         browsers: {
           chrome: {name: "Chrome", releases: {82: {}, 83: {}, 84: {}, 85: {}}},
diff --git a/unittest/bcd.test.ts b/unittest/bcd.test.ts
index 075f1dd18..db453aa07 100644
--- a/unittest/bcd.test.ts
+++ b/unittest/bcd.test.ts
@@ -116,9 +116,6 @@ export default {
     SuperNewInterface: {
       __compat: {support: {chrome: {version_added: "100"}}},
     },
-    unspecifiedVersionAPI: {
-      __compat: {support: {chrome: {version_added: true}}},
-    },
   },
   browsers: {
     chrome: {name: "Chrome", releases: {82: {}, 83: {}, 84: {}, 85: {}}},

From 388dc62e75d5f9ab04fdbeb8a974c941a303c47e Mon Sep 17 00:00:00 2001
From: Chris Cuellar <58723+ChrisC@users.noreply.github.com>
Date: Thu, 7 Dec 2023 11:18:37 -0800
Subject: [PATCH 6/7] stops using "contradictions" terminology

---
 scripts/update-bcd.test.ts | 30 ++++++++++++++----------------
 scripts/update-bcd.ts      |  6 +++---
 2 files changed, 17 insertions(+), 19 deletions(-)

diff --git a/scripts/update-bcd.test.ts b/scripts/update-bcd.test.ts
index 89640d132..4b9eeffff 100644
--- a/scripts/update-bcd.test.ts
+++ b/scripts/update-bcd.test.ts
@@ -19,7 +19,7 @@ import {
   findEntry,
   getSupportMap,
   getSupportMatrix,
-  hasSupportMatrixContradictions,
+  hasSupportUpdates,
   inferSupportStatements,
   splitRange,
   update,
@@ -822,28 +822,26 @@ describe("BCD updater", () => {
     });
   });
 
-  describe("hasSupportMatrixContradictions", () => {
+  describe("hasSupportUpdates", () => {
     it("detects contradictions with nonexistent support statements", () => {
       assert.isTrue(
-        hasSupportMatrixContradictions(new Map([["80", true]]), {
+        hasSupportUpdates(new Map([["80", true]]), {
           version_added: null,
         }),
       );
 
-      assert.isTrue(
-        hasSupportMatrixContradictions(new Map([["80", true]]), undefined),
-      );
+      assert.isTrue(hasSupportUpdates(new Map([["80", true]]), undefined));
     });
 
     it("skips null support claims", () => {
       assert.isFalse(
-        hasSupportMatrixContradictions(new Map([["80", null]]), {
+        hasSupportUpdates(new Map([["80", null]]), {
           version_added: "≤80",
         }),
       );
 
       assert.isFalse(
-        hasSupportMatrixContradictions(
+        hasSupportUpdates(
           new Map([
             ["79", false],
             ["80", true],
@@ -860,21 +858,21 @@ describe("BCD updater", () => {
 
     it("detects contradictions in statements with boolean values", () => {
       assert.isFalse(
-        hasSupportMatrixContradictions(new Map([["80", false]]), {
+        hasSupportUpdates(new Map([["80", false]]), {
           version_added: false,
         }),
         "skips generic false statements",
       );
 
       assert.isTrue(
-        hasSupportMatrixContradictions(new Map([["80", true]]), {
+        hasSupportUpdates(new Map([["80", true]]), {
           version_added: true,
         }),
         "catches specific support updates over generic true statements",
       );
 
       assert.isTrue(
-        hasSupportMatrixContradictions(
+        hasSupportUpdates(
           new Map([
             ["80", false],
             ["81", true],
@@ -886,7 +884,7 @@ describe("BCD updater", () => {
 
     it("detects contradictions in statements with string values", () => {
       assert.isTrue(
-        hasSupportMatrixContradictions(
+        hasSupportUpdates(
           new Map([
             ["79", false],
             ["80", false],
@@ -899,7 +897,7 @@ describe("BCD updater", () => {
       );
 
       assert.isFalse(
-        hasSupportMatrixContradictions(
+        hasSupportUpdates(
           new Map([
             ["79", false],
             ["80", false],
@@ -912,7 +910,7 @@ describe("BCD updater", () => {
       );
 
       assert.isFalse(
-        hasSupportMatrixContradictions(
+        hasSupportUpdates(
           new Map([
             ["79", false],
             ["80", true],
@@ -925,7 +923,7 @@ describe("BCD updater", () => {
       );
 
       assert.isTrue(
-        hasSupportMatrixContradictions(
+        hasSupportUpdates(
           new Map([
             ["79", false],
             ["80", true],
@@ -940,7 +938,7 @@ describe("BCD updater", () => {
       );
 
       assert.isTrue(
-        hasSupportMatrixContradictions(
+        hasSupportUpdates(
           new Map([
             ["79", false],
             ["80", true],
diff --git a/scripts/update-bcd.ts b/scripts/update-bcd.ts
index 596a2a85d..33e515b66 100644
--- a/scripts/update-bcd.ts
+++ b/scripts/update-bcd.ts
@@ -684,7 +684,7 @@ const skipCurrentBeforeSupport = skip("currentBeforeSupport", ({
   }
 });
 
-export const hasSupportMatrixContradictions = (
+export const hasSupportUpdates = (
   versionMap: BrowserSupportMap,
   simpleStatement?: SimpleSupportStatement,
 ) => {
@@ -972,7 +972,7 @@ export const update = (
       shared: {versionMap},
       defaultStatements: [simpleStatement],
     }) => {
-      if (!hasSupportMatrixContradictions(versionMap, simpleStatement)) {
+      if (!hasSupportUpdates(versionMap, simpleStatement)) {
         return reason(
           ({path, browser}) =>
             `$${path} skipped for ${browser} because support matrix matches current BCD support data`,
@@ -1035,7 +1035,7 @@ export const update = (
       shared: {versionMap},
     }) => {
       if (!statements?.length) {
-        if (hasSupportMatrixContradictions(versionMap, simpleStatement)) {
+        if (hasSupportUpdates(versionMap, simpleStatement)) {
           return reason(
             ({browser, path}) =>
               `${path} skipped for ${browser} with unresolved differences between support matrix and BCD data. Possible intervention required.`,

From 1a15d198a36f6f6df4cd8f1f3d928474937e78ef Mon Sep 17 00:00:00 2001
From: Chris Cuellar <58723+ChrisC@users.noreply.github.com>
Date: Thu, 7 Dec 2023 11:35:56 -0800
Subject: [PATCH 7/7] fixes logic for handling "preview" statements

---
 scripts/update-bcd.test.ts | 20 +++++++++++++++++---
 scripts/update-bcd.ts      | 34 +++++++++++++++++-----------------
 2 files changed, 34 insertions(+), 20 deletions(-)

diff --git a/scripts/update-bcd.test.ts b/scripts/update-bcd.test.ts
index 4b9eeffff..a52d57757 100644
--- a/scripts/update-bcd.test.ts
+++ b/scripts/update-bcd.test.ts
@@ -823,7 +823,7 @@ describe("BCD updater", () => {
   });
 
   describe("hasSupportUpdates", () => {
-    it("detects contradictions with nonexistent support statements", () => {
+    it("detects updates with nonexistent support statements", () => {
       assert.isTrue(
         hasSupportUpdates(new Map([["80", true]]), {
           version_added: null,
@@ -856,7 +856,7 @@ describe("BCD updater", () => {
       );
     });
 
-    it("detects contradictions in statements with boolean values", () => {
+    it("detects updates in statements with boolean values", () => {
       assert.isFalse(
         hasSupportUpdates(new Map([["80", false]]), {
           version_added: false,
@@ -882,7 +882,7 @@ describe("BCD updater", () => {
       );
     });
 
-    it("detects contradictions in statements with string values", () => {
+    it("detects updates in statements with string values", () => {
       assert.isTrue(
         hasSupportUpdates(
           new Map([
@@ -950,6 +950,20 @@ describe("BCD updater", () => {
         ),
       );
     });
+
+    it("detects updates for preview statements", () => {
+      assert.isTrue(
+        hasSupportUpdates(new Map([["81", true]]), {
+          version_added: "preview",
+        }),
+      );
+
+      assert.isFalse(
+        hasSupportUpdates(new Map([["81", false]]), {
+          version_added: "preview",
+        }),
+      );
+    });
   });
 
   describe("update", () => {
diff --git a/scripts/update-bcd.ts b/scripts/update-bcd.ts
index 33e515b66..5334551ef 100644
--- a/scripts/update-bcd.ts
+++ b/scripts/update-bcd.ts
@@ -692,38 +692,38 @@ export const hasSupportUpdates = (
     return true;
   }
 
-  if (simpleStatement.version_added === "preview") {
-    return true;
-  }
-
-  const contradictions: string[] = [];
-  for (const [version, supportAssertion] of versionMap.entries()) {
-    if (supportAssertion === null) {
+  const updates: string[] = [];
+  for (const [version, hasSupport] of versionMap.entries()) {
+    if (hasSupport === null) {
       continue;
     }
 
     if (typeof simpleStatement.version_added === "boolean") {
-      if (!simpleStatement.version_added && !supportAssertion) {
+      if (!simpleStatement.version_added && !hasSupport) {
         continue;
       } else {
-        contradictions.push(version);
+        updates.push(version);
       }
     }
 
     if (typeof simpleStatement.version_added === "string") {
+      if (simpleStatement.version_added === "preview") {
+        if (hasSupport) {
+          updates.push(version);
+        }
+        continue;
+      }
+
       const simpleAdded = simpleStatement.version_added.replace("≤", "");
-      if (compareVersions(version, simpleAdded, "<") && supportAssertion) {
-        contradictions.push(version);
+      if (compareVersions(version, simpleAdded, "<") && hasSupport) {
+        updates.push(version);
       }
-      if (
-        compareVersions(version, simpleAdded, ">=") &&
-        supportAssertion === false
-      ) {
-        contradictions.push(version);
+      if (compareVersions(version, simpleAdded, ">=") && !hasSupport) {
+        updates.push(version);
       }
     }
   }
-  return contradictions.length > 0;
+  return updates.length > 0;
 };
 
 const persistInferredRange = provideStatements(